taxonID	type	description	language	source
03DFE565EA74D463FF1332C3D1E7FBA7.taxon	description	Description of male. Maximum body length 4.1 mm. Head lobe: triangular, apically acute. Antenna 1: accessory flagellum 1 article. Antenna 2: slightly stouter than antenna 1 but hardly longer, filter setae somewhat shorter, never with plumose setae; flagellum with at least the last two articles bearing posteriorly curved spines, first article considerably longer than any of the following articles. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1, article 2 with 1 row of facial setae. Gnathopod 1: coxa rectangular; propodus defined by 3 spines (medial-lateral-medial), these mid-distant along the palm; dactyl not facially striated. Gnathopod 2: with a gill; coxa deeper posteriorly; basis, anterolateral and anteromedial margins clothed in long plumose setae; carpus less than 1 / 4 propodus length; propodus, palm with a broad, bifid or trifid hinge tooth, defined by two narrow, apically acute teeth, these reaching nearly to the depth of the hinge tooth, thus giving the palm a transverse appearance; dactyl shorter than the propodus, inner margin slightly sinuous, tip reaching beyond the posterior defining tooth; dactyl, cusps reduced to small buttons interspersed with a few short setae. Pereopod 3: coxa deepest at the centre; basis not slenderer in larger males, margins convex; merus overlapping the carpus, anterior margin bearing a series of single plumose setae; propodus not posteriorly spinose. Pereopods 5 – 7: at least one basis posterodistally produced, anterior margin with a few short setae and no spines; merus not posteriorly spinose; carpus bearing 2 spines at the posterodistal angle on pereopod 5 and sometimes also on pereopod 6; spines lacking on pereopod 7; propodus not markedly expanded anteriorly; dactyl without facial striations, posterior (outer) margin not cusped distally, anterior (inner) margin bearing a seta only at the unguis. Pleopods: rami long, length> depth of the pleon, each with 2 coupling hooks. Urosome: segment 1 bearing a pair of setae dorsally. Uropod 3: peduncle mid-ventrally setose, without mid-dorsal spines or mid-ventral setae, but with a crown of spines dorsomedially at the insertion of the rami, and a small cluster of setae distolaterally; outer ramus not setose mid-dorsally, tipped by a basally immersed, dorsally recurved spine, a single seta at the spine’s point of immersion and a dorsal cluster of minute cusps proximal to the spine, none of these cusps particularly larger than the other; inner ramus with a single apical spine. Telson: dorsolateral cusps accompanied by setae (1 long, single and 2 short, plumose) but without spines. Description of adult female. Body length at maturity 2.4 – 4.0 mm. Character states as in the male except as follows. Brood plates: broad, setae abundant, hook-tipped. Antenna 2: posterior filter setae long, not shorter in larger individuals. Gnathopod 1: basis not flanged, without plumose setae. Gnathopod 2: propodus much larger and different in shape from the propodus of gnathopod 1 but differing only in the following respects from the large male: size slightly smaller, hinge tooth bifid, distal palmar tooth more central, proximal tooth little more than an acute expansion, bearing a large, single medial defining spine; dactyl, inner margin straight, tip apposing the defining spine.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA74D463FF1332C3D1E7FBA7.taxon	synonymic_list	Type species. Podocerus ocius Bate, 1862 (monotypy).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA74D463FF1332C3D1E7FBA7.taxon	etymology	Etymology. The name refers to the abundant plumose setae on the anterior legs, particularly gnathopod 2, which makes this genus unmistakable among the Jassa - like genera, even at young stages.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA6DD477FF1333A8D4E0FC13.taxon	description	(Figs 8 – 16)	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA6DD477FF1333A8D4E0FC13.taxon	description	Description of male. Type: based on CMNZ 2015.149.86 (Fig. 8). (Character states for the two males in Figs 10 and 11 added in brackets and italics if the appendage is obscured in the type). Length 4.0 (3.6, 3.3) mm. Antenna 1: accessory flagellum 2 articles (right), 3 articles (left). Antenna 2: similar in length and width to antenna 1, with filter setae in the male as long as in the juvenile and female; flagellum 7 articles, the last as long as the second last, article 1 25 % of full length, articles 5 – 7 posterodistally spinose. Mouthparts obscured (Mandible: articles 2 and 3 with a dorsal fringe of setae; raker spines, 4 right, 2 left. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1, article 2 with 1 row of facial setae distally). Gnathopod 1: coxae to propodus obscured (coxa rectangular, coxal margins, anterior 70 % of dorsal length, ventral margin gradually rounded; basis, anterior margin without a fringe of setae laterally, with only a few setae at the anterodistal junction with the ischium, with 1 long seta on the posterior margin; carpus, length 90 % of propodus length, posterior lobe 60 % of anterior margin length, anterodistal setal cluster short, 5 % of the anterior margin length; propodus, palm convex, defined by 1 spine); dactyl cusped distally, without facial striations. Gnathopod 2: (with a gill); coxae to antero-proximal part of propodus obscured (coxa not deeper posteriorly, coxal margins, anterior 100 % and posterior 100 % of ventral length, ventral margin gradually rounded; basis, anterolateral flange without a row of long, simple filter setae; carpus, anterior margin 50 % the length of the propodus anterior margin, posterior lobe with a cluster of short distal setae; propodus, anterior margin with only a few distal clusters of short setae (setae about 20 % of basis width )); propodus without hinge teeth, palm sparsely setose throughout, without a palmar defining spine, thumb conical in shape, 20 % the length of the propodus and carpus combined; dactyl shorter than propodus, not expanded near the hinge, tip apposing the thumb tip, inner margin cusped. Pereopod 3: coxa and basis obscured (coxa deepest centrally; basis wider than the gnathopod 1 basis, anterior margin shallowly convex); merus, anterior margin with one seta midway and cluster of setae distally, article width 70 % of length; carpus barely 20 % overlapped by merus; propodus width 47 % of length, not posteriorly spinose. Pereopods 5 – 7: proximally obscured (robust, basis, merus, carpus and propodus all bearing spines singly or in clusters; at least one basis posterodistally produced); propodus not strongly expanded anteriorly; dactyl not facially serrated, posterior (outer) margin not cusped distally, anterior (inner) margin setose only at the junction of the unguis. Pleopods: each with 2 coupling hooks (rami short, ≤ depth of the pleon). Urosome: segment 1 with pair of dorsally erect setae. Uropod 1: obscured (posteroventral spinous process underlying 83 % of the inner ramus, inner and outer rami with 2 mid-dorsal spines, outer ramus with 3 mid-dorsal spines, inner ramus with 1, in addition to the distal spine group). Uropod 2: obscured (peduncle, posteroventral spinous process underlying 25 % of the inner ramus). Uropod 3: partially obscured (peduncle not mid-ventrally setose, without mid-dorsal spines, without spines at the insertion of the rami, but with a cluster of setae distolaterally); outer ramus with 2 erect setae mid-dorsally (and tipped by 2 small, straight spines distolaterally and adjacent small cusp; inner ramus not mid-dorsally spinose or setose, with a single apical spine). Telson: partially obscured, with a pair of strong cusps dorsolaterally (and a single cusp at each dorsal apex, accompanied by a strong, erect seta and pair of small plumose setae). Condition. Whole body slide mounted; missing one pereopod 7. Description of adult female. Type: based on CMNZ 2015.149.85 (Fig. 9). Descriptions of characters not visible in the type are in brackets and italics and based on the adult female in Fig. 10. Length 3.8 (4.0) mm. Character states as in the male except as follows. Brood plates: obscured (relatively slender, setae well separated, abundant, hook-tipped). Antennae 1 and 2: similar in length, article 5 without plumose setae, simple filter setae as long as those of the male. Gnathopod 2: propodus without a hinge tooth, palm 40 % of the posterior margin, setae not so dense as to obscure the palm’s shape, defined by 3 medial spines. Condition. Whole body slide mounted. Without right antenna 2 and pereopods 5 – 7, left pereopods 5 and 7. Variation. Maximum body length: male 4.5 mm, female 4.5 mm. There is some variation in the number of accessory flagellum articles on antenna 1. There can be 2 or 3 articles and this can also vary between right and left sides of an animal (Fig. 13). The females and small males can have 3 palmar defining spines on the propodus of gnathopod 2 rather than 2. The number of erect setae on the outer ramus of uropod 3 varies from 1 to 5.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA6DD477FF1333A8D4E0FC13.taxon	materials_examined	Type material examined. Type, conical thumbed ♂, CMNZ 2015.149. 86, Lyttelton Harbour, New Zealand, date unknown, Charles Chilton, coll. Type, adult ♀♀, CMNZ 2015.149. 85 and 84, Lyttelton Harbour, New Zealand, date unknown, Charles Chilton, coll. Other material examined. New Zealand: Lyttelton Harbour, date unknown but possibly 1883 or earlier, C. Chilton, coll., 3 conical thumbed ♂♂, 2 cubic thumbed ♂♂, 18 adult ♀♀, 5 juveniles (CMNZ 2015.149.575 ... 604); Lyttelton, 28 Mar. 1928, 1 conical thumbed ♂, 5 adult ♀♀ (SNM); Brighton, Otago, New Zealand, Jan. 1890, C. Chilton, coll., 1 cubic thumbed ♂ (CMNZ 2015.149.2161); Stewart I., date unknown, H. B. Kirk, coll., 1 adult ♀ (CMNZ 2015.149.2116); Huaroa Point, Whangaparaoa Peninsula, Auckland Province, New Zealand (36.595 ° S, 174.836 ° E), 16 Feb. 1968, J. L. Barnard, coll., NIWA station E 979, JLB NZ- 14, low water level, on heavy stand of algae, including Cystophora torulosa and bases of dying Codium sp., 1 cubic thumbed ♂ (NIWA 7825), 1 adult ♀ (NIWA 7835), 1 cubic thumbed ♂ (NIWA 7839); St. Kilda Rocks, Kaikoura (42.42 ° S, 173.7 ° E), 8 Nov. 1973, G. D. Fenwick, coll., 3 – 4 m depth on Caulerpa brownii and green algae, 8 cubic thumbed ♂♂ (AM P. 25948) and ~ 50 specimens (MNZTPT CR. 007823); Fraser Rocks, Tapeka, Bay of Islands, Northland, 15 Nov. 1995, 0 – 1 m, collector unknown, 31 conical thumbed ♂♂, 43 adult ♀♀, 23 juveniles (AuM MA 134534). Tristan da Cunha: type series for Jassa barnardi Stephensen, 1949: Norwegian Scientific Expedition, E. Sivertsen, coll., Nightingale station 113, 8 Feb. 1938, 19 conical thumbed ♂♂, 37 adult ♀♀, 56 juveniles (SNM), Nightingale station 114, 8 Feb. 1938, 0 m, 6 conical thumbed ♂♂, 21 adult ♀♀, 7 juveniles (UiO F 3934) and 1 conical thumbed ♂, 1 adult ♀ (CMNC 1994 – 0444), Inaccessible station 154, 25 Feb. 1938, 40 m, 1 conical thumbed ♂, 1 adult ♀, 10 juveniles (UiO F 3898), Inaccessible station 156, 29 Feb. 1938, 5 – 8 m, 3 adult ♀♀ (UiO F 3897), station unknown, 30 Dec. 1939, 1 juvenile (SNM). Chile: Caleta Bruna, date unknown, collector unknown., 1 conical thumbed ♂, 1 adult ♀, 1 juvenile (MNHN Am. 2649); Valparaiso, collector and date unknown, 1 conical thumbed ♂, 8 adult ♀♀, 2 juveniles (NRM 3786). South Africa: False Bay, date unknown, C. Griffiths, coll., station FAL 604 G, 1 cubic thumbed ♂, 1 juvenile ♂ (UCT).