taxonID	type	description	language	source
77650E13FFED3624FC45FAB04B4572B2.taxon	diagnosis	Diagnosis Oncaeidae. Body cyclopiform, prosome elongate. P 2 - bearing somite without dorsoposterior projection in female. Cephalosome without lateral lobate extensions. P 5 - bearing somite with 2 or 3 paired midventral spinous processes. Genital double-somite in female oval or oval-elongate, not swollen dorsally; with several transverse spinule rows ventrally. First and second postgenital somites shorter than anal somite. Posterior margins of urosomites with lobate or undulate hyaline frill. Anal somite with wide anal opening; vestigial operculum with minute spinules. Exoskeleton moderately chitinized. Sexual dimorphism in antennule segmentation and armature, maxilliped, genital segmentation and ornamentation, and P 6; slight modifications also in P 5, sometimes in caudal rami and in number of midventral spinous processes on P 5 - bearing somite. Antennule 6 - segmented in female, with armature formula 1 - [3], 2 - [8], 3 - [5], 4 - [2 + ae], 5 - [2 (ae absent or not discernible)], 6 - [5 + (1 + ae)]; 4 - segmented in male, with formula 1 - [3], 2 - [8], 3 - [4], 4 - [9 + 2 ae + (1 + ae)]. Distalmost seta of female segment 3 absent in male. Proximal aesthetascs short and delicate, aesthetasc on segment 5 not discernible in female, possibly absent. Spinular row along inner nonsetiferous margin of segment 2 and 3 (absent in S. humesi). Antenna prehensile. Enp- 1 without projection on outer margin; inner margin with denticular row. Enp- 2 about as long as enp- 1; posterior surface with single row of spinules; lateral armature consisting of 2 bare setae (seta IV absent) and 1 long spiniform seta with strong spinules (III); distal armature consisting of 4 strong setae (A – D), ornamented with spinules bilaterally at distal part and unilaterally in some cases along entire length, and 3 bare setae (E – G) of varying length, seta G very short, all elements shorter in length than setae A – D. Labrum distinctly bilobate. Lobes with 3 – 4 marginal teeth apically flanked by row of small spinules. Median concavity membranous, with anterior patch of overlapping spinules. Posterior face with group of 3 – 4 large pores near apical margin of each lobe; with 2 sclerotized teeth medially. Anterior face without paired integumental pockets or slit-like pores; spinular row (s) present. Mandible with 2 blades and 2 or 3 setae. Seta A as long as blade B. [Blades fused basally along posterior surface; dorsal concavity of B cupping ventral basal process of C.] Blade C spinulose along entire dorsal margin. Seta D spiniform and very short (S. ivlevi) or absent (S. humesi sp. nov., S. tenuis sp. nov.). Seta E longest, spiniform and multipinnate. Maxillule weakly bilobate, with 6 elements: inner lobe (= praecoxal arthrite) with 3 elements, innermost one not distinctly displaced, outermost element spiniform and bearing 2 rows of spinules; outer lobe with 3 elements, setiform and sparsely pinnate or naked, innermost element absent. Maxilla with allobasis equal in length to syncoxa. Maxilliped ♀ ovoid-elongate. Basis without ornamentation on posterior surface; anterior surface with double row of strong, spatulated setules along palmar margin and additional spinular row increasing in length distally; both palmar elements spiniform, proximal one about half the length of distal one, bipinnate (ivlevi) or bare, distal one bipinnate. Enp- 1 completely separated. Enp- 2 with long, pinnate claw, rudimentary outer setule, and fused unipinnate inner spine. Maxilliped ♂. Palmar margin forming shallow longitudinal cleft bordered by anterior fringe of short blunt setules, developed into small distal flap, and posterior 2 or 3 rows of coarse, blunt spinules. Anterior surface of basis with short spinular row near distal seta (ivlevi) or unornamented. Distal palmar seta long and bipinnate, proximal seta absent. Endopodal claw curved, pinnate, without hyaline apex. Swimming leg armature formula given in Table 2 (interspecific differences in exopodal spine count marked in bold). Intercoxal sclerite of P 1 sometimes ornamented with paired row of long, fine spinules. Outer basal seta very long in P 4, sometimes exceeding length of exopod. P 1 exopod. Outer and terminal spines with subapical tubular extension, which is lacking on exp- 2 and on proximalmost spine of exp- 3; lateral spines on exp- 3 slightly increasing in size distally. P 1 endopod. Enp- 1 with inner seta sometimes spiniform and reduced in length. Enp- 2 with few, long spinules along inner margin. Enp- 3 outer spine stout, with narrow serrate hyaline flanges; base of distal inner seta concealed beneath long anterior spinous outgrowth of segment. P 2 - P 4 exopods. Outer spines stout, with broad serrate hyaline flanges; lateral spines on P 2 exp- 3 (not on P 3 – P 4) slightly increasing in size distally. P 2 - P 4 endopods 3 - segmented. Enp- 1 with inner seta short and spiniform, with strong spinules, particularly in P 4. Enp- 2 of P 4 with both inner setae reduced in length, proximal one much shorter than distal one. Enp- 3 longer than enp- 1 and - 2 combined; without conical processes. Enp- 3 inner distal spine slightly increasing in length from P 2 – P 4, with moderately narrow serrate hyaline flanges; outer distal and outer spines small, serrate hyaline flanges very narrow or sometimes even absent (P 4). P 5 represented by very long outer basal seta and small exopod delimited from somite; exopodal seta long and setiform, naked or sparsely plumose. Sexual dimorphism in length of exopodal seta. Genital apertures of ♀ large, located at about midregion of dorsal surface of genital double-somite; each operculum with small spinule, which is hardly discernible. Male P 6 membranous flaps produced posterolaterally into spinous process; without armature. Caudal ramus about two to three times as long as wide; variation in length to width ratio within and between geographical regions; without conspicuous dorsal expansion surrounding base of seta VII. Seta I absent; setae II small, spiniform and naked or with 2 spinules; element III a modified strong spine, sometimes ornamented with few spinules along medial margin, base of spine concealed by extended posterolateral margin of CR; setae IV less than 3 times longer than seta III, indistinctly dilated; seta V with anterior half distinctly dilated and naked, posterior part with short pinnules, seta VI short, sometimes bipinnate, not fused basally to seta V; seta VII long and naked or sparsely plumose. No seta displaced. Etymology The generic name is derived from the Latin spina, meaning spine, and refers to the spiniform posterolateral seta (III) on the caudal ramus. Gender: feminine. Type species: Oncaea ivlevi Shmeleva, 1966 = Spinoncaea ivlevi (Shmeleva, 1966) comb. nov. Other species: Spinoncaea humesi sp. nov. Spinoncaea tenuis sp. nov. Phylogenetic relationships The new genus Spinoncaea is closely related to O. tregoubovi Shmeleva, 1968, Monothula subtilis (Giesbrecht, 1892), and Oncaea curvata Giesbrecht, 1902, which together were found to form a robust clade within the family Oncaeidae (Böttger-Schnack & Huys, 2001: figure 6). Oncaea prendeli Shmeleva, 1966, which had not been available for the earlier phylogenetic studies, was assigned to this clade upon recent examination of specimens from the type locality in the Adriatic Sea. The Red Sea species Oncaea sp. K, which was erroneously named ‘ prendeli ’ in the earlier phylogenetic study by Böttger-Schnack & Huys (1998), will be described as a new species, Spinoncaea tenuis, in the present account. In the discussion, Böttger-Schnack & Huys (2001) pointed to the discrepancies in topology of the clade as compared to the preliminary consensus tree presented by Böttger-Schnack & Huys (1998), which were attributed to refinement of the data set by recent examination of the small species and the addition of characters which had previously been ignored or neglected. The monophyly of the revised clade was supported by the following characters: (1) the prehensile antenna in which the distal endopodal segment is elongate and slender, typically articulating with the proximal endopodal segment by means of a narrow base, and being distinctly longer than this segment; (2) the reduction of element IV on the antenna; (3) the secondarily enlarged proximal palmar seta on the male maxilliped, being much longer than the distal seta, whereas in all other oncaeids both setae are about equally long or the distal seta is markedly longer than the proximal seta; (4) the presence of a spinular row along the inner margin of P 1 enp- 2; this row is somewhat reduced in S. ivlevi and S. tenuis sp. nov., but still represented by a few long spinules, whereas in other Oncaeidae the margin of this segment is naked. The first character, a prehensile antenna, has evolved independently in other oncaeid lineages such as Conaea and Epicalymma, but this was regarded as the product of convergence by Böttger-Schnack & Huys (2001). The last two characters appear to be unique for the clade. All species of the clade show a close resemblance in labral structure, particularly the presence of 2 medial teeth on the posterior face of the concavity. The ornamentation of the labrum has proven to be of great importance in unravelling phylogenetic relationships within the Oncaeidae (Böttger-Schnack & Huys, 1998). Two lineages were defined within the clade by Böttger-Schnack & Huys (2001): the tregoubovi – ivlevi - group lineage and the subtilis – curvata lineage. O. tregoubovi and the ivlevi - group cluster together on the basis of the following synapomorphies: (1) the presence of midventral spinous processes on the P 5 - bearing somite; (2) the reduction of the P 5 exopod, being represented by a small free segment but retaining only 1 seta (and 1 spinule); and (3) the dilated