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA6DD477FF1333A8D4E0FC13.taxon	discussion	Remarks. Ventojassa frequens does not exhibit sexual dimorphism in the antenna 2 but does in the gnathopod 2 and enlargement of pereopods 5 and 6 relative to 7. The pereopod enlargement is particularly pronounced in large females though large males show this enlargement to a lesser extent. Chilton recognized two male morphs based on the male’s thumb shape and the expansion of the pereopods 5 and 6 (especially pereopod 6): conical thumb with “ stout ” pereopods 5 and 6 in his then named Podocerus frequens Chilton, 1883 and cubic thumb with “ much expanded ” pereopods 5 and 6 in his then named Podocerus latipes Chilton, 1884. However, Chilton (1884) had reservations about the two forms being different species, stating that Podocerus latipes “ ... may prove to be only a variety of P. frequens. ” Chilton (1921) added some collecting information for these specimens, stating that they were fairly common in Lyttelton Harbour at the roots of Macrocystis and other seaweeds above low-water level. Chilton (1921) also pointed out that Stebbing (1906) had synonymized the two species as Jassa frequens (Chilton, 1883), regarding the cubic thumbed morph illustrated by Chilton (1884) to be the male and seemingly ignoring the conical thumbed male illustrated earlier by Chilton (1883). Chilton’s type material listed in Shaw & Poore (2016) were kindly lent by the Canterbury Museum along with material from other locations listed above. The single male specimen that Chilton (1883) illustrated in his type description and Plate III, Fig. 2 was of a very small conical thumb (his Fig. 2 b) and this drawing does not correspond with the long conical thumb borne by the male slide mounted and designated type CMNZ 2015.149.86 (Fig. 8). Chilton (1883) did note in his new species description that “ The process on the propodos of second gnathopoda of male varies in size in different specimens, and is often longer and more distinct than shown in fig. 2 b. ” The other two type slides CMNZ 2015.149.84 and 85 are whole body mounts of adult females, but neither corresponds with Chilton’s (1883) Fig. 2, either. Chilton’s label on CMNZ 2015.149.84 states that the specimen is a male but it is actually an adult female with setose brood plates. Chilton (1921) also illustrated the cubic thumbed type of male gnathopod 2 in Fig. 4 A, p. 228 and this drawing matches the slide mounted male gnathopod 2 on Chilton’s slide CMNZ 2015.149.2161 from Brighton, Otago, New Zealand, collected Jan. 1890. Chilton’s (1921) Figs 4 B, C correspond to dissected appendages of a female from Stewart Island, collected by H. B. Kirk (CMNZ 2015. 149.2116). Chilton’s (1921) Fig. 4 D appears to be a pereopod 5 (not 6 as stated in the figure caption) but does not exactly match the pereopods on either of these slide mounts, showing fewer spines on the anterior margin of the basis. Jassa barnardi Stephensen, 1949 from Tierra del Fuego (type shown in Figs 10 and 11) is clearly the same as Chilton’s conical thumbed male (type male shown in Fig. 8). It has the same slender antennae, slender propodus of gnathopod 1, conical thumb on the propodus of gnathopod 2, minimal overlap of the merus over the carpus on pereopods 3 and 4 and wide merus and carpus on pereopods 5 – 7 with strong spination on the posterior margins. The same features of the urosome, not visible on Chilton’s slide mount of the type is evident in his un-mounted specimens preserved in alcohol (CMNZ 2015.149.575 ... 604). This forces its synonymy under Ventojassa frequens. Additional illustrations of specimens from more recent collections are given here for comparison (Figs 12 – 15). Fig. 16 shows a graph of thumb length relative to body length in the conical thumbed and cubic thumbed males. The majority of specimens were taken from recent collections in New Zealand but they correspond well with specimens from Chilton’s collection. The contrast between the two morphs is shown in the much longer thumb in the conical thumbed males compared to the cubic thumbed males of the same body length. Within the longer conical thumbed group, there is no marked transition in thumb length, suggesting that thumb production occurs gradually over several molts rather than at the terminal molt as in Jassa (Conlan, 1989). For the cubic thumbed group, the largest specimen showed a longer thumb than the others, but more specimens are needed to determine variation. Chilton’s two morphs may indeed be separate species, but this requires DNA analysis as no non-sexually dimorphic characters could be found that separated the two morphs. While large males could be distinguished based on thumb morphology (conical vs cubic), and large females found with the cubic thumbed males had grossly enlarged pereopods 5 and 6 while large females found with conical thumbed males had less enlarged pereopods 5 and 6, smaller females and thumbless males could not be assigned to the two morphs. In addition, the two morphs appeared to co-occur, as evidenced by Chilton’s collection from Lyttelton, New Zealand (CMNZ 2015.149.575 ... 604), which contained 3 conical thumbed males and 2 cubic thumbed males, as well as adult females with a range of moderately to grossly enlarged pereopods 5 and 6. There was also a juvenile Jassa gruneri Conlan, 1990 mixed in. One of the two cubic thumbed males in this collection is the one likely used by Chilton (1884) to illustrate the second gnathopod of the male Podocerus latipes in his type description, as this appendage had been torn off from the right side and the left gnathopod 2 corresponded with his Plate XIX, Fig. 2 b. K. H. Barnard (1932) illustrated a conical thumbed male gnathopod 2 of a specimen named “ Jassa pusilla ” captured at Tristan da Cunha 30 Jan. 1926 at 40 – 46 m on a R. S. S. Discovery expedition. Stephensen (1949) noted that this was the same as his new species Jassa barnardi (herein transferred to V. frequens as stated above). He listed additional specimens to those examined for this study collected at Tristan da Cunha, Nightingale and Inaccessible Islands at 0 – 40 m depth. The specimens listed by Schellenberg (1931) from Valparaiso and Iquique, Chile (just south of Caleta Bruna) were possibly those examined for this paper and listed above. Schellenberg (1953) illustrated a cubic thumbed male gnathopod 2 and the urosome of a female from L ̹ deritz bay, Namibia (not seen). In his New Zealand study, J. L. Barnard (1972) collected V. frequens from washes of mixed species of low intertidal algae at stations in Dunedin, Lyttelton, Kaikoura, Wellington, and Leigh in addition to the cubic thumbed morph he illustrated from Huaroa Point and examined for this paper. These have not been seen but are likely to be the same cubic thumbed morph as otherwise, J. L. Barnard would likely have remarked on the difference. Additional unexamined collections of V. frequens from the Bay of Islands, Waitemata Harbour, Leigh, Hahei, and the Chatham Islands, New Zealand (0 – 12 m depth) are held at the Auckland Museum (AuM). Griffiths (1975) recorded two collections of V. frequens from False Bay, South Africa. No station number was given, so it could not be determined whether either of these corresponded to a single False Bay collection (station FAL 604 G) that was lent by Griffiths for this study. This collection held a cubic thumbed morph. There are eight species of Ventojassa currently known (ordered by date of description and collection location): V. ventosa (J. L. Barnard, 1962) from California, V. crenulata Ledoyer, 1979 from Madagascar, V. dentipalma Kim & Kim, 1991 from Korea, V. helenae Vader & Myers, 1996 and V. zebra Vader & Myers, 1996 from Australia, V. beagle Alonso, 2012 from Argentina and V. palauensis Myers, 2013 from Palau. Of these, V. frequens may be closest to the Australian V. helenae and V. zebra which share the broad merus and carpus on pereopod 5. However, V. frequens has a narrower palm of gnathopod 1, a different ornamentation of the palm of gnathopod 2, pereopod 5 is without stridulating ridges, and pereopod 6 is more spinose and (especially in larger males and females) markedly stouter than pereopod 7. Common to other species of Ventojassa, V. frequens has a strongly produced interramal spinous process underlying the rami of uropods 1 and 2 but this is almost as long as the rami, where in other species it is typically shorter.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA61D474FF13336AD4C5FAD7.taxon	discussion	Genus Hemijassa Walker, 1907. Hemijassa Walker, 1907, 38.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA61D474FF13336AD4C5FAD7.taxon	description	Description of male. Maximum body length 22 mm. Head lobe: squared, angles acute. Antenna 1: accessory flagellum 2 articles, the second minute, only the second article setose. Antenna 2: stouter and longer than antenna 1, the filter setae progressively shorter; flagellum with all but the first article bearing spines on the posterior margin, first article considerably longer than any of the following articles. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1; article 2 with many scattered rows of facial setae distally. Gnathopod 1: coxa rectangular; propodus, palm defined by 4 spines located proximally of centre; dactyl not facially striated. Gnathopod 2: with a gill; coxa not deeper posteriorly; basis, filter setae simple or finely barbed and located on the anterolateral flange only; carpus less than 1 / 4 propodus length; propodus with a pronunced conical, multiply incised tooth below the dactyl hinge, and a larger acute thumb with 3 minute palmar defining spines at its tip, thumb setose on both inner and outer margins; dactyl shorter than the propodus, inner margin not expanded, tip resting on the tip of the thumb or between the thumb’s anterior margin and the palm; dactyl cusps reduced to small buttons interspersed with a few short setae. Pereopods 3 and 4: coxae rectangular; basis, margins more parallel than convex; merus slightly overlapping the carpus, anterior margin bearing discrete clusters of setae; propodus not posteriorly spinose. Pereopods 5 – 7: at least one basis posterodistally produced, anterior margin with a few short setae; merus and carpus, posterior margin not spinose; dactyl without facial serrations, posterior (outer) margin not cusped distally, anterior (inner) margin bearing a row of setae along its length. Pleopods: rami long, length> depth of the pleon, each with> 2 coupling hooks. Urosome: segment 1 bearing a pair of erect setae dorsally. Uropod 3: peduncle mid-ventrally setose and spinose, without spines mid-dorsally, with a ventral row of short setae, with a crown of spines dorsomedially at the insertion of the rami and a cluster of setae distolaterally; outer ramus not setose mid-dorsally, tipped by a basally immersed, dorsally recurved spine and minute serrations dorsally, but without cusps; inner ramus with a single apical spine. Telson: each corner with a pair of dorsolateral cusps and accompanying setae (1 long, simple and 2 short, plumose) but without spines. Description of adult female. Maximum body length 20 mm. Character states as in the male except as follows. Brood plates: broad, setae abundant, hook-tipped. Antenna 2: peduncle, posterior filter setae long, not shorter in larger individuals. Gnathopod 2: propodus and dactyl much larger and different in shape from that of the male. Pereopods 3 and 4: basis slender as in the male.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA61D474FF13336AD4C5FAD7.taxon	type_taxon	Type species. Jassa goniamera Walker, 1903 (monotypy).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA61D474FF13336AD4C5FAD7.taxon	discussion	Remarks. Walker (1903) first suggested the genus name but decided to place his new species (goniamera) under Jassa. Walker (1907) transferred J. goniamera to Hemijassa after it was pointed out by other taxonomists that it did not fit in Jassa, Ischyrocerus or Bruzeliella Norman, 1905 (the latter synonymized by Walker 1911 under Jassa) based on characteristics of the antennal accessory flagellum and uropod 3. However, taxonomists appear to have disregarded the transfer of J. goniamera to Hemijassa and continued to assign H. goniamera to Jassa, as J. goniamera, J. falcata (Montagu, 1808), J. ingens Pfeffer, 1888 or J. wandeli (Bellan-Santini 1972; Thurston 1974 b; Lowry & Bullock 1976). Sexton & Reid (1951) erroneously submerged the genus and species under Jassa falcata. Hemijassa is formally re-erected here as H. goniamera is clearly not a species of Jassa, as noted by Conlan (1989, 1990). In Hemijassa, gnathopod 2 morphology is unlike that of Jassa. The “ thumb ” is at, rather than distal to, the palmar defining spines, and occurs in both sexes. The “ thumb ” in Hemijassa could be considered homologous to the ledge that develops at the defining spines in Jassa morinoi Conlan, 1990 and J. ingens, and thus bears no homology to the Jassa thumb at all. There is no evidence of a transformational increase in thumb length relative to body length as occurs in Jassa. The lack of sexual difference in the shape of the bases of pereopods 3 and 4 is also suggestive of a different sexual life style. In Jassa, the pereopod 3 and 4 bases are broadly convex in non-thumbed males and females but slender in thumbed males. This difference corresponds with abandonment of a tubicolous lifestyle in Jassa once the males develop a thumb and a roving behaviour in search of receptive females to mate with (Borowsky, 1985).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA62D44EFF13325CD4DBFB1F.taxon	description	(Figs 17 – 21)	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA62D44EFF13325CD4DBFB1F.taxon	description	Description of male. Lectotype (here designated): Length 18.3 mm. Antenna 2: overlapped by antenna 1 to midway along article 5; article 5, posterior marginal setae very short and simple, minute compared with those of the female; flagellum 8 articles, the last 1 / 2 the size of the second last, article 1 46 % of full length. Mandible: palp articles 2 and 3 with a dorsal fringe of setae; raker spines 6 right, 8 left. Gnathopod 1: coxal margins, anterior 72 % of dorsal length, ventral margin straight; basis, anterior margin with a fringe of long setae laterally, posterior margin with many setae also, which are just as long and wide ranging as on the anterior margin, but more scattered; carpus, length 64 % of propodus length, posterior lobe 47 % of anterior margin length, anterodistal setal cluster short, 25 % of the anterior margin length; propodus, palm convex; dactyl cusped along the full length, without facial striations. Gnathopod 2: coxal margins, anterior 87 % and posterior 100 % of ventral length, ventral margin straight; basis, anterolateral flange with a row of long, simple filter setae (setae about 1 / 2 article width); carpus, posterior lobe with a cluster of distal setae; propodus, anterior margin with a series of clusters of short setae (setae about 1 / 2 basis width). Pereopod 3: basis narrower than the gnathopod 1 basis, anterior margin shallowly concave; merus, anterior margin with a row of setae along its length, article width 45 % of length; carpus barely 10 % overlapped by merus; propodus width 40 % of length. Pereopods 5 – 7: basis posterodistally produced, anterior margin with a few short setae; merus and carpus, posterior margin not spinose. Uropod 1: peduncle, posteroventral spinous process underlying 41 % of the inner ramus, inner and outer rami with 12 and 13 mid-dorsal spines respectively, not terminating in a fringe of cusps ventral to the apical spine group. Uropod 2: peduncle, posteroventral spinous process underlying 25 % of the inner ramus. Uropod 3: inner ramus not mid-dorsally spinose. Condition. Left antenna 1, tip of flagellum missing, without left pereopod 7. Right appendages, telson and mouthparts slide mounted. Description of adult female. Paralectotype: Length 19.9 mm. As in the genus description. Condition. With all appendages. Right appendages, telson and mouthparts slide mounted. Variation. Maximum body length: male 22 mm, female 20 mm. Hemijassa goniamera exhibits sexual dimorphism in the antenna 2 and gnathopod 2. The antenna 2 development appears to be much like that in species of Jassa, with antennae long with short filter setae in large males compared to females and small males (Figs 17, 18 and 20). The palm of gnathopod 2 is sinuous in small males, but with a ledge or tooth in large males (Fig. 20). In females the palm remains sinuous at all sizes (Fig. 18).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA62D44EFF13325CD4DBFB1F.taxon	materials_examined	Type material examined. Lectotype, ♂, NHM 1987: 515, Cape Adare, McMurdo Sound, Ross Sea, Antarctica (71 ° 17 ʹS, 170 ° 14 ʹE), “ Southern Cross ” Expedition, 5 November 1902. Paralectotypes, 5 ♂♂, 9 adult ♀♀, 6 small (juvenile?) males and 10 juvenile females, NHM 1902.11.5: 6 – 10 (part), same location. Other material examined. South Sandwich Islands: Visokoi I., 13 Nov. 1908, 60 – 100 m, C. A. Larsen, coll., 1 ♀ (UiO F 2968). South Shetland Islands, Antarctica: off Cape Bowles, Clarence I., 23 Feb. 1927, ‘ Discovery’ station 170, 342 m, 5 ♂♂, 8 ♀♀ (NHM 1936: 11.2: 2411 – 2426 (part )); Bransfield Strait, 2 Mar. 1927, ‘ Discovery’ station 175, 200 m, 1 ♂ (NHM 1936.11.2: 2411 – 2428 (part). Graham Region, Antarctica: Seymour I. (64 ° 20 ʹS, 56 ° 38 ʹW), 16 Jan. 1902, 150 m, Svenska Sydpolarexp. 1901 – 1903, No. 5, 3 juveniles (SNM) and 10 juveniles (NRM 3679); SW of Snow Hill I., (64 ° 36 ʹS, 57 ° 42 ʹW), 20 Jan. 1902, 125 m, Svenska Sydpolarexp. 1901 – 1903, No. 6, 1 ♂, 1 ♀, 1 juvenile (NRM 3680). Ross Sea, Antarctica: Coulman I., 13 Dec. 1902, 183 m, 1 ♂, 1 ♀ (NHM 1907.6.6: 410 – 415); Flagon Pt., Winter Quarters Bay, McMurdo Sound, 23 Jan. 1903, ‘ Discovery’ Expedition, 1 ♂, 1 ♀, 1 juvenile (NHM 1907.6.6.414 – 415); Flagon Pt., Winter Quarters Bay, McMurdo Sound, 17 Jan. 1903, ‘ Discovery’ Expedition, 3 ♀♀ (NHM 1907.6.6: 410 – 415). Weddell Sea, Antarctica: Cap Norvegia, (71 ° 2 ʹS, 12 ° W), 17 Feb. 1930, Norvegia Expedition, Riiser-Larsen, 1 ♀ (UiO); off Kapp Norvegia (70.0145 ° S, 10.00806 ° W), 30 Jan. 1998, Agassiz trawl beginning at 246 m, C. de-Broyer and Y. Scailteur, coll., Polarstern EASIZ II Expedition (Ant XV / 3), 1 ♂ (RBINS IG 28520); off Kapp Norvegia (70.01461 ° S, 10.00794 ° W), 31 Jan. 1998, Agassiz trawl beginning at 248 m, C. deBroyer and Y. Scailteur, coll., Polarstern EASIZ II Expedition (Ant XV / 3), 2 ♂♂ (RBINS IG 28252). Commonwealth Bay, Antarctica: 21 Dec. 1913, 10 – 120 m, Australasian Antarctic Expedition, 1 ♂ (AM P. 18415). Terre Adélie, Antarctica: Archipel de Pointe Géologie, 2 Jan. 1965, 110 – 130 m, fond à bryozoaires, hydraires, spongiaires et alcyonaires, P. M. Arnaud, coll., station TA-D 102 (D. Bellan-Santini loan).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA62D44EFF13325CD4DBFB1F.taxon	discussion	Remarks. Schellenberg (1926) may have recorded H. goniamera at Gauss-Station (Kaiser Wilhelm II Land) during the Deutsche S ̹ dpolar-Expedition 1901 – 1903, collected on August 12, 1902 and named it Jassa falcata. Other specimens listed as “ J. falcata ” may have been P. wandeli, judging by their size and collection location. One collection of “ J. falcata ” from Terre Adélie, Antarctica and listed in Bellan-Santini (1972) was examined and found to be H. goniamera. It is likely that the other three collections listed therein (not seen) are also H. goniamera, judging by the size of the specimens (7 – 17 mm) and depth of collection (15 – 140 m). Hemijassa goniamera is only known subtidally and can be found clinging to bryozoans and hydroids (Dauby et al. 2001). Trace metal levels are relatively low in H. goniamera and well within the range of other Antarctic amphipods (Keil et al. 2008).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA58D44CFF133270D0F8FE08.taxon	description	Description of male. Maximum body length 10.8 mm. Head lobe: squared, dorsal angle more acute, lower angle lobe more rounded. Antenna 1: accessory flagellum 2 articles, the second minute, setose only distally. Antenna 2: stouter and longer than antenna 1, setation variable, filter setae shorter and sparser in larger individuals, flagellum spination variable, first article considerably longer than following articles. Maxilla 1: inner plate bearing a few short, fine setae; palp without setae at the base of article 1, article 2 with 1 row of facial setae. Gnathopod 1: coxa rectangular; carpus, anterior margin length <propodus length; propodus, palm defined by 1 – 2 medial defining spines, this central or slightly proximal of centre; dactyl facially striated. Gnathopod 2: without a gill; coxa not deeper posteriorly; basis without filter setae; carpus a quarter of propodus length or less, lobe apically setose; propodus without anteroproximal setae, hinge tooth rectangular cuboid or conical, shallowly or deeply bifid, or multiply incised, palm concave to the single medial defining spine, there produced or not into a short “ hook ” or long thumb; dactyl shorter than the propodus, variably expanded at the hinge tooth, tip apposing the defining spine, or if thumb present, its posterior margin, cusps reduced and interspersed with short setae. Pereopod 3: coxa deepest centrally or slightly posterior of centre; basis a little slenderer in larger individuals; merus, anterior margin bearing well-spaced single or clustered setae; carpus, overlap by merus variable; propodus not posteriorly spinose. Pereopods 5 – 7: basis variably posterodistally produced or not produced, anterior margin spinose or setose; merus not posterodistally spinose; carpus with a cluster of spines posterodistally at least on pereopod 5; propodus not strongly expanded anteriorly; dactyl not facially serrated, posterior (outer) margin not cusped distally, anterior (inner) margin, setation variable. Pleopods: rami very short, length ± depth of the pleon, each with 2 coupling hooks. Urosome: segment 1 with dorsal pair of erect setae. Uropod 3: peduncle mid-ventrally setose, without mid-dorsal spines, but with a crown of spines dorsomedially at the insertion of the rami and a cluster of setae distolaterally; outer ramus not setose mid-dorsally, tipped by a basally immersed, dorsally recurved spine and associated seta and serrations, cusps variable, but never as on Jassa; inner ramus with or without a spine or spines mid-dorsally in addition to the single apical spine. Telson: each dorsolateral corner with a pair of cusps accompanied by setae (2 long, simple, and 2 short, plumose) but not spines. Description of adult female. Maximum body length 9.8 mm. Character states as in the male except as follows. Brood plates: broad, setae well separated, abundant, at least some hook-tipped. Antenna 2: peduncle, posterior filter setae long, not shorter in larger individuals. Gnathopod 2: propodus much larger and different in shape from propodus of gnathopod 1, palm concave, defined by a single medial spine and without a thumb; dactyl tip apposing the defining angle and spine, dactyl cusps strong. Pereopod 3: basis somewhat broader than in the male. Variation. Antenna 2 peduncular setal change appears to be similar to that of Jassa, with the male’s setae shorter in larger specimens and the female’s remaining long. Male gnathopod 2 thumbing is not homologous, however, because the thumb develops at the palmar defining spine rather than distal to it. Consequently the thumb’s setation pattern is quite different.