caudal rami setae IV and (particularly) V. Within this clade, O. tregoubovi occupies the most primitive position. The monophyly of the ivlevi - group was substantiated by two synapomorphies: (1) hyaline frill of urosomites undulate or lobate; and (2) modification of caudal ramus seta III into a very strong spiniform element. Further differences between O. tregoubovi and the ivlevi - group found during the present study include (1) antennary seta IV being absent in ivlevi - group (small in tregoubovi), (2) maxillule with 6 elements (7 in tregoubovi), (3) distal palmar seta on male maxilliped absent (small in tregoubovi) and (4) the relatively short caudal seta IV (long in tregoubovi). Based on these morphological findings and supported by strong indications from our faunistic studies that the two taxa represent species complexes, both O. tregoubovi and the ivlevi - group are now attributed to generic rank. Oncaea prendeli, which had not been available for study during the earlier phylogenetic analyses, was recently re-examined based on material from the Adriatic Sea and is tentatively assigned to the tregoubovi - lineage of oncaeids. A detailed redescription of O. tregoubovi and O. prendeli is in progress, which will also include a summary of morphological characters separating the two species from Spinoncaea (R. Böttger-Schnack & R. Huys, in prep.). The sister-group of O. tregoubovi and the ivlevi - group, the subtilis – curvata clade, is supported by: (1) the fusion of the P 5 exopod to the supporting somite (but retaining its full complement of setae), and (2) the secondarily enlarged postgenital somites in the female, which are as long as or even longer than the anal somite. A further synapomorphy of this clade mentioned by Böttger-Schnack & Huys (2001) is the presence of marginal teeth apically on each lobe of the labrum, however, this character was found to be shared by the ivlevi - group upon recent reexamination. Spinoncaea species differ in exopodal spine count on swimming leg 2, showing 2 spines (S. humesi) or the typical number of 3 spines (S. ivlevi and S. tenuis) on the distal segment. In other oncaeid genera, usually the swimming leg armature is uniform for all species (e. g. Triconia, Oncaea s. str.); however, differences in the exopodal spine count on leg 2 were also observed in a recently described new Red Sea species belonging to the zernovi - group (Böttger-Schnack, 2002), indicating that this phenomenon might be more widespread in oncaeids than previously known.	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFE93636FF46F8B34C33737A.taxon	description	Other descriptions Shmeleva (1969): 5 – 8, 27, Fig. 3 a – i (♀), Fig. 4 a – h (♂); Malt (1982): 186 – 187, 193, Fig. 3 a – k (♀), 4 a – d (♂)	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFE93636FF46F8B34C33737A.taxon	materials_examined	Type locality Southern Adriatic Sea, Stn. 46: 40 ∞ 40.8 ¢ N, 18 ∞ 50 ¢ E; Stn: 47: 40 ∞ 57.6 ¢ N, 18 ∞ 48.3 ¢ E; 0 – 500 m. Material examined See Table 3 (a).	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFE93636FF46F8B34C33737A.taxon	discussion	Preliminary note In the following, the typical, ‘ robust’ form of S. ivlevi from the Red Sea main basin is described in detail. Morphological differences of a more elongate female form variant occurring in the southern Red Sea will be given below under ‘ Variability ’. The taxonomic identity of the 2 forms will be discussed by detailed comparison with specimens of S. ivlevi (Shmeleva) from the type locality in the Adriatic Sea, comparing and discussing also the taxonomic status of specimens from various other geographical locations.	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFE93636FF46F8B34C33737A.taxon	description	Description of female Body length (measured in lateral aspect; from anterior margin of rostral area to posterior margin of caudal rami, calculated as sum of individual somites): 400 Mm [traditional method: 338 Mm, range: 330 – 340 Mm, based on 5 specimens from the Red Sea]. Exoskeleton well chitinized. Prosome 2.4 times length of urosome, excluding caudal rami, 2.0 times urosome length including caudal rami. P 2 - bearing somite without dorso-posterior projection in lateral aspect (Fig. 2 B). Integumental pores on prosome as indicated in Fig. 2 (A, B). Pleural areas of P 4 - bearing somite with rounded posterolateral corners. Proportional lengths (%) of urosomites are 8.8: 54.2: 8.8: 9.5: 18.7. Proportional lengths (%) of urosomites and caudal rami are 7.4: 46.0: 7.4: 8.1: 15.9: 15.2. P 5 - bearing somite with 2 paired midventral spinous processes (Fig. 2 E). Posterior margin of genital double-somite and postgenital somites with lobate hyaline frill (Fig. 2 C, D). Genital double-somite 1.8 times as long as maximum width (measured in dorsal aspect) and 1.4 times as long as postgenital somites combined; variation in length to width ratio as shown in Table 4; lateral margins rounded, largest width measured at halfway the distance between anterior and posterior margin, posterior part tapering slightly. Pore pattern and ornamentation on dorsal surface as in Figure 2 (C); ventral surface with numerous rows of minute spinules (Fig. 2 E). Paired genital apertures located dorsally at about 2 / 5 distance from anterior margin of genital double-somite; armature represented by 1 diminutive spinule (Fig. 2 J). Anal somite about as wide as long; slightly shorter than CR (measured along outer margin), or about as long as CR (measured along inner margin) (Fig. 2 C), variation in length to width ratio as shown in Table 4. Paired dorsal sensillae anterior to anal operculum not found. Two pairs of secretory pores present dorsally near posterior margin. Anterior margin of anal opening (vestigial anal opening) with minute spinules. Posterior margin of somite finely serrate ventrally and laterally (Fig. 2 C, D). Caudal ramus (Fig. 2 F) 1.8 times longer than wide measured along inner margin and 2.3 times longer than wide measured along outer margin; variation in length to width ratio as shown in Table 4. Armature consisting of 6 elements (for numbering of elements cf. Fig. 12 F): seta II small, spiniform, and unornamented; seta III very strong, spiniform and ornamented with few minute spinules along medial margin, base of seta laterally concealed by serrate margin of CR (Fig. 2 D, F); seta IV less than 1.5 times as long as seta III, bipinnate; seta V longest, lanceolate, naked at anterior half, with short pinnules bilaterally at posterior half; this seta easily gets lost during handling; seta VI short, about as long as seta III, bipinnate; seta VII long, about 2 / 3 length of seta V, bipinnate and biarticulate at base. Inner margin of CR with row of setules. Dorsal anterior surface (Fig. 2 F) with secretory pore near insertion of seta II. Antennule 6 - segmented (Fig. 2 G), weakly chitinized, relative lengths (%) of segments measured along posterior nonsetiferous margin 13.2: 12.7: 40.4: 13.2: 6.6: 13.9. Armature formula: 1 - [3], 2 - [8], 3 - [5], 4 - [2 + ae], 5 - [2 (ae not discernible)], 6 - [5 + (1 + ae)]. Aesthetasc on segment 4 very slender, aesthetasc on segment 5 not discernible, possibly absent [but see male, Fig. 5 (G)]; apical aesthetasc well developed and fused basally to adjacent seta. Segments 2 and 3 ornamented with short pinnules along nonsetiferous margin. Antenna 3 - segmented, distinctly reflexed (Fig. 3 A). Coxobasis with row of long spinules along outer margin and few spinules of varying length along inner margin; with very long seta at inner distal corner, ornamented with strong spinules of decreasing length bilaterally. Endopod segments about equal in length; proximal endopod segment elongate-oval, expanded outer margin bearing spinular row (s) and 1 strong spine; posterior surface with row of short, strong denticles along inner margin; 2 strong denticles on anterior surface. Distal endopod segment about 3 times longer than wide, with narrow cylindrical base articulating with the proximal endopod segment; posterior surface with row of short spinules along outer margin; lateral armature consisting of 2 bare setae, with seta II shorter than seta I, and 1 long spiniform seta (III), ornamented with strong spinules bilaterally at distal half and unilaterally at proximal part, seta IV absent; distal armature consisting of 4 long spiniform setae (A – D), ornamented with spinules bilaterally at distal part and sometimes unilaterally along entire length (A), 3 naked setae (E – G) of varying length, posterior seta (G) extremely small. Labrum (Fig. 3 B, C) distinctly bilobed. Distal (ventral) margin of each lobe with 3 marginal teeth medially, differing slightly in size, long row of small spinules at outer ventral margin and row of small spinules or denticles along inner margin. Median concavity covered anteriorly by overlapping rows of fine spinules. Anterior surface (Fig. 3 B) with paired row of long setules; median swelling weakly developed, with large secretory pore proximally. Posterior wall of medial concavity with two chitinized spinous teeth, flanked by row of minute denticles or spinules (Fig. 3 C). Posterior face with 4 secretory pores located distally on lobe. Mandible (Fig. 3 D) gnathobase with 5 elements: 3 setae and 2 blades. Ventral element (A) as long as ventral blade (B), with long, fine setules along dorsal side; ventral blade strong and spiniform, unornamented; dorsal blade (C) strong and broad, spinulose along entire dorsal margin; dorsal elements (D, E) setiform and bipinnate, element D very short and inserting near base of seta E, difficult to discern in some specimens. Maxillule (Fig. 3 E) indistinctly bilobed, surface ornamentation not discernible. Inner lobe (praecoxal arthrite) with 3 elements: outermost element spiniform, swollen at base, ornamented with row of spinules and 1 coarse spinule, tip with tubular extension; middle