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA58D44CFF133270D0F8FE08.taxon	type_taxon	Type species. Jassa wandeli Chevreux, 1906.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA58D44CFF133270D0F8FE08.taxon	discussion	Remarks. Distinguishing features from Jassa are a single spine defining the palm of gnathopod 2, and hence different thumb setation, closure of the second gnathopod’s dactyl at, rather than distal to, the defining spine, lack of a gnathopod 2 gill, reduced pleopods and lack of a double cusp on the uropod 3 outer ramus. The males of P. wandeli and P. multidentata produce a long thumb if sufficiently larger than the adult female and thus would superficially appear to be a Jassa. Thumb development appears from specimens to be a progressive transformation, not at a terminal molt, however (although this has not been tested experimentally as it has for Jassa). Males of P. orientalis probably also produce a thumb as this species closely resembles P. multidentata. Pleojassa moorei and P. lowryi are not known to produce thumbs in the males and sufficient specimens were available to find males of similar or larger size than adult females to indicate that the males were adult as well. However, the five species resemble each other in characters that are conservative within Jassa, such as the tendency toward setal reduction in the antenna 2 of the male compared to the female, and in similar morphologies of the mouthparts, gnathopod 1, female gnathopod 2, female brood plates and third uropod hooking.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA5AD441FF13352DD6D5FD73.taxon	description	(Figs 22 – 24) Description of male. Holotype: Length 4.0 mm. Antenna 1: missing. (Male, 3.4 mm, not type, CMN IZ 1989 - 013, antenna 2 overlapped by antenna 1 to midway along article 5). Antenna 2: article 5 bearing a few simple setae only, these about as long as those of the female; flagellum 3 articles, article 1 75 % of full flagellum length. Mandible: palp articles 2 and 3 without a dorsal fringe of setae; raker spines 3 right, 4 left. Gnathopod 1: coxal margins, anterior 92 % of dorsal length; ventral margin straight; basis, anterior and posterior margins each with a single seta distally; carpus, length 80 % of propodus length, posterior lobe 47 % of anterior margin length, without an anterodistal setal cluster; propodus, palm convex, one defining spine slightly proximal of centre. Gnathopod 2: coxal margins, anterior 65 % and posterior 61 % of ventral length, ventral margin sinuous; carpus 1 / 4 the length of propodus; propodus with 2 hinge teeth, palm sparsely setose throughout, defined by a single spine, this not associated with a discrete thumb-like extension from the palm. Pereopod 3: basis slender, anterior margin shallowly convex; merus, anterior margin setose only distally, article width two thirds of length; carpus a third overlapped by the merus; propodus width 44 % of length. Pereopods 5 – 7: slender, setae and spines sparse, basis not posterodistally produced, anterior margin with a few short setae; merus, posterior margin not spinose. Uropod 1: peduncle, posteroventral spinous process underlying 88 % of the inner ramus, inner and outer rami with 1 and 3 mid-dorsal spines respectively. Uropod 2: peduncle, posteroventral spinous process underlying 21 % of the inner ramus. Uropod 3: inner ramus not mid-dorsally spinose. Condition. Without antennae 1, right antenna 2 or left pereopod 3. Remaining right appendages, telson and mouthparts slide mounted. Remaining left appendages with the carcass. Description of adult female. Allotype: Length 4.25 mm. Character states as in the male except as follows. Antenna 2: only slightly longer than antenna 1, article 5 without plumose setae, simple filter setae about twice the length of those of the comparably sized male. Gnathopod 2: propodus without a hinge tooth, palm 40 % of the posterior margin, setae not so dense as to obscure the palm’s shape. Condition. Without antennae 1 and right pereopod 6. Right antenna 2 and gnathopod 2 slide mounted. Other appendages with the carcass. Variation. Maximum body length: male 4.0 mm, female 4.5 mm. Examination of 8 males and 8 females from the type collection showed no variation in the antenna 1 accessory flagellum with consistently 3 articles. No thumb is produced on the propodus of gnathopod 2 to indicate the sexual state of males as in Jassa (Borowsky, 1985). However, there is some indication of adulthood in the larger antenna 2 and propodus of the gnathopod 2 as well as a longer palm and more pronounced hinge tooth in the male than in the female of similar body length (Figs 22 and 23).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA5AD441FF13352DD6D5FD73.taxon	materials_examined	Type material examined. Holotype, ♂, Billie Rocks, Signy Island, South Orkney Islands (60 ° 43 ʹS, 45 ° 38 ʹW), 4 March 1965, M. H. Thurston, coll., 3.1 – 3.4 m depth, diver collection of Lithothamnia, Desmarestia anceps, D. chordalis, Ascoseira mirabilis, Rhodophyceae, Porifera, and Polyzoa off solid rock inclined at 65 ° (NHM, registration no. 1987: 511, station no. 13 (244 )). Allotype, ♀, same location (NHM, registration no. 1987: 512). Paratypes, ~ 200 specimens, same location (NHM, registration no. 1969: 768 (pt. )). Other material examined. (excluded from type series): South Georgia: no. 10427, (54 ° 30 ʹ 58 ʺS, 36 ° 0 ʹ 45 ʺW), K. von den Steinen, coll., 16 January 1884, 1 juvenile (ZMH K- 28907). South Orkney Islands: 38 collections from Billie Rocks, Berntsen Point, Outer Islet and Paal Harbour, Signy Island, Dec. – July 1964 and Feb. – Mar. 1965, ~ 1350 specimens (NHM stations 9 – 12, 15 – 26, 30, 32 – 35, 40, 46 – 49, 54).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA5AD441FF13352DD6D5FD73.taxon	etymology	Etymology. In appreciation of Dr. Geoff Moore’s contributions to our knowledge of the systematics, ecology and behaviour of amphipods and of his assistance in locating specimens for this study.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA5AD441FF13352DD6D5FD73.taxon	discussion	Remarks. Table 4 summarizes obvious differences between P. moorei and P. lowryi. Thurston (1974 b) collected 2,912 specimens at 29 stations on Signy Island and named this species Jassa falcata form 3. The additional collections examined here were split collections from the same station.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA57D446FF1335F2D77EFCE3.taxon	description	(Figs 25 and 26) Description of male. Holotype: Length 5.3 mm. Without antenna 1. (Paratype, male, 3.8 mm, antenna 2 overlapped by antenna 1 to the end of article 5). Antenna 2: article 5 and flagellum, posterior margin bearing abundant plumose setae, simple filter setae interspersed, these sparser and shorter than in the female; flagellum 3 articles, article 1 86 % of full flagellum length. Mandible: palp articles 2 and 3 without a dorsal fringe of setae; raker spines 4 right, 6 left. Gnathopod 1: coxal margins, anterior 112 % of dorsal length; ventral margin straight; basis, antero-medial margin with a row of short, spine-like setae, antero-lateral and posterior margins setose only distally; carpus, length 60 % of propodus length, posterior lobe 42 % of anterior margin length, setal cluster short, 16 % of the anterior margin length; propodus, palm nearly straight, one defining spine slightly proximal of centre. Gnathopod 2: coxal margins, anterior 48 % and posterior 70 % of ventral length; ventral margin shallowly concave; carpus less than a quarter the length of the propodus; propodus, hinge tooth conical, shallowly bifid, palm densely plumose throughout, defined by a single minute spine at the end of a short hook-like protuberance. Pereopod 3: basis slender, anterior margin shallowly convex; merus, anterior margin setose centrally and distally, central setae less than 1 / 4 article width, article width 73 % of length; carpus three quarters to fully overlapped by the merus; propodus width 58 % of length. Pereopods 5 – 7: stout, basis of pereopod 6 and 7 posterodistally produced, anterior margin of each basis spinose; merus bearing spines along its posterior margin. Uropod 1: peduncle, posteroventral spinous process underlying 39 % of the inner ramus, inner and outer rami with 3 and 5 mid-dorsal spines respectively. Uropod 2: peduncle, posteroventral spinous process underlying 17 % of the inner ramus. Uropod 3: inner ramus with 1 spine mid-dorsally. Condition. Without antennae 1, right antenna 2, right pereopods 5 and 6, and both pereopods 7. Remaining right appendages (or left appendage when right lacking), telson, and mouthparts slide mounted. Other left appendages with the carcass. Description of adult female. Allotype: Length 5.1 mm. Character states as in the male except as follows. Antenna 1: overlapping antenna 2 to the end of article 5; article 5, posterior margin with long filter setae and a few plumose setae distally; flagellum, posterior margin with a few plumose setae proximally and brush setae distally. Gnathopod 2: propodus without a hinge tooth, palm 58 % the length of the posterior margin, setae plumose, so abundant as to obscure the palm’s shape. Condition. Without left pereopod 7. Variation. Maximum body length: male 5.3 mm, female 5.1 mm. Males of comparable body length to adult females have abundant plumose setae on the posterior margin of the second antennal article 5 and flagellum. Small males and juvenile females lack plumose setae on antenna 2 but bear long filter setae. The palm of gnathopod 2 is abundantly plumose in both adult females and comparably sized males and less so in small males and females. There is no evidence of thumb production in males of similar body length to adult females. There is some divergence in the gnathopod 2 propodus length between the sexes, with a greater length achieved by males than females of similar body length (Fig. 26).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA57D446FF1335F2D77EFCE3.taxon	materials_examined	Type material examined. Holotype, ♂, Rima Islet, The Snares, New Zealand (48 ° 07 ʹS, 166 ° 36 ʹE), in a crevice in the Durvillea zone, barnacles encrusted with sponge, 21 Nov. 1976, G. D. Fenwick, coll. (AM P. 34948, collection event SA- 3417). Allotype, ♀, same location (AM P. 37922). Paratypes, 5 adult ♂♂, 25 adult ♀♀, and 163 juveniles, same location (AM P. 37923). Other material examined. Alert Stack, The Snares, New Zealand (48 ° 07 ʹ S, 166 ° 36 ʹE), from algae below the Durvillea zone to 7 m depth, 20 Dec. 1976, G. D. Fenwick, coll., 2 juveniles (AM P. 34949, collection event SA- 3456).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA57D446FF1335F2D77EFCE3.taxon	etymology	Etymology. In gratitude to Dr. Jim Lowry (Australian Museum) for assistance in locating Southern Hemisphere material.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA57D446FF1335F2D77EFCE3.taxon	discussion	Remarks. The spination on the anterior margin of the basis of gnathopod 1 is not homologous with that of the Southern Hemisphere Jassa alonsoae Conlan, 1990, J. justi Conlan, 1990, J. fenwicki Conlan, 1990 and J. hartmannae Conlan, 1990 because it is medial instead of lateral. Readily recognizable differences between Pleojassa lowryi and P. moorei are listed in Table 4.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA51D445FF133211D49EFBE1.taxon	description	(Fig. 27)	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA51D445FF133211D49EFBE1.taxon	description	Description of male. (Not type; MfN 22.962, South Georgia, Swedish Antarctic Expedition): Length 8.0 mm. Antenna 2: overlapped by antenna 1 to midway along article 5; antenna 2, article 5 bearing simple setae only, these less than half the length of those of the female; flagellum 3 articles, article 1 86 % of full flagellum length. Mandible: palp articles 2 and 3 without a dorsal fringe of setae; raker spines 4 right, 6 left. Gnathopod 1: coxal margins, anterior 110 % of dorsal length, ventral margin shallowly concave; basis, anterior and posterior margins not setose; carpus, length 75 % of propodus length, posterior lobe 49 % of anterior margin length, anterodistal setal cluster short, 18 % of the anterior margin; propodus, palm convex, defining spine central. Gnathopod 2: coxal margins, anterior 30 % and posterior 72 % of ventral length, ventral margin convex and slightly sinuous; carpus less than 1 / 4 the length of propodus, posterior lobe with a short distal seta; propodus, hinge tooth large, conical, not bifid, palmar setae sparse throughout, thumb 30 % of article length, distally squared, tip with a minute defining spine, both inner and outer margins setose, posterior margin straight. Pereopod 3: coxa, greatest depth posterior of centre; basis, anterior margin shallowly concave; merus, anterior margin with 2 clusters of setae, these setae shorter than article width, article width 95 % of length; carpus 49 % overlapped by the merus; propodus, width 36 % of length. Pereopods 5 – 7: setae and spines moderately abundant, basis posterodistally produced, anterior margin spinose; merus, posterior margin not spinose. Uropod 1: peduncle, posteroventral spinous process underlying 38 % of the inner ramus, inner and outer rami with 14 and 17 mid-dorsal spines respectively. Uropod 2: peduncle, posteroventral spinous process underlying 27 % of the inner ramus. Uropod 3: inner ramus with two spines mid-dorsally. Condition. Previously dried. Without left antennae 1 and 2 flagella, right and left pereopod 7, and right uropod 1 outer ramus. Right appendages, both uropods 1, telson, and mouthparts slide mounted. Description of adult female. Lectotype (here designated): Length 7.7 mm. Character states as in the male except as follows. Antenna 2: article 5 without plumose setae. Gnathopod 2: propodus, hinge tooth pronounced, anterior margin crenulated, palmar setae dense throughout, sufficiently so to obscure the palm’s shape. Condition. Ovigerous. Previously dried. Without left pereopods 3, 6 and 7, and right pereopods 4 – 7. Variation. Maximum body length: male 8.0 mm, female 9.1 mm. The number of antennal articles is constant over body length and sex. Larger males show a shortening of the second antennal setae and a change in the shape of the second gnathopod palm (Fig. 27). The dactyl’s inner margin also changes shape from evenly convex to proximally expanded and sinuous.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA51D445FF133211D49EFBE1.taxon	materials_examined	Type material examined. Lectotype, ♀ (ZMH K- 8028) and paralectotypes (ZMH, K- 33618, K- 33620, K- 33622, K 033623, K- 33625, K- 33631 and K- 33632, all from K- 8028), station 7813, Moltke Hafen, Royal Bucht, South Georgia (54 ° 30 ʹ 58 ʺS, 36 ° 0 ʹ 45 ʺW), 1883, Deutsche Polar Commision, K. von den Steinen, coll. Other material examined. South Georgia: Moltke-Hafen (54 ° 30 ʹ 58 ʺS, 36 ° 0 ʹ 45 ʺW), Deutsche Polar Commission, 2 August 1899, 1 ♀, 1 juvenile (ZMH K- 8019); specific location not given, Deutsche Polar Commission, K. von den Steinen, coll., 16 January 1884, 2 ♀♀, 4 juveniles (ZMH K- 8021); stn. 7804, low ebb, K. von den Steinen, coll., 16 January 1884, Deutsche Polar Commission, K. von den Steinen, coll., 5 juveniles (ZMH K- 8017 A); Jason Hafen, station 19 (54 ° 14 ʹS, 36 ° 31 ʹW), 10 – 15 m depth, small stones, 23 April 1902, 1 juvenile (NRM 3676); Kochtopfbucht, Grytviken, station 35 (54 ° 22 ʹS, 36 ° 28 ʹW), 2 – 8 m depth, the inside edge of the Macrocystis formation, stone bottom, 12 June 1902, 1 juvenile (NRM 3677); mouth of the Moraine Fjord, 5 m depth, stone bottom, 15 January 1902, 1 ♀ (NRM 3678); specific location not given, Swedish Antarctic Expedition of 1901 – 1903, 1 ♂, 4 ♀♀, 13 juveniles (MfN 22.962).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA51D445FF133211D49EFBE1.taxon	discussion	Remarks. In his type description of Jassa multidentata, Schellenberg (1931) notes having examined specimens from the Swedish Museum of Natural History (collected in 1902, during the Swedish Antarctic Expedition of 1901 – 1903 from four locations in South Georgia), and from the Hamburg Museum (from South Georgia, but locations and collection dates not specified). Specimens examined for this study are listed above. The type designation is limited to the Hamburg material, selecting the 7.7 mm adult female of K- 8028 as lectotype. Pertinent additional information on this sample was provided by H. Petersen, ZMH, 15 January 1988: “ The material from K- 8028 = Jassa multidentata Schellenberg, 1931 is, however, originally derived from the sample K- 8017 = Jassa ingens Pfeffer. Since Schellenberg was also at the disposal of the material from the German Station in South Georgia (in 1882 - 1883) with the compiled Amphipod material from Pfeffer, we are assuming that Schellenberg has presented the material from Jassa ingens to Pfeffer only for comparison. It is presumed that Schellenberg separated from this sample - which also had been revised earlier by Chilton - Specimen which belonged to Jassa multidentata. It would be advisable to point that this location is not mentioned in the original description from Schellenberg (1931). By this, we are presuming that the material has really been presented to Schellenberg during the time of determination. ” Pleojassa multidentata differs from P. orientalis in the shape of the gnathopod 2 palm (both sexes) (Figs 27 and 28), and by possessing a cluster of short setae at the anterodistal margin of the carpus of gnathopod 1, which is absent in P. orientalis. Pleojassa multidentata is only known from South Georgia while P. orientalis is only known from Macquarie Island (Fig. 2).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA53D45BFF133385D102FF23.taxon	description	(Fig. 28) Description of adult female. Holotype: Length 9.8 mm. Antenna 2: overlapped by antenna 1 to the end of article 5; article 5, posterior margin bearing long simple setae only, without plumose setae; flagellum 3 articles, article 1 89 % of the full flagellum length. Mandible: palp articles 2 and 3 without a dorsal fringe of setae; raker spines, number not measured. Gnathopod 1: coxal margins, anterior 140 % of dorsal length; ventral margin shallowly convex; basis, anterior margin with a few short setae distally, posterior margin not setose; carpus, length 75 % of propodus length, posterior lobe 59 % of anterior margin length, without an anterodistal setal cluster; propodus, palm convex, with two defining spines slightly proximal of centre. Gnathopod 2: coxal margins, anterior 44 % and posterior 73 % of ventral length; ventral margin shallowly concave; carpus less than 1 / 4 the length of propodus; propodus, hinge tooth large and conical, not anteriorly bifid, palmar setae plumose, distributed throughout the palm, but not so dense as to obscure the palm’s shape, palmar angle acute, with a single, minute spine at its corner; dactyl, inner margin slightly sinuous. Pereopod 3: coxa, greatest depth posterior of centre; basis, anterior margin shallowly convex; merus, anterior marginal setae in well separated clusters, central setae, length 1 / 2 or less the article width, article width 72 % of length; carpus 42 % overlapped by merus; propodus, width 48 % of length. Pereopods 5 – 7: setae and spines moderately abundant, basis posterodistally produced, anterior margin spinose; merus, posterior margin not spinose. Uropod 1: peduncle, posteroventral spinous process underlying 52 % of the inner ramus, inner and outer rami with 10 and 6 mid-dorsal spines respectively. Uropod 2: peduncle, posteroventral spinous process underlying 42 % of the inner ramus. Uropod 3: inner ramus with 2 spines mid-dorsally. Condition. Without left pereopod 5 and right pereopod 6. Flagellum of right antenna 1 lacking terminal article (s). Right appendages, left pereopod 6, and telson slide mounted. Description of male. Allotype: Length approximately 6.5 mm; head to end of segment 6, 3.9 mm. Character states as in the female except as follows. Antenna 2: article 5, filter setae half or less the length of those in the female, interspersed with plumose setae. Gnathopod 2: as in the female, but palm less densely setose and dactyl inner margin straight. Condition. Without body segments posterior of segment 6, antennae 1 flagella, left antenna 2 distal flagellum, right antenna 2, left pereopods 5 – 7, and right pereopods 5 and 7. Variation. Maximum body length: male unknown, female 9.8 mm. The male is 2 / 3 the body length of the adult female holotype (judging by relative difference in head length). This suggests that this male may not yet be mature, so it cannot be assumed that larger males lack a thumb as illustrated for the smaller male. Due to lack of material, sexual variation and growth is not well known and only can be inferred from congeners. Judging by its close resemblance to P. multidentata, in which the male is known to grow a thumb, this development is probably similar in P. orientalis. The small male bears plumose setae on the antenna 2 while the adult female lacks plumose setae. However, as in P. wandeli, larger females may have plumose setae.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA53D45BFF133385D102FF23.taxon	materials_examined	Type material examined. Holotype, ♀, ovigerous (AM), type no. P. 34955, station no. MA- 147, Macquarie Island: Gorilla Head Rock, southeast corner (54 o 29 ʹS, 158 o 58 ʹE), 23 December 1977, in a small Durvillea antarctica holdfast, 8 m. Allotype, small (juvenile?) ♂ (AM), type no. P. 37924, same location. Paratype, juvenile ♀ (AM), type no. P. 37925, same location.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA53D45BFF133385D102FF23.taxon	etymology	Etymology. In reference to the eastern location of the species relative to P. multidentata.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA53D45BFF133385D102FF23.taxon	discussion	Remarks. Pleojassa orientalis differs from P. multidentata in the shape of the gnathopod 2 palm (both sexes) (Figs 27 and 28), and in lacking a cluster of short setae at the anterodistal margin of the carpus of gnathopod 1, which is present in P. multidentata. Pleojassa orientalis may prove to be a geographic variant of P. multidentata, given the wide longitudinal range that Southern Hemisphere species can have (Figs 1 and 2). They are given separate species status herein because these morphological differences are key characters for distinguishing species in Jassa (Conlan et al., in press) and this may be the same case in Pleojassa and other relatives of Jassa.