element setiform and bare; innermost element smallest located along concave inner margin close to other elements, swollen at base and ornamented with 2 spinules. Outer lobe with 3 elements [innermost element absent]; outermost element curved and bare, similar in length to the following; element next innermost with long spinules unilaterally; innermost seta longest and bare. Maxilla (Fig. 3 F) 2 - segmented, allobasis nearly as long as syncoxa. Syncoxa unarmed, surface ornamented with 1 large secretory pore. Allobasis produced distally into slightly curved claw bearing 2 small spinules on outer margin and 2 rows of strong spinules along medial margin; spinules of inner row shorter, proximal group of 3 spinules on outer row longer, small gap between proximal and distal group; outer margin with strong seta extending to tip of allobasal claw, ornamented with long spinules bilaterally at distal part; inner margin with slender naked seta and strong basally swollen spine with double row of long spinules along the medial margin and few spinules along outer margin (Fig. 3 F). Maxilliped (Fig. 3 G) 4 - segmented, comprised of syncoxa, basis and 2 - segmented endopod. Syncoxa unarmed, surface ornamentation not discerned. Basis elongate, palmar margin with 2 spiniform bipinnate elements, proximal element about half the length of distal one; fringe of short spatulated spinules between proximal seta and articulation with endopod; anterior surface with row of broad spatulated pinnules and short spinules of varying length along palmar margin as illustrated in Fig. 3 (G). Proximal endopod segment unarmed. Distal endopod segment drawn out into long curved claw, with pinnules along entire concave margin; accessory armature consisting of minute, naked seta on outer proximal margin and unipectinate spine fused basally to inner proximal corner of claw. Swimming legs 1 – 4 biramous (Fig. 4 A – D), with 3 - segmented rami. Spine and setae formula as shown in Table 5. Intercoxal sclerites well developed, without ornamentation. Coxae and bases with sparse surface ornamentation as figured. Bases with plumose (P 1) or naked (P 2 – P 4) outer seta, arising from posterior surface, longest in P 4; inner portion of basis slightly produced adaxially into rounded (P 1) or pointed (P 2 – P 3) process, bearing short spinule (s) along inner margin in P 1 – P 2 (Fig. 4 A, B), pointed process smallest in P 4. Inner basal seta on P 1 spiniform and naked. Respective legs without distinct length differences between exopod and endopod. Bases of spines on exopodal and endopodal segments anteriorly surrounded by small spinules, hardly discernible in P 2 – P 4. Surface ornamentation of all segments sparse. Exopods. Outer margin of exopod segments with well developed serrated hyaline lamella; inner margin of proximal exopod segments with long setules. Secretory pore present on posterior surface of distal segments, also present on anterior surface of P 2. Hyaline lamellae on outer spines well developed; outer and terminal spines of P 1 with subapical tubular extension, except for spine on exp- 2 and proximalmost spine on exp- 3. Spine on middle segment and proximal spine on distal segment of P 2 reduced in length. Terminal spine equal in length to (P 1) or shorter than (P 2 – P 4) distal exopod segment. Endopods. Outer margin of endopod segments with fringe of long setules, except for first endopod segment of P 4. Inner seta of proximal endopod segment short, slightly swollen and ornamented with spinules bilaterally (P 1 – P 3) or spiniform with strong spinules bilaterally (P 4). Inner setae of P 4 reduced in length, in particular setae on middle segment, with proximal seta reaching little further than insertion of distal seta and distal seta reaching only half length of seta on distal segment. Distal endopod segments with large secretory pore in P 1 and P 4, located on anterior surface (P 1) or on posterior surface (P 4). Inner margin of P 1 enp- 2 ornamented with 2 long spinules (arrowed in Fig. 4 A). Distal margin of P 1 enp- 1 - and - 2 ornamented with row of denticles or spinules on anterior face; outer margin of enpd- 3 terminating in long process obscuring insertion of distalmost inner seta, process ornamented with short spinule. Distal margin of P 2 – P 3 not produced into conical process, but apical pore of reduced process present, located laterally between subdistal and distal spine (Fig. 4 B, C). Outer subdistal spine on P 3 equal in length to outer distal spine, reaching as far as insertion of this spine. Inner setae of distal endopod segments in P 2 – 4 with spinule comb along proximal inner margin; this comb less obvious in P 1; also present on distal inner seta of middle endopod segment in P 2 – P 4. P 5 (Fig. 2 I, H) comprised of long, naked seta arising from lateral surface of somite, and small free segment representing exopod. Exopod 1.6 times longer than wide, bearing single long, bare seta; posterior margin ornamented with small spinule ventrally (Fig. 2 I) and small spinous process dorsally (Fig. 2 H). P 6 (Fig. 2 J) represented by operculum closing off each genital aperture; armed with a short spinule, variable in conspicuousness (e. g. not discerned in specimen from Monterey Bay, cf. Fig. 7 A). Egg-sacs paired (Fig. 2 K), each sac containing 2 large eggs (diameter 40 – 50 Mm). Description of male Body length: 369 Mm [traditional method: 313 Mm, range: 310 – 320 Mm, based on 3 specimens from the Red Sea]. Pore pattern as in Fig. 5 (A). Sexual dimorphism in antennule, maxilliped, P 6, and in genital segmentation, slight modification in setal length of P 5. Proportional lengths (%) of urosomites (excluding caudal rami) 9.2: 61.3: 4.0: 4.0: 4.8: 16.7; proportional lengths (%) of urosomites (caudal rami included) 7.9: 52.6: 3.4: 3.4: 4.1: 14.3: 14.3. Posterior margin of leg 5 - bearing somite with paired row of 2 or 3 midventral spinous processes (Fig. 5 E). Caudal rami 1.9 times longer than wide measured along inner margin and 2.5 times longer than wide measured along outer margin, similar to female. Caudal setae with proportional lengths as in female. Dorsal surface of genital somite covered with minute denticles or spinules, arranged in a specific pattern (Fig. 5 D) and a paired posterolateral pore. Surface of genital flaps and ventral surface of anal segment ornamented with several rows of strong denticles or spinules and a paired posterolateral pore (Fig. 5 E, F). Ventral surface of caudal ramus with secretory pore near posterior margin (Fig. 5 E). Antennule (Fig. 5 G) 4 - segmented; distal segment corresponding to fused segments 4 – 6 of female; relative lengths (%) of segments measured along posterior nonsetiferous margin 9.0: 19.3: 40.7: 31.0. Armature formula: 1 - [3], 2 - [8], 3 - [4], 4 - [9 + 2 ae + (1 + ae)], aesthetascs very small and slender, small middle aesthetasc close to seta, which is not discernible in the female, shown separately in Fig. 5 (G), apical aesthetasc fused basally to adjacent seta. Antenna as in female. Maxilliped (Fig. 5 B, C) 3 - segmented, comprising syncoxa, basis and 1 - segmented endopod. Syncoxa with single secretory pore at inner distal margin, unarmed. Basis elongate, moderately inflated in proximal half, forming small bulbous swelling; anterior surface with row of short spinules along palmar margin, developed into small distal flap (Fig. 5 B), short row of spinules proximally; posterior surface with 2 – 3 rows of short spatulated spinules of graduated length along palmar margin (Fig. 5 B, C); with 1 long setae within the longitudinal cleft, ornamented with strong spinules bilaterally, corresponding to distal seta in female, proximal seta absent (Fig. 5 B). Endopod drawn out into long curved claw, concave margin ornamented with pinnules along entire concave margin as in female; accessory armature consisting of short, unipectinate spine basally fused to inner proximal corner of claw; tip of claw without hyaline apex. P 1 – P 4 with armature as in female; length of inner setae on middle segment of P 4 as in robust form of female. P 5 (Fig. 5 E, F) exopod with general shape and armature as in female; exopodal seta and long seta arising from lateral surface of somite somewhat shorter than in female. P 6 (Fig. 5 E) represented by posterolateral flap closing off genital aperture on either side; covered by pattern of strong denticles as shown in Fig. 5 (E); posterolateral corners protruding laterally so that they are well discernible in dorsal aspect (Fig. 5 D). Spermatophore oval (Fig. 5 E), of variable size according to state of maturity; swelling of spermatophore during development not affecting shape and relative size of genital somite.	