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA4DD452FF133642D185FD73.taxon	description	(Figs 29 – 34)	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA4DD452FF133642D185FD73.taxon	description	Description of male. (Not type; Billie Rocks, Signy Island, South Orkney Islands, 5 March 1965, M. H. Thurston, coll. (NHM 1969: 735: 39 station 10 (95 )). Length 9.8 mm. Antenna 2: overlapped by antenna 1 to midway along article 5; article 5 and flagellum, posterior margin covered in a mass of plumose setae; simple setae absent; flagellum 3 articles, the last half the length of the second; article 1 87 % of full flagellum length. Mandible: palp articles 2 and 3 without a dorsal fringe of setae; raker spines 4 right, 5 left. Gnathopod 1: coxal margins, anterior 113 % of dorsal length; ventral margin straight; basis, anterior margins with a few fine setae spaced along their length, posterior margin with a single distal seta; carpus, length 65 % of propodus length, posterior lobe 50 % of anterior margin length, anterodistal setal cluster short, 39 % of the anterior margin length; propodus, palm convex, with one defining spine slightly proximal of centre. Gnathopod 2: coxal margins, anterior 21 % and posterior 83 % of ventral length, ventral margin straight; carpus less than a quarter the length of the propodus, posterior lobe without a distal seta; propodus, palm, hinge tooth rectangular cuboid, shallowly bifid centrally, setae sparse but spread throughout the palm, thumb 36 % of propodus length, distally squared, posterior margin straight, with clusters of setae subapically, and 3 groups posteriorly, and with 1 minute defining spine at its tip. Pereopod 3: coxa, greatest depth at the centre; basis, anterior margin straight; merus, anterior marginal setae in discrete, well spaced clusters, about a third the article width, article width 61 % of length; carpus 44 % overlapped by the merus; propodus, width 56 % of length. Pereopods 5 – 7: setae and spines moderately abundant, basis posterodistally produced, anterior margin spinose; merus, posterior margin not spinose. Uropod 1: peduncle, posteroventral spinous process underlying 38 % of the inner ramus, inner and outer rami with 7 and 13 mid-dorsal spines respectively. Uropod 2: peduncle, posteroventral spinous process underlying 10 % of the inner ramus. Uropod 3: inner ramus with 2 dorso-medial spines. Condition. Without the left pereopod 5. Right appendages, telson and mouthparts slide mounted. Remaining appendages with the carcass. Description of adult female. (Not type; same location as for the male). Length 9.6 mm. Character states as in the male except as follows. Antenna 2: article 5, posterior margin with long simple setae mainly, but interspersed with a few plumose setae. Gnathopod 2: coxal margins, anterior 56 % and posterior 94 % of ventral length, ventral margin convex; propodus, hinge tooth strongly pronounced, palmar setae densely plumose throughout, so much so as to nearly obscure the shape of the palm. Condition. With all appendages. Right appendages, telson, and mouthparts slide mounted. Left appendages with the carcass. Variation. Maximum body length: male 10.8 mm, female 9.7 mm. In small individuals of both sexes, the filter setae on antenna 2 are long and plumose setae are absent. In the adult female, these long filter setae are also present along with some plumose setae on the flagellum (Fig. 33). In larger males, with or without thumbs, the filter setae are shorter and mixed with dense plumose setae. In the specimens available, plumose setae were evident at Ξ 5.5 mm body length. Males of a single population appeared to show a linear increase in antenna 2 article 5 length with body length (Fig. 31). Large males have long thumbs on the propodus of gnathopod 2 but unlike Jassa, development may be gradual over more than one molt (Conlan, 1989). This is indicated in the short thumbed male in Fig. 30, where a somewhat longer thumb was visible inside the cuticle. In Jassa, a thumb that is visible within the cuticle is always much longer than the subadult’s small “ pre-thumb ” (Conlan et al. in press). The thumb develops at the location of the single palmar defining spine. This spine, though small, can be seen at the tip of the thumb, even on some long-thumbed specimens. In the population graphed, the gnathopod 2 propodus was longer in the males than females of the same length (Fig. 32) and the relationship to body length appears to be linear in both sexes (although lack of mid-sized specimens in the males caused failure of the Durbin-Watson statistic for independent residuals and the Constant Variance Test using Spearman rank correlations). The shape of the gnathopod 2 dactyl margin also varies. In females of all sizes and in small males, the inner margin is straight. In males with a long thumb, the dactyl is curved and proximally produced (Fig. 30).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA4DD452FF133642D185FD73.taxon	materials_examined	Type material examined. Lectotype (here designated), ♂, Ile Booth-Wandel, Antarctica, 10 December 1904, Mission Charcot, among sponges at low tide, Expédition Antarctique Française (1903 – 1905) (MNHN, catalogue no. Am. 2630 (1 )). Paralectotypes, 1 ♀, 13 juveniles, same location. Other material examined. (excluded from type series): South Georgia: Royal Bucht, Moltke Hafen (54 ° 15 ʹS, 36 ° 0 ʹ 45 ʺW), 31 Aug. 1883, K. von den Steinen, coll., Deutsche Polar Commision 1882 – 1883, 1 juvenile (ZMH K- 32085 ex 22473). South Sandwich Group: Visokoi I. (56 ° 42 ʹS, 27 ° 12 ʹW), 13 Nov. 1908, C. A. Larsen, coll., 18 – 31 m depth, 1 ♀ (MfN), 1 juvenile (UiO F 2973). Petermann I.: Pourquoi Pas?, Antarctica 1908 – 1910, 2 e Mission Charcot 1912, 1 Nov. 1909, 1 ♂, 1 ♀ (MNHN Am. 2628); Pourquoi Pas?, Antarctica 1908 – 1910, 2 e Mission Charcot 1912, 16 Nov. 1909, M. le Dr. Liouville, coll., 6 ♂♂, 2 ♀♀ (MNHN Am. 2627). South Shetland Islands: Deception I. (62 ° 57 ʹS, 60 ° 38 ʹW), 17 Dec. 1927, C. Olstad, coll., 25 m depth, Norvegia Expedition No. 58, ~ 15 individuals, not sexed (UiO F 2970), Kerguelen I.: S. baie du Morbihan, Port-Douzième, Durvillea antarctica holdfast, 13 Feb. 1966, J. C. Hureau, coll., littoral (D. Bellan-Santini loan), 1 ♂. South Orkney Islands: 46 collections from Billie Rocks, Berntsen Point, Elephant Flats, and Factory Cove, Signy Island, Dec., Apr. and June 1964 and Feb. – Apr. 1965, ~ 230 specimens, M. H. Thurston, coll. (NHM stations 1, 3, 4, 10, 13, 15 – 20, 22 – 26, 29, 30, 32, 33, 35, 46, 49 and 51).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA4DD452FF133642D185FD73.taxon	discussion	Remarks. Pleojassa wandeli resembles P. multidentata in thumb development and overall appearance. The latter can be distinguished by the shorter seta at the anterodistal junction of the carpus and propodus of gnathopod 1, lack of antenna 2 plumosity in the adult, denser plumosity of the gnathopod 2 palm in the female and juvenile, more pronounced hinge tooth, and pronounced uropod 2 peduncular process. Chevreux (1913) listed an additional specimen collected on Petermann Island at Port-Circoncision, 10 Oct. 1909, collected at 6 m depth from algae. This has not been seen but the other two collections listed were examined (listed above), which includes the long thumbed male illustrated by Chevreux (1913). A smaller male from Petermann Island (collected 16 Nov. 1909), showing an internal thumbed cuticle is illustrated in Fig. 30. Schellenberg (1926) may have been describing P. wandeli when he listed “ Jassa falcata ” from Kerguelen Island, collected in January 1902 during the Deutsche S ̹ dpolar-Expedition 1901 – 1903. Although not seen, these specimens are within the size range and location known for P. wandeli (females adult at 7 – 9.5 mm). This would make the first known collection of P. wandeli from Kerguelen Island much earlier than the 1966 collection of “ Jassa falcata ” lent by D. Bellan-Santini and confirmed to be P. wandeli (Table 2). Additional collections of “ Jassa falcata ” from Kerguelen and Crozet Islands reported by Bellan-Santini & Ledoyer (1973, 1974) are likely P. wandeli as well. No other species of Pleojassa, Hemijassa or Jassa are known from these islands. This would also expand the known range of P. wandeli to the Crozet Islands. Thurston (1974 b) collected 572 specimens at Signy Island, naming them “ Jassa falcata form 1 ”. Many of these were examined for this study and are confirmed P. wandeli. Thurston (1974 a) noted that his “ Jassa falcata ” from Deception Island (Γ 62.98 ° S 60.65 ° W), Hope Bay (63.3833 ° S, 56.9833 ° W), Port Lockroy (64.8252 ° S, 63.4945 ° W) and the Argentine Islands (65.25 ° S, 64.27 ° W) agreed with Chevreux’ (1906) description and figures of Pleojassa wandeli. Kim et al. (2014) found P. wandeli in a scuba collection at 20 – 30 m depth in Marian Cove, King George Island (62 ° 12 ʹ 06.48 ʺS, 58 ° 44 ʹ 03.14 ʺW). They included a photograph of the left lateral side of a live animal, showing the dorsum, coxae, antennae and distal part of the gnathopods pigmented dark brown. There was a contrasting reduced or lack of pigmentation around the edges of the articles, on the proximal parts of the gnathopods, and on the pereopods.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA44D453FF133350D002FAD7.taxon	description	Supplementary Table S 2	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA44D453FF133350D002FAD7.taxon	type_taxon	Type genus. Ischyrocerus Krøyer, 1838	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA44D453FF133350D002FAD7.taxon	diagnosis	Diagnosis (with changes from Just (2017) in bold). Antennae: slender, antenna 1 with accessory flagellum (occasionally vestigial). Mandible: palp with 3 articles, the third expanded distally (occasionally similar in shape to the second). Coxae 1 – 4: progressively deepening, subrectangular to oval (occasionally coxa 1 much smaller than and mostly obscured by coxa 2 and differing in shape), margins entire. Gnathopod 1: carpus shorter than the propodus (occasionally longer), propodus oval to weakly subchelate. Gnathopod 2: propodus in adult male (and occasionally in the female) moderately to strongly enlarged compared to gnathopod 1, of varying shape (occasionally hardly modified). Pereopods 3 – 4: merus moderately to fully overlapping the carpus anteriorly, dactyl shorter than the carpus (occasionally longer). Pereopods 5 – 7: of similar form, increasing in length backwards (occasionally 6 larger than 5 and 7). Urosomites: 1 – 3 free. Uropods 1 and 2: peduncle without distoventral corona of spines, with 2 subequal rami with or without an underlying peduncular spinous process (occasionally uropod 2 outer ramus modified). Uropod 3: peduncle long (occasionally short), broad proximally, narrow distally, biramous (occasionally uniramous), outer ramus terminating in cusps and / or spine (s). Telson: entire, with one to many dorsally or apically projecting setae or spines. Component genera. Jassa Leach, 1814; Ischyrocerus Krøyer, 1838; Paradryope Stebbing, 1888; Microjassa Stebbing, 1899; Parajassa Stebbing, 1899; Hemijassa Walker, 1907; Isaeopsis K. H. Barnard, 1916; Pseudischyrocerus Schellenberg, 1931; Bathyphotis Stephensen, 1944; Ventojassa J. L. Barnard, 1970; Neoischyrocerus Conlan, 1995; Scutischyrocerus Myers, 1995; Ruffojassa Vader & Myers, 1996; Veronajassa Vader & Myers, 1996; Alatajassa Conlan, 2007; Myersius Souza-Filho & Serejo, 2014; Pleojassa n. gen.; Plumulojassa n. gen. Changes to Ischyrocerus and Neoischyrocerus Ischyrocerus is primarily a cold water, Northern Hemisphere genus, captured from deep trawls (Stephensen 1944; Gurjanova 1951) as far north as the high Arctic, but also found in the intertidal and shallow subtidal zone (J. L. Barnard 1962). It has been extensively found in the Southern Hemisphere as well, though mostly in warmer waters (Myers 1995, 1997; Just 2009). This large genus requires revision and may prove to be less cosmopolitan than previously thought by J. L. Barnard & Karaman (1991). Three genera have been created for warm water Ischyrocerus - like species: Neoischyrocerus Conlan, 1995 (4 species), Coxischyrocerus Just, 2009 (2 species) and Tropischyrocerus Just, 2009 (2 species). These genera embrace species in which the male develops an enormously lengthened and pendulous gnathopod 2 (about 200 – 300 % the length of gnathopod 1) with an anteriorly rounded ischium and a very long propodus with the palm nearly the full length of the propodus, and the proximal end of the palm marked by a bulge next to the carpus (the S. Californian N. claustris (J. L. Barnard, 1969), N. chinipa (J. L. Barnard, 1979) from the Galapagos and Pacific Panama, N. vidali Ortiz & Lalana, 2002 from the Cuban Caribbean, C. inexpectatus (Ruffo, 1959) from the Mediterranean Sea and T. socia (Myers, 1989) from Bora Bora), a tooth-like projection (e. g., N. lilipuna (J. L. Barnard, 1970) from Hawaii and T. pugilus Just, 2009 from Australia), or with neither (e. g., C. rhombocoxus Just, 2009 from Australia). The dactyl may be the full length of the propodus or shorter, the length growth related. By comparison, the female’s gnathopods are similarly sized with the second only slightly larger than the first. Other commonalities are antennae with long filtering setae that are not pediform or sexually dimorphic, a 2 - articulate accessory flagellum with the second article minute, pereopods 3 and 4 with little overlap of the merus over the carpus, a well developed peduncular spinous process under the rami of uropod 1, a spiny peduncle of uropod 3 with the outer ramus bearing a row of minute cusps and the inner ramus tipped by a small spine, and the telson with a pair of strong, dorsally projecting spines. The difficulty with these genera is where species cross the generic boundaries. Examples are: enlarged coxa 2 relative to coxa 1 in the adult male (C. rhombocoxus and N. claustris), similar gnathopod propodus appearance as noted above, and similar female gnathopod palms (convex in all species in the three genera except for T. pugilus), pereopod 3 and 4 propodus posteriorly spinose (N. lilipuna, N. vidali, T. socia and C. inexpectatus). The generic-level differences among the genera therefore recede into issues of sexual variation (e. g., enlargement of coxa 2 relative to coxa 1 that was used to define Coxischyrocerus but also occurs in Neoischyrocerus, or the modified pereopod 5 basis shape in adult males of C. rhombocoxus and C. inexpectatus). Therefore, Coxischyrocerus Just, 2009 and Tropischyrocerus Just, 2009 are herein merged into the senior genus Neoischyrocerus Conlan, 1995. Myers (1995, 1997) noted the need for diminutive Indo-Pacific species placed at that time in Ischyrocerus or Jassa to be placed in their own genus and these are also included, as noted below.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA44D453FF133350D002FAD7.taxon	diagnosis	Diagnosis (with changes from Just (2017) in bold).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA44D453FF133350D002FAD7.taxon	description	Antennae: slender, antenna 1 with accessory flagellum (occasionally vestigial). Mandible: palp with 3 articles, the third expanded distally (occasionally similar in shape to the second). Coxae 1 – 4: progressively deepening, subrectangular to oval (occasionally coxa 1 much smaller than and mostly obscured by coxa 2 and differing in shape), margins entire. Gnathopod 1: carpus shorter than the propodus (occasionally longer), propodus oval to weakly subchelate. Gnathopod 2: propodus in adult male (and occasionally in the female) moderately to strongly enlarged compared to gnathopod 1, of varying shape (occasionally hardly modified). Pereopods 3 – 4: merus moderately to fully overlapping the carpus anteriorly, dactyl shorter than the carpus (occasionally longer). Pereopods 5 – 7: of similar form, increasing in length backwards (occasionally 6 larger than 5 and 7). Urosomites: 1 – 3 free. Uropods 1 and 2: peduncle without distoventral corona of spines, with 2 subequal rami with or without an underlying peduncular spinous process (occasionally uropod 2 outer ramus modified). Uropod 3: peduncle long (occasionally short), broad proximally, narrow distally, biramous (occasionally uniramous), outer ramus terminating in cusps and / or spine (s). Telson: entire, with one to many dorsally or apically projecting setae or spines. Component genera. Jassa Leach, 1814; Ischyrocerus Krøyer, 1838; Paradryope Stebbing, 1888; Microjassa Stebbing, 1899; Parajassa Stebbing, 1899; Hemijassa Walker, 1907; Isaeopsis K. H. Barnard, 1916; Pseudischyrocerus Schellenberg, 1931; Bathyphotis Stephensen, 1944; Ventojassa J. L. Barnard, 1970; Neoischyrocerus Conlan, 1995; Scutischyrocerus Myers, 1995; Ruffojassa Vader & Myers, 1996; Veronajassa Vader & Myers, 1996; Alatajassa Conlan, 2007; Myersius Souza-Filho & Serejo, 2014; Pleojassa n. gen.; Plumulojassa n. gen.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA44D453FF133350D002FAD7.taxon	discussion	Ischyrocerus is primarily a cold water, Northern Hemisphere genus, captured from deep trawls (Stephensen 1944; Gurjanova 1951) as far north as the high Arctic, but also found in the intertidal and shallow subtidal zone (J. L. Barnard 1962). It has been extensively found in the Southern Hemisphere as well, though mostly in warmer waters (Myers 1995, 1997; Just 2009). This large genus requires revision and may prove to be less cosmopolitan than previously thought by J. L. Barnard & Karaman (1991). Three genera have been created for warm water Ischyrocerus - like species: Neoischyrocerus Conlan, 1995 (4 species), Coxischyrocerus Just, 2009 (2 species) and Tropischyrocerus Just, 2009 (2 species). These genera embrace species in which the male develops an enormously lengthened and pendulous gnathopod 2 (about 200 – 300 % the length of gnathopod 1) with an anteriorly rounded ischium and a very long propodus with the palm nearly the full length of the propodus, and the proximal end of the palm marked by a bulge next to the carpus (the S. Californian N. claustris (J. L. Barnard, 1969), N. chinipa (J. L. Barnard, 1979) from the Galapagos and Pacific Panama, N. vidali Ortiz & Lalana, 2002 from the Cuban Caribbean, C. inexpectatus (Ruffo, 1959) from the Mediterranean Sea and T. socia (Myers, 1989) from Bora Bora), a tooth-like projection (e. g., N. lilipuna (J. L. Barnard, 1970) from Hawaii and T. pugilus Just, 2009 from Australia), or with neither (e. g., C. rhombocoxus Just, 2009 from Australia). The dactyl may be the full length of the propodus or shorter, the length growth related. By comparison, the female’s gnathopods are similarly sized with the second only slightly larger than the first. Other commonalities are antennae with long filtering setae that are not pediform or sexually dimorphic, a 2 - articulate accessory flagellum with the second article minute, pereopods 3 and 4 with little overlap of the merus over the carpus, a well developed peduncular spinous process under the rami of uropod 1, a spiny peduncle of uropod 3 with the outer ramus bearing a row of minute cusps and the inner ramus tipped by a small spine, and the telson with a pair of strong, dorsally projecting spines. The difficulty with these genera is where species cross the generic boundaries. Examples are: enlarged coxa 2 relative to coxa 1 in the adult male (C. rhombocoxus and N. claustris), similar gnathopod propodus appearance as noted above, and similar female gnathopod palms (convex in all species in the three genera except for T. pugilus), pereopod 3 and 4 propodus posteriorly spinose (N. lilipuna, N. vidali, T. socia and C. inexpectatus). The generic-level differences among the genera therefore recede into issues of sexual variation (e. g., enlargement of coxa 2 relative to coxa 1 that was used to define Coxischyrocerus but also occurs in Neoischyrocerus, or the modified pereopod 5 basis shape in adult males of C. rhombocoxus and C. inexpectatus). Therefore, Coxischyrocerus Just, 2009 and Tropischyrocerus Just, 2009 are herein merged into the senior genus Neoischyrocerus Conlan, 1995. Myers (1995, 1997) noted the need for diminutive Indo-Pacific species placed at that time in Ischyrocerus or Jassa to be placed in their own genus and these are also included, as noted below.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA45D450FF133257D472F9F7.taxon	diagnosis	Genus Neoischyrocerus n. comb. Supplementary Table S 3	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA45D450FF133257D472F9F7.taxon	description	Supplementary Table S 3	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA45D450FF133257D472F9F7.taxon	type_taxon	Type species. N. claustris J. L. Barnard, 1969	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA45D450FF133257D472F9F7.taxon	diagnosis	Diagnosis. (with differences from Ischyrocerus in bold). Body length at maturity 1 – 2 mm (usually), rarely 4 – 6 mm. Tropical and warm temperate distribution, collected from algae, sponges, corals or from a spiny lobster, 0 – 16 m, 9 – 40 ° N and 5 – 34 ° S.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA45D450FF133257D472F9F7.taxon	description	Pereon: dorsally smooth (most species), ridged or carinate (some species). Antenna 1: accessory flagellum 2 articles (second minute), projecting forward or flush with the flagellum; antennae 1 and 2 peduncles subequal in width or antenna 2, 10 % wider (based on comparison of antenna 1 peduncle article 2 with antenna 2 peduncle article 4), peduncular setae and setal pattern similar to antenna 1, or slightly shorter, not plumose. Gnathopod 2, adult male: 190 – 350 % the length of gnathopod 1, basis and propodus especially elongate; coxa 1, 60 – 110 % the depth of coxa 2; basis concave or sinuous; ischium anteriorly rounded; propodus often slender (posterior length 180 – 400 % of central width), palm nearly the full length of the propodus, often with a bulge or tooth defining it proximally at the junction of the carpus (sometimes palm continuous with the carpus), sometimes centrally toothed instead and with shallow bulge or teeth at the junction of the dactyl; dactyl half or nearly the full length of the propodus. Gnathopod 2, juvenile male: shorter than the adult male gnathopod 2, palm bearing 1 – 2 strong spines about midway along the length of the propodus, dactyl ending at the spines. Gnathopod 2, female: only slightly larger than gnathopod 1, palm of the propodus convex (usually) or shallowly concave (rarely). Pereopods 3 and 4: propodus, posterior margin bearing spines or setae; coxa 4, posterior margin straight, not shallowly concave. Pereopod 5, male: similar to but shorter than pereopods 6 and 7 or variously modified with posteriorly concave basis or posteriorly expanded and spinose merus. Uropod 1: peduncle with short ventrodistal spinous process underlying the rami, length ~ 15 – 35 % of the outer ramus length. Uropod 3: peduncle bearing 1 – 2 rows of spines dorsally, ending in a single spine at the distal margin, but without a corona of spines around the margin or setae; rami without spines mid-dorsally, outer ramus subequal to or shorter than the inner and bearing 3 – 8 minute dorsal cusps apically, without (rarely with) a small apical straight spine. Component species (with transferred species in bold). Ischyrocerus longimanus (Haswell, 1879) (Australia); I. parvus Stout, 1913 (California); I. carinatus K. H. Barnard, 1916 (South Africa); I. gorgoniae K. H. Barnard, 1940 (South Africa); I. ctenophorus Schellenberg, 1953 (South Africa); Coxischyrocerus inexpectatus (Ruffo, 1959) (Mediterranean, Red Sea?); N. claustris J. L. Barnard, 1969 (California); N. lilipuna J. L. Barnard, 1970 (Hawaii); I. oahu J. L. Barnard, 1970 (Hawaii); I. oahu oahu J. L. Barnard, 1970 (Hawaii); N. chinipa J. L. Barnard, 1979 (Galapagos Islands and Panama); I. oahu armatus Ledoyer, 1979 (Madagascar); Tropischyrocerus socia (Myers, 1989) (Bora Bora); I. mediodens Myers, 1995 (Papua New Guinea); I. parma Myers, 1995 (Papua New Guinea); I. apiensis Myers, 1997 (Samoa); N. vidali Ortiz & Lalana, 2002 (Cuba); C. rhombocoxus Just, 2009 (Australia); T. pugilus Just, 2009 (Australia).