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFE93636FF46F8B34C33737A.taxon	materials_examined	alcohol	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFE93636FF46F8B34C33737A.taxon	discussion	Remarks Taxonomy. Shmeleva (1966) described both sexes of Oncaea ivlevi from the southern Adriatic Sea and figured the female habitus, antennule, antenna, maxilliped and swimming legs, as well as the dorsal aspect of the male. Later, she published a French version of the original Russian description by including material from the equatorial Atlantic and provided figures of the habitus, antenna, maxilliped and swimming legs for both sexes as well as the female antennule (Shmeleva, 1969). The setal count of female P 3 differed between the 2 publications: the correct number of 2 setae is figured in the original description (1966: fig. 1.8), whereas only 1 seta was figured in the subsequent account (1969: fig. 3 h). In both descriptions the inner seta on the distal endopod segment of P 4 is lacking in the female (1966: fig. 1.9; 1969: fig. 3 i), whereas in the male P 4, the presence of this seta might be deduced from the insertion figured (fig. 4 h). The inner seta on P 4 can easily be overlooked, because it is located on the posterior surface of the segment (cf. Figs 3 D and 5 C, G). Shmeleva figured the basis of P 2 with a long spine at the adaxially produced inner margin (1966: fig. 1.7; 1969: fig. 3 g), which was not confirmed during the present study and is not found in any other oncaeid species known to date. Several other elements are incomplete or missing in Shmeleva’s figures, such as the number of elements on the caudal ramus in both sexes, the lateral and distal armature of the antenna and the armature of the antennule. Also, the level of detail required for taxonomic descriptions of oncaeids is not met by her figures (e. g. the ornamentation of the proximal basal seta and the distal endopod segment (claw) on the maxilliped are missing). Shmeleva erroneously described the exopod of P 5 as having 2 setae (1966: p. 933), not just one, and did not mention the seta on the P 5 - bearing somite near the leg; it might be possible that she mixed up the two elements by mistake. In the male, the sexually dimorphic antennule and the lack of the proximal basal element on the maxilliped was not noted by Shmeleva (1966, 1969). Her description of sexually dimorphic distal endopod spines in P 3 and P 4, being shorter in the male (1969: fig. 4 g, h), was not confirmed upon re-examination of specimens from the Adriatic and / or the Red Sea. Despite the differences between Shmeleva’s description and the present account, specimens from the Red Sea were regarded as conspecific with O. ivlevi on the basis of (1) the leg armature and (2) the possession of a very strong spinous seta III on the caudal ramus. The second character is also found in the closely related Spinoncaea humesi sp. nov., but differences in the leg armature clearly separate the two species (see below). The identification of Red Sea S. ivlevi was furthermore supported by comparison with specimens from the Adriatic Sea, which appeared to be conspecific. Differences between specimens from the two areas are summarized and discussed below under ‘ Variability’. Spinoncaea ivlevi is closely related to S. tenuis sp. nov. and S. humesi sp. nov., which are described in the present account. It differs from its congeners by the number of elements on the mandible, showing the full complement of 5 elements (with seta D small in size), whereas a reduced number of 4 elements (seta D absent) is found in S. tenuis and S. humesi. From S. tenuis it can be furthermore separated by (1) the proportional lengths of the urosomites, (2) the much stronger spine (III) on the CR, (3) the different form of seta IV, which is setiform and not dilated as in S. tenuis and (4) the length of seta V, which is much shorter than in S. tenuis. Another difference was found in the ornamentation of the inner margin of P 4 enp- 2, showing the typical fringe of long setules in S. ivlevi, as compared to only one long spinule in S. tenuis. However, the consistency of this character needs to be confirmed by further studies. S. ivlevi and S. humesi can be separated most easily by the different spine count on the distal endopod segment of P 2, showing 3 spines in S. ivlevi, but only 2 spines in S. humesi. The two species also differ in (1) the form of the genital doublesomite, which is barrel-shaped in S. humesi, (2) the proportions of the distal endopod segment of the antenna, (3) the length of basal seta on P 4 and (4) the length of the seta near P 5, representing the outer basal seta of the incorporated protopod of leg 5. Further differences between the two species, including details of ornamentation, are described below under ‘ Remarks’ of S. humesi. Variability. Two form variants of female Spinoncaea ivlevi were found in the Red Sea, a robust form as described above and an elongate form, which differed in the length to width ratio of the genital doublesomite, the anal somite and the caudal ramus: generally, the elongate form showed higher ratios than the robust form (Table 4). The elongate form differed from the robust form in the following characters: (1) total body length smaller than robust form, measuring 388 Mm [traditional method: 310 Mm, based on 2 specimens from southern Red Sea]; (2) exoskeleton less chitinized than robust form; (3) prosome 2.2 times length of urosome, excluding caudal rami, 1.8 times urosome length including caudal rami (Fig. 6 A); (4) proportional lengths (%) of urosomites and caudal rami are 7.3: 46.1: 7.0: 7.3: 15.7: 16.4 (Fig. 6 B); (5) P 5 - bearing somite with number of midventral spinous processes differing between left (2 processes) and right (3 processes) side of specimen examined (Fig. 6 B); (6) genital double-somite more elongate than in robust form, 1.9 times as long as maximum width (measured in dorsal aspect) and 1.5 times as long as postgenital somites combined, lateral margins rounded in anterior half, largest width measured at 4 / 5 the distance between anterior and posterior margin, posterior part tapering gradually (Fig. 6 B); (7) anal somite 1.3 times longer than wide; about as long as CR (measured along outer margin) or distinctly longer than CR (measured along inner margin) (Fig. 6 B); (8) caudal ramus about twice as long as wide measured along inner margin and 2.5 times longer than wide measured along outer margin; armature and ornamentation as in robust form, except for seta II ornamented with a single long spinule (Fig. 6 B) – seta V lacking in all Red Sea specimens examined; and (9) reduced inner setae on P 4 enp- 2 shorter than in robust form, with proximal seta hardly reaching insertion of distal seta and distal seta reaching little further than insertion of inner seta on distal segment (Fig. 6 C). Antennule, antenna, and mouthparts of the Red Sea elongate form were not examined in detail. Males of S. ivlevi in the Red Sea could not be separated into the 2 forms during the present study, because they did not exhibit morphological differences in general habitus corresponding to the two female forms, and microscopical examination of undissected specimens gave no clear evidence of differences in the setal length on P 4 enp- 2 (see above under no. 9). Thus, the observed morphological differences of the females were not regarded sufficient to warrant a separation of the two forms into different species and they are regarded as conspecific in the present paper. The reference material of female S. ivlevi from the type locality in the Adriatic Sea corresponded to the elongate form from the Red Sea in all morphological characters described above (Fig. 6 D – G, Table 4). Antennule, antenna, and mouthparts of the Adriatic specimens were examined in detail and proved to be similar in morphology to the typical ‘ robust’ form from the Red Sea. The single male specimen available from the Adriatic Sea was similar in dorsal aspect (Fig. 7 B) and size [310 Mm, traditional method] to specimens from the Red Sea, with minor differences in the length of exopodal seta on P 5, being somewhat shorter, and the proportional lengths of caudal setae, with seta IV being slightly longer than in Red Sea specimens. The proportional lengths of endopodal seta on P 4 could not be clearly investigated on the single specimen available, which was undissected. At present, it cannot be decided, which one of the 2 forms of S. ivlevi is conspecific with O. ivlevi sensu Shmeleva, because it is not known whether the robust form of S. ivlevi occurs in the Adriatic Sea as well. If subsequent investigations confirm that only the elongate form occurs in the Adriatic Sea, this form should be identified as the original S. ivlevi and one of the female specimens examined during the present study might then be designated as the neotype (Fig. 6 A, Table 3 (a), ZMH reg. no. K- 40095). If subsequent investigations prove both forms to be found in the type locality, however, it has to be decided by the next reviewer which one of the two forms will be designated as the neotype, as Shmeleva’s original description does not give sufficient information to solve this question. Pending the solution of this problem both forms are regarded as O. ivlevi sensu lato. In the Red Sea, the two forms of S. ivlevi differed in regional distribution. The robust form was distributed in the entire Red Sea main basin, extending to the northernmost parts and the Gulf of Aqaba (Böttger-Schnack et al., 2001), whereas the elongate form has thus far been found only in the southernmost Red Sea and in the Gulf of Aden. Outside the Red Sea, specimens similar to the ‘ robust’ form of S. ivlevi were recorded from the eastern Mediterranean, the NE Indian Ocean (oceanic and off NW Cape of Australia) as well as in the NW Pacific (Kuroshio extension) and the NE Pacific (Monterey Bay) during the present study (Tables 3 and 4). Specimens close to the ‘ elongate’ form of S. ivlevi were recorded from the Adriatic Sea (see above), from the eastern Mediterranean and from the NE Indian Ocean and the NW Pacific (Tables 3 and 4). The morphological characteristics of the form variants differed somewhat between geographical regions, thus making unequivocal designation to either form difficult. The ‘ robust’ form of S. ivlevi in the eastern Mediterranean, for instance, showed a combination of characters of the two Red Sea forms: the length to width ratio of the anal somite was intermediate between the robust and the elongate form of Red Sea S. ivlevi, whereas the caudal rami of the Mediterranean robust type were more similar to the Red Sea elongate form (Table 4). Despite these morphological differences, the Mediterranean form was called ‘ robust’, in order to differentiate it from a more ‘ elongate’ form of S. ivlevi found in this area, whose main characteristic, i. e. the elongate genital double-somite, was even more pronounced than that of the elongate form in the Red Sea. The length to width ratio of the anal somite of the ‘ elongate’ form from the eastern Mediterranean was intermediate between the two Red Sea forms (Table 4); however, the specimens were assigned to the elongate form based on the shape of the genital double-somite and the reduced setal length on the second endopod segment in P 4. The specimen from Monterey showed a length to width ratio of the anal somite intermediate between the two forms of S. ivlevi from the Red Sea (Table 4). It was classified as a ‘ robust’ form primarily on the basis of the setal length on the second endopod segment of P 4 [which can be examined without dissecting the specimen]. The classification of form variants of S. ivlevi from geographical localities other than the Red Sea and the type locality (Adriatic Sea) during the present study was based on a limited number of morphological characters which can be examined without dissecting the specimens. More detailed taxonomic examinations of S. ivlevi from the world ocean, including the mouthparts and more details of the swimming legs, are needed to clarify the taxonomic status of the various form variants. Future taxonomic investigations should a priori focus on Spinoncaea species from the Adriatic Sea, in order to elucidate the remaining uncertainties in the identification of the species from the type locality of S. ivlevi. Other records of S. ivlevi. A taxonomic record of Spinoncaea ivlevi was given by Malt (1982; as Oncaea ivlevi), who redescribed the species from the NE Atlantic. She noted some morphological differences between her specimens and Shmeleva’s original description, such as the armature of the caudal rami, the ornamentation of maxillipedal elements and the length of the terminal spine on the exopods of swimming legs, all of which were similar to those described for Red Sea specimens in the present paper. The apparent sexual difference in endopodal spine lengths as described by Shmeleva (1969) was not commented upon by Malt (1982). Malt’s redescription of S. ivlevi includes an incomplete figure of the maxilla, but the remaining mouthparts are lacking. In her redescription, the number of elements on the antennule (fig. 3 d) is incomplete and one element is missing on the lateral armature of the antenna (fig. 3 e). In the swimming legs (fig. 3 I – k) she erroneously figured the seta on the first endopod segment in P 1 – P 4 as being long and slender, not swollen and reduced in length as typical for Spinoncaea (in particular in P 4); also, the proximal seta on the second endopod segment in P 4 is as long as the distal seta (fig. 3 k), not short and spiniform. In the male maxilliped, she erroneously reported two short palmar setae (p. 187, fig. 4 d), not one long seta as typically found in the ivlevi-group. The lack of detail of her figures makes it difficult to assign her specimens to one of the two form variants of S. ivlevi. Malt’s statement (p. 187) that the second endopod segments of P 2 – P 4 have ‘ relatively small conical projections’ seems to be erroneous, because it does not match with her figures. Instead, she figured the distal exopod segment of P 4 having a conical projection (fig. 3 k), which is not found in Spinoncaea species. In a comprehensive study on the seasonal and vertical distribution of microcopepods in the Adriatic Sea, Kršinić (1998) reported S. ivlevi as a dominant species in the 50 – 300 m layer. In the zone of its maximum abundance, at 100 – 200 m, the species contributed about 30 % to the total number of oncaeids (F. Kršinić, unpubl. data). Kršinić was not aware of the closely related S. tenuis sp. nov., which was found to co-occur with S. ivlevi in the epipelagic zone of the Adriatic during the present study. Thus, he might have included both species under the name O. ivlevi.	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFE93636FF46F8B34C33737A.taxon	distribution	Geographical distribution. Spinoncaea ivlevi is distributed in the entire Red Sea, including its northernmost extension, the Gulf of Aqaba (Böttger-Schnack et al., 2001). In the Strait of Bab al Mandab, at the southern entrance of the Red Sea, a great number of unidentified copepods of the ivlevi - group had been reported by Böttger-Schnack (1995; as Oncaea ivlevi / K). Re-examination of parts of this material during the present study showed that the samples contained a mixture of S. ivlevi elongate form, S. tenuis and S. humesi. In the adjacent Arabian Sea, living S. ivlevi have not yet been recorded, but a number of empty exoskeletons (carcasses) were found in the central region indicating less favourable environmental conditions for the species during the sampling period (Böttger-Schnack, 1996). Unidentified specimens of the ivlevi - group from the northern Arabian Sea (Böttger-Schnack, 1996; as Oncaea sp. D) were found to consist of S. tenuis and tregoubovi - type specimens upon recent re-examination.	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFE93636FF46F8B34C33737A.taxon	discussion	Vertical distribution and vertical migration. The vertical distribution of S. ivlevi in the Red Sea needs to be re-evaluated, because the species was not separated from the closely related S. humesi during the earlier quantitative studies (Böttger-Schnack, 1988, 1990 a, b, 1995; as Oncaea ivlevi typical form). Generally, the two species combined exhibited an unimodal distribution in the lower epipelagic zone, with maximum abundances at 50 – 100 (200) m and no diurnal vertical migration became apparent (Böttger-Schnack, 1990 a). Females usually were vertically more extended than males. Seasonal and / or regional differences from this distribution pattern during various seasons and in different regions of the Red Sea appeared to be minor (Böttger-Schnack, 1990 b, 1995 and unpubl. data). An evaluation of the species specific distribution pattern of S. ivlevi and S. humesi in the northernmost Red Sea and the Gulf of Aqaba is in progress (R. Böttger-Schnack & W. Hagen, in prep.).	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFFA363EFEC0FF7B49BB7775.taxon	description	None. Type locality Northernmost Red Sea, 27 ∞ 25.00 ¢ N, 34 ∞ 04.98 ¢ E: Stn. 156; R / V Meteor leg 44 / 2: collected 4 March 1999 with MSN 0.055 mm net (Haul 9 / 3); depth 300 – 350 m; total water depth 798 m. Material examined See Table 3 (b). Description of female Body length (measured in lateral aspect; from anterior margin of rostral area to posterior margin of caudal rami, calculated as sum of individual somites): 381 Mm [traditional method: 310 – 320 Mm, based on several specimens]. Exoskeleton well chitinized. Prosome 2.0 times length of urosome, excluding caudal rami, 1.7 times urosome length including caudal rami. P 2 - bearing somite without dorso-posterior projection in lateral aspect (Fig. 8 B). Integumental pores on prosome as indicated in Fig. 8 (A, B). Pleural areas of P 4 - bearing somite with rounded posterolateral corners. Proportional lengths (%) of urosomites are 8.3: 51.7: 10.3: 9.5: 20.2. Proportional lengths (%) of urosomites and caudal rami are 7.0: 43.5: 8.7: 8.0: 17.1: 15.7. P 5 - bearing somite with 3 paired midventral spinous processes (Fig. 8 E). Genital double-somite elongate barrel-shaped, 1.9 times as long as maximum width (measured in dorsal aspect) and 1.3 times as long as postgenital somites combined. Pore pattern and ornamentation on dorsal surface as in Fig. 8 (C); ventral surface with numerous rows of minute spinules (Fig. 8 E). Paired genital apertures located dorsally at about 2 / 5 distance from anterior margin of genital double-somite; armature represented by 1 diminutive spinule (Fig. 8 J). Anal somite 1.2 times longer than wide; slightly shorter than CR (measured along outer margin), or about as long as CR (measured along inner margin) (Fig. 8 C), variation in length to width ratio as shown in Table 7. Two pairs of secretory pores present dorsally near posterior margin. Paired dorsal sensillae anterior to anal operculum not found, possibly absent. Anterior margin of anal opening (vestigial anal opening) with minute spinules. Posterior margin of somite finely serrate ventrally and laterally (Fig. 8 C, D). Caudal ramus (Fig. 8 F) 2.6 times longer than wide measured along inner margin and about 3 times longer than wide measured along outer margin; variation in length to width ratio of CR observed for specimens from the eastern Mediterranean and Indo-Pacific region as indicated in Table 7. Armature consisting of 6 elements (for numbering of elements cf. Fig. 12 F): seta II small, spiniform, and unornamented; seta III very strong, spiniform and ornamented with few minute spinules along medial margin, base of seta laterally concealed by serrate margin of CR (Fig. 8 D, F); seta IV 1.5 times longer than seta III, bipinnate; seta V longest, dilated, naked at anterior half, with long pinnules bilaterally at posterior half [this seta easily gets lost during handling]; seta VI distinctly shorter than seta III, naked; seta VII long, about 2 / 3 length of seta V, plumose at distal part and bi-articulate at base. Inner margin of CR unornamented, posterior margin finely serrate ventrally. Dorsal anterior surface (Fig. 8 F) with secretory pore near insertion of seta II. Antennule 6 - segmented (Fig. 8 G), weakly chitinized, relative lengths (%) of segments measured along posterior nonsetiferous margin 7.5: 13.4: 45.2: 12.4: 7.5: 14.0. Armature formula: 1 - [3], 2 - [8], 3 - [5], 4 - [2 + ae], 5 - [2 (ae not discernible)], 6 - [5 + (1 + ae)]. Aesthetasc on segment 4 small and slender, aesthetasc on segment 5 not discerned [but present in male, arrowed in Fig. 11 (G)]; apical aesthetasc well developed and fused basally to adjacent seta. Segments 2 and 3 without ornamentation along inner, nonsetiferous margin. Antenna 3 - segmented, distinctly reflexed (Fig. 9 A). Coxobasis with row of long spinules along outer margin and few strong spinules along inner margin; with very long seta at inner distal corner, ornamented with spinules bilaterally and 1 long spinule at distal part. Endopod segments unequal in length; proximal endopod segment elongate-oval, slightly expanded outer margin bearing short spinular row and 1 strong spine; posterior surface with row of short, strong denticles along inner margin; ornamentation on anterior surface not discerned. Distal endopod segment slightly longer than proximal segment, about 4 times longer than wide, with narrow cylindrical base articulating with the proximal endopod segment; posterior surface with long row of short spinules along outer margin; lateral armature consisting of 2 bare setae, with seta II slightly longer than seta I [for numbering of elements cf. Fig. 3 (A)], and 1 long spiniform seta (III), ornamented with strong spinules bilaterally at distal half and unilaterally at proximal part, seta IV absent; distal armature consisting of 4 long spiniform setae (A – D), ornamented with spinules unilaterally along entire length (A) or at distal part (C, D), 2 naked setae (E, F) of similar length and 1 very small posterior seta (G). Labrum (Fig. 9 B, C) distinctly bilobed. Distal (ventral) margin of each lobe with 4 marginal teeth medially, differing slightly in size, long row of small spinules at outer ventral margin and row of small spinules or denticles along inner margin. Median concavity covered anteriorly by overlapping rows of fine spinules. Anterior surface (Fig. 9 B) with 2 paired rows of long setules; median swelling weakly developed, with large secretory pore proximally. Posterior wall of medial concavity with two chitinized spinous teeth, flanked by row of minute denticles or spinules (Fig. 9 C). Posterior face with 3 secretory pores located distally on lobe. Mandible (Fig. 9 D) gnathobase with 4 elements: 2 setae and 2 blades (for numbers of elements cf. Fig. 3 D). Ventral element (A) as long as ventral blade (B), with long, fine setules along dorsal side; ventral blade strong and spiniform, unornamented; dorsal blade (C) strong and broad, spinulose along entire dorsal margin; small dorsal seta D absent; dorsal element (E) setiform and bipinnate. Maxillule (Fig. 9 E) indistinctly bilobed, surface ornamentation not discernible. Inner lobe (praecoxal arthrite) with 3 elements: outermost element spiniform, swollen at base, ornamented with row of spinules along 1 side and several spinules on the other side, tip with tubular extension; middle element setiform and bare; innermost element smallest located along concave inner margin close to other elements, swollen at base and ornamented with 1 (or 2?) spinules. Outer lobe with 3 setiform elements [innermost element absent], which are curved and bare, innermost seta longest. Maxilla (Fig. 9 F) 2 - segmented, allobasis nearly as long as syncoxa. Syncoxa unarmed, surface ornamented with 1 large secretory pore. Allobasis produced distally into slightly curved claw bearing 2 small spinules on outer margin and 2 rows of strong spinules along medial margin; spinules of inner row shorter than those on outer row; outer margin with strong seta almost extending to tip of allobasal claw, ornamented with long spinules bilaterally at distal part; inner margin with slender naked seta and strong basally swollen spine with double row of long spinules along the medial margin and few spinules along outer margin (Fig. 9 F). Maxilliped (Fig. 9 G) 4 - segmented, comprised of syncoxa, basis and 2 - segmented endopod. Syncoxa unarmed, surface ornamentation not discerned. Basis elongate, palmar margin with 2 spiniform elements unequal in length; proximal element unornamented and about half the length of distal one, which is bipinnate; fringe of short spatulated spinules between proximal seta and articulation with endopod; anterior surface with row of broad spatulated pinnules and short row of spinules of varying length along palmar margin as illustrated in Fig. 9 (G). Proximal endopod segment unarmed. Distal endopod segment drawn out into long curved claw, with pinnules along almost entire concave margin; accessory armature consisting of small, naked seta on outer proximal margin and unipectinate spine fused basally to inner proximal corner of claw. Swimming legs 1 – 4 biramous (Fig. 10 A – D), with 3 - segmented rami. Armature similar to S. ivlevi, except for spine count on distal exopod segment of P 2, showing 2 outer spines (Table 6). Intercoxal sclerites well developed, without ornamentation. Coxae and bases with sparse surface ornamentation as figured. Bases with plumose (P 1 + P 3) or naked (P 2 + P 4) outer seta, arising from posterior surface, seta very long in P 4, extending almost to tip of distal endopod spine; inner portion of basis slightly produced adaxially into rounded (P 1) or pointed (P 2 – P 4) process, which decreases in size from P 2 – P 4; inner margin of basis ornamented with short spinule (s) in P 1 – P 2 (Fig. 10 A, B). Inner basal seta on P 1 spiniform and naked. Respective legs without distinct length differences between exopod and endopod. Bases of spines on exopodal and endopodal segments anteriorly surrounded by small spinules, hardly discernible in P 2 – P 4. Surface ornamentation of all segments sparse. Exopods. Outer margin of exopod segments with well developed serrated hyaline lamella; inner margin of proximal exopod segments with long setules, not discerned in P 4. Secretory pore present on posterior surface of distal segments, also present on anterior surface of P 2. Hyaline lamellae on outer spines well developed; outer and terminal spines of P 1 with subapical tubular extension, except for spine on exp- 2 and proximalmost spine on exp- 3, which are also reduced in length. Spine on second segment of P 2 reduced in length. Terminal spine slightly longer (P 1) or shorter (P 2 – P 4) than distal exopod segment. Endopods. Outer margin of endopod segments with fringe of long setules. Inner seta of proximal endopod segment short, slightly swollen and ornamented with strong spinules bilaterally, reduced in length and spiniform in P 4. Inner setae of P 4 reduced in length, in particular setae on second endopod segment, with proximal seta reaching little further than insertion of distal seta and distal seta reaching only half length of seta on distal segment. Inner margin of P 1 enp- 2 ornamented with 3 long spinules. Distal margin of P 1 enp- 1 - and - 2 ornamented with row of denticles or spinules on anterior face (not figured); outer margin of enp- 3 terminating in long process obscuring insertion of distalmost inner seta. Conical process at distal margin of P 2 – P 3 absent, but apical pore still present, located laterally between subdistal and distal spine (Figs 10 B, C). Outer subdistal spine on P 3 equal in length to outer distal spine, reaching as far as insertion of this spine. Inner setae of distal endopod segments in P 1 – P 4 with spinule comb along proximal inner margin; also present on distal inner seta of middle endopod segment in P 2 – P 4. P 5 (Fig. 8 H, I) comprised of long, naked seta arising from lateral surface of somite, extending to posterior margin of genital double-somite, and small free segment representing exopod. Exopod 1.7 times longer than wide, bearing single long, bare seta, extending beyond posterior margin of genital double-somite; posterior margin ornamented with small spinule dorsally (Fig. 8 I) and small spinous process ventrally (Fig. 8 H). P 6 (Fig. 8 J) represented by operculum closing off each genital aperture; armed with a minute spinule, which is difficult to discern. Egg-sacs not observed, presumably similar to S. ivlevi. Description of male Body length: 367 Mm [traditional method: 290 Mm (range: 280 – 300 Mm, based on 3 specimens]. Pore pattern difficult to discern, possibly as in Fig. 11 (A). Sexual dimorphism in antennule, maxilliped, P 6, and in genital segmentation, slight modification in setal length of P 5. Proportional lengths (%) of urosomites (excluding caudal rami) 6.9: 64.5: 4.1: 4.1: 4.1: 16.3; proportional lengths (%) of urosomites (caudal rami included) 6.0: 55.7: 3.5: 3.5: 3.5: 14.1: 13.7. Posterior margin of leg 5 - bearing somite with 2 paired midventral spinous processes (Fig. 11 E), not 3 as in female; no variation in number of processes observed in either sex. Caudal rami 2.1 times longer than wide measured along inner margin and 2.7 times longer than wide measured along outer margin. Caudal setae with proportional lengths as in female, except for seta IV, which is slightly shorter. Dorsal surface of genital somite unornamented, pore (s) absent or not discernible. Surface of genital flaps ornamented with several rows of small spinules as figured, surface ornamentation and pore pattern on ventral surface of anal segment and CR absent or not discernible (Fig. 11 E, F). Antennule (Fig. 11 G) 4 - segmented; distal segment corresponding to fused segments 4 – 6 of female; relative lengths (%) of segments measured along posterior nonsetiferous margin 8.3: 18.0: 44.9: 28.8. Armature formula: 1 - [3], 2 - [8], 3 - [4], 4 - [9 + 2 ae + (1 + ae)], aesthetascs very small and slender, small middle aesthetasc, which was not discernible in the female, arrowed in Fig. 11 (G), apical aesthetasc fused basally to adjacent seta smaller than in female. Antenna as in female. Maxilliped (Fig. 11 B, C) 3 - segmented, comprising syncoxa, basis and 1 - segmented endopod. Syncoxa unarmed and unornamented. Basis elongate, moderately inflated in proximal half, forming small bulbous swelling; anterior surface with row of short spinules along palmar margin, developed into small distal flap (Fig. 11 B), short row of spinules proximally; posterior surface with 2 – 3 rows of short spatulated spinules of graduated length along palmar margin (Fig. 11 C); with 1 long seta within the longitudinal cleft, ornamented with strong spinules bilaterally, corresponding