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA45D450FF133257D472F9F7.taxon	discussion	Remarks. Species of Ischyrocerus were transferred to Neoischyrocerus if they demonstrated at least one key character (grossly enlarged and pendulous male gnathopod 2 similar in shape to that of others in the genus; dactyls with comb-like striae as noted in J. L. Barnard (1970), Conlan (1995) and Ortiz & Lalana (2002); similar spination on uropod 3). Presence or absence of these striae were not mentioned by other authors, therefore questioning as to whether this character had been looked for. Mouthpart characteristics were not widely described, but may be useful for generic definition, especially the clavate vs slenderer shape of the mandibular palp and the presence / absence of a long apical seta on the maxilla 1 inner plate. Excluded but uncertain generic status. Ischyrocerus kapu J. L. Barnard, 1970 from Hawaii. The author based the generic assignment on a single male specimen. He noted its resemblance to N. lilipuna but also considered that it should be in a new genus. On balance, though, he assigned it to Ischyrocerus but noted that this was based on limited information because the specimen lacked antennae and pereopods and the female was also unknown. The male’s gnathopod 2 is unusual in having a long conical extension of the merus underneath the propodus, a feature that is not known for either Ischyrocerus or Neoischyrocerus. Myers (1995) stated that I. kapu is congeneric with other species being transferred to Neoischyrocerus. The male’s propodus is wider than in other members of Neoischyrocerus, but its uropod 3 resembles other species of Neoischyrocerus rather than Ischyrocerus. Further material demonstrating the species’ complete morphology is required before it can be confidently transferred to Neoischyrocerus or to a new genus.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA46D456FF133176D47BFAFC.taxon	discussion	Genus Ischyrocerus n. comb. Supplementary Table S 4	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA46D456FF133176D47BFAFC.taxon	description	Supplementary Table S 4	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA46D456FF133176D47BFAFC.taxon	type_taxon	Type species. Ischyrocerus anguipes Krøyer, 1838	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA46D456FF133176D47BFAFC.taxon	diagnosis	Diagnosis (with differences from Neoischyrocerus in bold). Body length at maturity 2 – 18 mm, though most species are> 5 mm long at adulthood. Primarily known from the Northern Hemisphere in cold temperate to polar waters from 32 ° N (La Jolla, California; J. L. Barnard 1969) to 81 ° N in the Arctic Ocean (Stephensen 1944), collected from algae, hydroids, crabs or substrate unknown, 1 to ~ 2000 m. Widely known in Europe but not in the Southern Hemisphere, although one species was found at 42 ° S off of Chile (J. L. Barnard 1964).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA46D456FF133176D47BFAFC.taxon	description	Pereon: dorsally smooth (most species), ridged or carinate (some species). Antenna 1: accessory flagellum 2 articles (second minute), flush with the flagellum or rarely projecting forward; antenna 2 peduncle article 4, 115 – 170 % wider than antenna 1 peduncle article 2 (or rarely equal width), setae and setal pattern similar to antenna 1 or setae shorter, occasionally plumose. Gnathopod 2, adult male: 100 – 220 % the length of gnathopod 1, basis usually not especially elongate, propodus elongate and slender or short and broad (rarely similar to gnathopod 1); coxa 1 70 – 140 % the depth of coxa 2; basis concave or straight; ischium anteriorly rounded or straight; propodus variably shaped, slender or broad (posterior length 120 – 290 % of central width), palm only on the distal portion of the propodus or nearly the full length of the propodus, without a bulge or tooth defining it proximally at the junction of the carpus, palm variously toothed; dactyl 33 – 75 % the length of the propodus. Gnathopod 2, juvenile male: shorter than the adult male gnathopod 2, palm bearing 1 – 2 strong spines about midway along the length of the propodus, dactyl ending at the spines. Gnathopod 2, female: only slightly larger than gnathopod 1, palm of the propodus convex or concave. Pereopods 3 and 4: propodus, posterior margin bearing setae but not spines; c oxa 4, posterior margin straight to shallowly concave. Pereopod 5, male: similar to but shorter than pereopods 6 and 7 or basis posteriorly concave; merus not differing. Uropod 1: peduncle with short ventrodistal spinous process underlying the rami, length ~ 25 – 50 % of the outer ramus length. Uropod 3: peduncle bearing 0 – 2 rows of spines dorsally, ending in a corona of spines at the distal margin (rarely a single seta or single spine); rami with 0 – 1 spines (outer), 0 – 4 spines (inner), outer ramus subequal to a third shorter than the inner and bearing 0 – 9 cusps, occasionally with 1 – 2 apical spines that are straight or dorsally recurved. Component species. Ischyrocerus anguipes Krøyer, 1838 (N. Europe and Arctic Ocean); I. latipes Krøyer, 1842 (Arctic Ocean); I. minutus Liljeborg, 1851 (N. Europe); I. megacheir (Boeck, 1871) (40 ° N – 80 ° N, Atlantic to Arctic Ocean); I. brevicornis (Sars, 1879) (E. Greenland, Arctic Ocean); I. tuberculatus (Hoek, 1882) (Barents Sea, 71 ° N – 77 ° N); I. tenuicornis (Sars, 1885) (N. Europe); I. nanoides (Hansen, 1887) (Arctic, Baffin Bay and W Greenland, 61 ° N – 81 ° N); I. megalops Sars, 1894 (N. Europe); I. commensalis Chevreux, 1900 (E. Atlantic Canada and Saguenay Fjord); I. brusilovi Gurjanova, 1933 (Russian waters); I. enigmaticus Gurjanova, 1934 (Kara Sea, 78 ° 58 ʹN); I. cristatus Gurjanova, 1938 (Sea of Japan); I. elongatus Gurjanova, 1938 (Sea of Japan); I. rhodomelae Gurjanova, 1938 (Sea of Japan); I. serratus Gurjanova, 1938 (Sea of Japan); I. hanseni Stephensen, 1944 (64 ° N, between Iceland and Greenland); I. albanovi Gurjanova, 1946 (Arctic Ocean); I. laptevi Gurjanova, 1946 (Arctic Ocean); I. chamissoi Gurjanova, 1951 (Russian waters); I. dezhnevi Gurjanova, 1951 (Russian waters); I. krascheninnikovi Gurjanova, 1951 (Russian waters); I. stephenseni Gurjanova, 1951 (Russian waters); I. pelagops J. L. Barnard, 1962 (California); I. hortator J. L. Barnard, 1964 (off Chile); I. malacus J. L. Barnard, 1964 (California); I. gurjanovae Kudrjaschov, 1975 (Kurile Islands); I. tzvetkovae Kudrjaschov, 1975 (Kurile Islands); I. fractus King & Holmes, 2004 (Ireland).	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
03DFE565EA46D456FF133176D47BFAFC.taxon	discussion	Remarks. Species were retained in Ischyrocerus if they lacked the key characters noted above for Neoischyrocerus in the appearance of the male gnathopod 2, pereopod dactyls or uropod 3 spination pattern. Ischyrocerus fractus is the only species known in this genus where the male’s gnathopod 2 propodus is very little different from the female’s. It is also the smallest known at adulthood for this genus (2 mm). Excluded, but uncertain generic status. Ischyrocerus camptonyx Thurston, 1974 b from subantarctic Signy Island is not Ischyrocerus. It is possibly an undescribed species of Jassa or synonymous with J. alonsoae, in which case Thurston’s name would take precedence. Jassa thurstoni Conlan, 1990 (called J. falcata form 2 by Thurston) and Pleojassa moorei n. sp. (called J. falcata form 3) are also known from Thurston’s collections there. For I. camptonyx, hallmarks of the genus Jassa, rather than Ischyrocerus are the spines at the tip of the antenna 2, the sinuous palmed gnathopod 2, the strong overlap of the merus over the carpus on pereopods 3 and 4, the typical Jassa - like uropod 3 with long peduncle lacking mid-dorsal spines (but with a corona of spines around the distal margin), a lateral setal brush and the strong hooked spines at the tip of the outer ramus, and the telson with a long seta at each corner rather than a spine. However, Thurston describes the uropod outer ramus “ with three stout hooked spines dorsally near apex and a minute comb with five-six teeth laterally ”, which does not correspond to his illustration and are not Jassa - like. Possibly, though, his description could be interpreted differently. One of the three spines may be the apically immersed, dorsally recurved spine typical of Jassa, the other two spines are cusps, and the five – six teeth are minute dorsal cusps proximal to the two large ones. If so, then this also speaks of I. camptonyx as being a Jassa, either its own species or synonymous with J. alonsoae. It is not a Pleojassa, even though the male’s second-gnathopod resembles that of P. moorei, because this genus lacks a gill on gnathopod 2 while I. camptonyx possesses one. Thurston considered that the few males available for study were juvenile because they all lacked a thumb as in Jassa. However, some of these specimens were larger than the adult, ovigerous females. The female allotype was 4.5 mm and the male holotype was 5.5 mm. This suggests that the male holotype is actually an adult that will not produce a thumb, in which case it is not Jassa. Therefore, until the range of variation can be assessed in Thurston’s specimens, this species should remain in Ischyrocerus with a question as to its proper generic placement. Uncertain status of Ischyrocerus anguipes in the Southern Hemisphere. Sars’ (1894) excellent illustrations of I. anguipes may have resulted in some mis-identifications by early workers in the Southern Hemisphere. Alternatively, their identifications were correct and I. anguipes was being introduced by shipping if the specimens came from ports. K. H. Barnard’s (1916) “ I. anguipes ” could have been a species of Neoischyrocerus, however, as the specimens were 3 mm and the male’s second gnathopod propodus was 3.5 x longer than wide with the dactyl nearly the full length of the propodus, which is typical of adult male Neoischyrocerus. Schellenberg’s (1953) “ I. anguipes ” from L ̹ deritzbucht, Namibia was a 4.8 mm male which he stated differed from K. H. Barnard’s (1916) “ I. anguipes ” in its gnathopod 2 morphology. “ The metacarpus of the 2 nd gnathopod is shaped in the same way but stronger and exhibits a spination like on the first gnathopod. The palm is evenly finely corrugated (or: “ wavy ”) along its almost entire length. ” (Der fast gleich geformte, aber stärkere Metacarpus des 2. Gnathopoden zeigt die Bestachelung wie am 1. Gnathopoden. Die Palma ist fast in ihrer ganzen Länge gleichmässig fein gewellt.) (translated from German to English by Jan Beermann, Alfred Wegener Institute, Bremerhaven, Germany). The similarly shaped gnathopods 1 and 2 suggest that this specimen was a female or juvenile, or an adult male of a different species, as adult male I. anguipes have a gnathopod 2 that is more than twice the length of gnathopod 1, with a concave, rather than convex palm. Schellenberg illustrated the uropod 3 outer ramus as 5 - cusped, terminating in a basally immersed, dorsally recurved spine similar to Jassa. The corona of spines at the peduncle’s distal margin is typical of Ischyrocerus and Jassa. “ I. anguipes ” captured off the coast of Ceylon in ~ 150 m depth were briefly described by Walker (1904) but not illustrated. One male and one ovigerous female were 2.5 mm long. The male’s gnathopod 2 was similar to that of I. anguipes, but this could also be Neoischyrocerus which has similarly shaped, though more pendulous second gnathopods with the dactyl in the largest males nearly the full length of the propodus. Chilton (1921) described “ I anguipes ” from Lyttelton, New Zealand which were up to 6 mm long, saying that they closely resembled Sars’ (1894) illustrations of that species. His description was minimal, however, and he provided no illustrations.	en	Conlan, Kathleen E. (2021): New genera for species of Jassa Leach (Crustacea: Amphipoda) and their relationship to a revised Ischyrocerini. Zootaxa 4921 (1): 1-72, DOI: 10.11646/zootaxa.4921.1.1