to distal seta in female, proximal seta absent. Endopod drawn out into long curved claw, concave margin ornamented with pinnules along distal half of concave margin, not along entire length as in female; accessory armature consisting of short, unipectinate spine basally fused to inner proximal corner of claw; tip of claw without hyaline apex. P 1 – P 4 with armature and ornamentation as in female. P 5 (Fig. 11 D, F) exopod with shape and armature as in female; exopodal seta and long seta arising from lateral surface of somite somewhat shorter than in female. P 6 (Fig. 11 E) represented by posterolateral flap closing off genital aperture on either side; covered by pattern of denticles as figured; posterolateral corners protruding laterally so that they are well discernible in dorsal aspect (Fig. 11 A, D). Spermatophore not observed. Etymology The species is named in honor of the late Professor Arthur G. Humes (Ho, 2001), in recognition of his outstanding contribution to the taxonomy of symbiontic and parasitic copepods (Huys & Boxshall, 2001), which also included a study on oncaeids. Remarks Taxonomy. Spinoncaea humesi is closely related to S. ivlevi, with which it has been confounded during earlier ecological studies in the Red Sea (see below). The two species can be separated by the different spine count on the distal exopod segment of P 2, showing 2 outer spines in S. humesi, whereas the typical number of 3 spines is found in S. ivlevi. Other morphological characters separating the females of the two species are (1) the length ratio of prosome: urosome, being smaller in S. humesi than in S. ivlevi; (2) the form of the genital double-somite, being barrel-shaped in S. humesi, but oval-shaped in S. ivlevi; (3) the length ratio of antennary endopod segments, with the distal one being longer than the proximal one in S. humesi, whereas it is about equal in length in S. ivlevi; (4) the length to width ratio of the antennary distal endopod segment, being greater in S. humesi than in S. ivlevi; (5) the armature of the mandible, showing only 4 elements in S. humesi, with seta D absent, whereas the full set of 5 elements is found in S. ivlevi; (6) the basal seta on P 4, being as long as the leg in S. humesi, whereas it is only about half its length in S. ivlevi; (7) the outer basal seta on P 5, which is longer than the genital double-somite in S. humesi, while being only half its length in S. ivlevi. Further minor differences between S. humesi and S. ivlevi are found in the ornamentation of appendages, such as the lack of spinules on the inner nonsetiferous margin of segments 2 and 3 in the antennule, the greater number of setules on the inner margin of P 1 enp- 2, and the different ornamentation of P 5 exopod. From the robust form of S. ivlevi, the new species can also be separated by the length to width ratio of the caudal rami, being much longer in S. humesi (but see below under ‘ Variability’). Males of S. humesi and S. ivlevi differ in the armature of swimming legs and mouthparts as well as in the length of the outer basal seta on P 5 as stated above. Also, the surface ornamentation in S. humesi males seems to be reduced (P 6) or even absent (genital somite). Morphological differences separating S. humesi from S. tenuis are summarized below under ‘ Remarks’ of S. tenuis. Variability. The length to width ratio of the caudal rami of female Spinoncaea humesi varied between different geographical regions (Table 7). In specimens from the SE Indian Ocean (off Australia) and NW Pacific (Kuroshio Extension) this ratio was similar to that of the elongate form of S. ivlevi co-occurring in both areas (cf. Table 3). Thus, differentiation of the two species in Australian waters and the Kuroshio extension requires (microscopical) examination of the leg armature. Ecological notes. Spinoncaea humesi is distributed throughout the Red Sea main basin, where it co-occurs with S. ivlevi in the epipelagic zone (Böttger-Schnack, 1988, 1990 b, 1995; as Oncaea ivlevi). In the Gulf of Aqaba, the northernmost extension of the Red Sea, it was found to be very rare or even absent, thereby emphasizing the isolated position of this area (Böttger-Schnack et al., 2001). The species was also recorded from the eastern Mediterranean in the present account, but has not yet been found in the Adriatic Sea. In samples from the Indo-Pacific region it occurred in the NE Indian Ocean, off Australia, and in the NW Pacific (Kuroshio Extension), but was not recorded from the NE Pacific (Monterey Bay). The absence of the species in the northern Arabian Sea may be due to some seasonal variation in abundance (see under S. ivlevi). More detailed taxonomical investigations of this new Spinoncaea species in the world ocean are necessary to fully elucidate its zoogeographical distribution. Data on the vertical distribution and vertical migration of S. humesi in the Red Sea are not yet available, as the species was not separated from its sibling species, S. ivlevi, during the earlier ecological studies. Generally, the two species exhibited an unimodal distribution in the lower epipelagic zone, at 50 – 100 (200) m (Böttger-Schnack, 1988, 1990 b, 1995). A detailed investigation of the distribution patterns of both species in the northernmost Red Sea is in progress.	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
77650E13FFF33604FECAFC224872755B.taxon	description	None. Type locality Northernmost Red Sea, 27 ∞ 25.00 ¢ N, 34 ∞ 04.98 ¢ E: Stn. 156; R / V Meteor leg 44 / 2: collected 4 March 1999 with MSN 0.055 mm net (Haul 9 / 3); depth 300 – 350 m; total water depth 798 m. Material examined See Table 3 (c). Preliminary note The typical form of S. tenuis occurring in the Red Sea proper is described in detail in the following. Morphological differences of a more elongate female form that was found in the Strait of Bab al Mandab (southern entrance of the Red Sea) and in various other geographical localities will be given below under ‘ Variability ’. Description of female Body length (measured in lateral aspect; from anterior margin of rostral area to posterior margin of caudal rami, calculated as sum of individual somites): 370 Mm [traditional method: 290 Mm (range: 280 – 300 Mm), based on 2 specimens]. Exoskeleton moderately well chitinized. Prosome 2.1 times length of urosome, excluding caudal rami, 1.8 times urosome length including caudal rami. P 2 - bearing somite without dorso-posterior projection in lateral aspect (Fig. 12 B). Integumental pores on prosome as indicated in Fig. 12 (A, B). Pleural areas of P 4 - bearing somite with rounded posterolateral corners. Proportional lengths (%) of urosomites are 8.2: 62.7: 5.9: 5.9: 17.3. Proportional lengths (%) of urosomites and caudal rami are 7.2: 54.6: 5.1: 5.1: 15.0: 13.0. P 5 - bearing somite with 2 paired midventral spinous processes (Fig. 12 I). Genital double-somite oval-elongate, 2.0 times as long as maximum width (measured in dorsal aspect) and 2.1 times as long as postgenital somites combined; lateral margins rounded, largest width measured at about halfway the distance between anterior and posterior margin, posterior part tapering. Pore pattern on dorsal surface as in Fig. 12 (C); ventral surface with several rows of minute spinules as indicated in Fig. 12 (D). Paired genital apertures located dorsally at about half distance from anterior margin of genital double-somite; armature difficult to discern, possibly represented by 1 diminutive spinule (Fig. 12 G). Hyaline frill on posterior margin of genital double-somite and postgenital somites weakly undulate. Anal somite about as wide as long; slightly shorter than CR (measured along outer margin) or slightly longer than CR (measured along inner margin) (Fig. 12 F), variation in length to width ratio not examined. Dorsal surface with two pairs of secretory pores near posterior margin, paired dorsal sensillae anterior to anal opening absent or not discernible. Anterior margin of anal opening (vestigial anal opening) with minute spinules. Posterior margin of somite finely serrate ventrally and laterally (Fig. 12 C, D). Caudal ramus (Fig. 12 F) 1.9 times longer than wide measured along inner margin and 2.3 times longer than wide measured along outer margin; variation in length to width ratio not examined. Armature consisting of 6 elements, numbered by Roman numerals in Fig. 12 (F): seta II small, spiniform, and unornamented; seta III strong, spiniform and unornamented, base of seta concealed by serrate margin of CR (Fig. 12 D, F); seta IV about twice as long as seta III, moderately lanceolate and bipinnate (Fig. 12 C); seta V about 3 times longer than seta IV, lanceolate, naked at anterior half, posterior half with short spinules along inner margin and longer pinnules along outer margin [this seta easily gets lost during handling]; seta VI shorter than seta III, unornamented; seta VII long, about half length of seta V, bipinnate at distal part and bi-articulate at base. Inner margin of CR unornamented. Dorsal anterior surface (Fig. 12 F) with secretory pore near insertion of seta II. Antennule 6 - segmented (Fig. 12 E), relative lengths (%) of segments measured along posterior nonsetiferous margin 8.0: 17.8: 41.7: 14.7: 7.4: 10.4. Armature formula: 1 - [3], 2 - [8], 3 - [5], 4 - [2 + ae], 5 - [2 (ae not discernible)], 6 - [5 + (1 + ae)]. Aesthetasc on segment 4 very slender, no aesthetasc discernible on segment 5 [but see male, Fig. 15 (G)]; apical aesthetasc well developed and fused basally to adjacent seta. Segment 2 and proximal part of segment 3 ornamented with few, short pinnules along inner, nonsetiferous margin. Antenna 3 - segmented, distinctly reflexed (Fig. 13 A). Coxobasis with row of spinules along outer and inner margins and with pattern of denticles on outer (exopodal) margin; with long seta at inner distal corner, ornamented unilaterally with long spinules, subdistal one very long. Endopod segments about equal in length; proximal endopod segment elongate-oval, expanded outer margin bearing short spinular row; posterior surface with row of short, strong denticles along inner margin. Distal endopod segment about 4 times longer than wide, with narrow cylindrical base articulating with the proximal endopod segment; posterior surface with row of short spinules along outer margin; lateral armature consisting of 2 bare setae, with seta II shorter than seta I, and 1 long spiniform seta (III), ornamented with strong spinules bilaterally at distal half and unilaterally at proximal part, seta IV absent; distal armature consisting of 4 long spiniform setae (A – D), ornamented with spinules bilaterally at distal part and unilaterally along entire (A) or half (C, D) length, 3 naked setae (E – G) of varying length, posterior seta (G) reduced to small spinule. Labrum (Fig. 13 B, C) distinctly bilobed. Distal (ventral) margin of each lobe with 3 marginal teeth medially, differing slightly in size, long row of very small spinules at outer ventral margin and row of small spinules or denticles along inner margin. Median concavity covered anteriorly by overlapping rows of fine spinules. Anterior surface (Fig. 13 B) with 2 paired rows of long setules; median swelling weakly developed, with large secretory pore proximally. Posterior wall of medial concavity with two chitinized spinous teeth, flanked by row of minute denticles or spinules (Fig. 13 C). Posterior face with 3 paired secretory pores located distally on each lobe. Mandible (Fig. 13 D) gnathobase with 4 elements: 2 setae and 2 blades, for indication of elements see Fig. 3 (D). Ventral element (A) as long as ventral blade (B), with long, fine setules along dorsal side; ventral blade strong and spiniform, unornamented; dorsal blade (C) strong and broad, spinulose along entire dorsal margin; dorsal element D absent, element E setiform and bipinnate. Maxillule (Fig. 13 E) indistinctly bilobed, surface ornamentation not discernible. Inner lobe (praecoxal arthrite) with 3 elements: outermost element spiniform, swollen at base, ornamented with 2 rows of spinules, tip possibly with tubular extension; middle element setiform and unipinnate; innermost element smallest, located along concave inner margin close to other elements, ornamented with few spinules. Outer lobe with 3 elements [innermost element absent]; outermost element curved and bare, similar in length to the following; element next innermost with short spinules unilaterally; innermost seta longest and unipinnate. Maxilla (Fig. 13 F) 2 - segmented, allobasis nearly as long as syncoxa. Syncoxa unarmed, surface ornamented with 1 large secretory pore. Allobasis produced distally into slightly curved claw bearing 2 rows of strong spinules along medial margin; spinules of inner row shorter, proximal group of 2 spinules on outer row longer, small gap between proximal and distal group; outer margin with strong seta extending to tip of allobasal claw, ornamented with long spinules bilaterally at distal part and 1 long spinule subdistally; inner margin with slender naked seta and strong basally swollen spine with double row of long spinules along the medial margin and few spinules along outer margin (Fig. 13 F). Maxilliped (Fig. 13 G) 4 - segmented, comprised of syncoxa, basis and 2 - segmented endopod. Syncoxa unarmed, surface ornamentation not discerned. Basis elongate, palmar margin with 2 spiniform elements, proximal element bare, about half the length of distal one, which is bipinnate; fringe of short spatulated spinules between proximal seta and articulation with endopod; anterior surface with row of broad spatulated pinnules and short spinules of varying length along palmar margin as illustrated in Fig. 13 (G). Proximal endopod segment unarmed. Distal endopod segment drawn out into long curved claw, with pinnules along entire concave margin; accessory armature consisting of minute, naked seta on outer proximal margin and unipectinate spine fused basally to inner proximal corner of claw. Swimming legs 1 – 4 biramous (Fig. 14 A – D), with 3 - segmented rami. Spine and setae formula as for S. ivlevi. Intercoxal sclerite of P 1 ornamented with paired row of long, fine setules (Fig. 14 A). Coxae and bases with sparse surface ornamentation as figured. Bases with naked outer seta, arising from posterior surface, longest in P 4; inner portion of basis slightly produced adaxially into rounded (P 1) or pointed (P 2 – P 4) process, bearing short spinule (s) along inner margin in P 1 (Fig. 14 A), pointed process reduced in P 4. Inner basal seta on P 1 spiniform and naked. Respective legs without distinct length differences between exopod and endopod. Bases of spines on exopodal and endopodal segments anteriorly surrounded by small spinules, which are hardly discernible. Surface ornamentation of all segments sparse. Exopods. Outer margin of exopod segments with well developed serrated hyaline lamella; inner margin of proximal exopod segments with long setules. Secretory pore present on posterior surface of distal segments in P 2 – P 4, also present on anterior surface of P 2. Hyaline lamellae on outer spines well developed; outer and terminal spines of P 1 with subapical tubular extension, except for spine on exp- 2 and proximalmost spine on exp- 3. Spine on middle segment and proximal spine on distal segment of P 2 – P 3 reduced in length. Terminal spine slightly longer than (P 1) or equal in length to (P 2 – P 4) distal exopod segment. Endopods. Outer margin of endopod segments with fringe of long setules, except for outer margin of P 4 enp- 1 naked and enp- 2 ornamented with 1 or 2 spinule (s), variable within and between specimens examined [additional spinules possibly indicated by insertion on margin (?), stippled in Fig. 14 (D)]. Inner seta of proximal endopod segment short, slightly swollen and ornamented with spinules bilaterally (P 1 - P 3) or spiniform with strong spinules bilaterally (P 4). Inner setae of P 4 enp- 2 and - 3 reduced in length, in particular those on enp- 2, with proximal seta reaching little further than insertion of distal seta and distal seta not reaching half length of seta on distal segment. Distal endopod segments with large secretory pore on anterior face in P 1. Inner margin of P 1 enp- 2 ornamented with 2 – 3 long spinules. Distal margin of P 1 enp- 1 - and - 2 ornamented with row of short denticles or spinules on anterior face; outer margin of P 1 enp- 3 terminating in long process obscuring insertion of distalmost inner seta. Distal margin of P 2 – P 3 not produced into conical process but apical pore of reduced process present, located laterally between subdistal and distal spine (Fig. 14 B, C). Outer subdistal spine on P 3 equal in length to outer distal spine, reaching as far as insertion of this spine. Inner setae of distal endopod segments in P 2 – P 4 with spinule comb along proximal inner margin; this comb not obvious in P 1; also present on distal inner seta of middle endopod segment in P 3 – P 4. P 5 (Fig. 12 H, I) comprised of very long, sparsely plumose seta arising from lateral surface of somite, and small free segment representing exopod. Exopod 1.5 times longer than wide, bearing single long, bare seta; posterior margin ornamented with small spinule dorsally (Fig. 12 I) and small spinous process ventrolaterally (Fig. 12 H). P 6 (Fig. 12 G) represented by operculum closing off each genital aperture; possibly armed with a short spinule as indicated, variable in conspicuousness [not seen in specimens from Adriatic Sea]. Egg-sacs not observed. Description of male Body length: 356 Mm [traditional method: 294 Mm, range: 280 – 300 Mm, based on 10 specimens]. Pore pattern on prosome not fully discerned (Fig. 15 A). Sexual dimorphism in antennule, maxilliped, P 6, and in genital segmentation, slight modification in length of seta on P 5. Proportional lengths (%) of urosomites (excluding caudal rami) 8.5: 65.5: 3.1: 3.6: 3.6: 15.7; proportional lengths (%) of urosomites (caudal rami included) 7.4: 57.1: 2.7: 3.1: 3.1: 13.7: 12.9. Posterior margin of leg 5 - bearing somite with paired row of 3 midventral spinous processes (Fig. 15 E). Genital somite with length to width ratio 1.7: 1. Caudal rami 1.9 times longer than wide measured along inner margin and 2.3 times longer than wide measured along outer margin, similar to female. Caudal setae with proportional lengths as in female, except for seta III being slightly shorter and seta IV being somewhat longer than in female. Dorsal surface of genital somite covered with paired posterolateral pore (Fig. 15 D). Surface of genital flaps ornamented with several rows of strong denticles or spinules; ventral surface of anal segment without ornamentation. Antennule (Fig. 15 G) 4 - segmented; distal segment corresponding to fused segments 4 – 6 of female; relative lengths (%) of segments measured along posterior nonsetiferous margin 9.5: 16.9: 45.9: 27.7. Armature formula: 1 - [3], 2 - [8], 3 - [4], 4 - [9 + 2 ae + (1 + ae)], aesthetascs very small and slender, apical aesthetasc fused basally to adjacent seta, length not fully discerned (stippled in Fig. 15 G). Ornamention on inner margin of segments 2 and 3 as in female (Fig. 15 g). Maxilliped (Fig. 15 B, C) 3 - segmented, comprising syncoxa, basis and 1 - segmented endopod. Syncoxa missing in specimen figured. Basis elongate, moderately inflated in proximal half, forming small bulbous swelling; anterior surface with row of short spinules along palmar margin, developed into small distal flap (Fig. 15 B); posterior surface with 1 – 2 rows of short spatulated spinules of graduated length along palmar margin (Fig. 15 B, C); with 1 long seta within the longitudinal cleft, corresponding to distal seta in female, ornamented with strong spinules bilaterally; proximal seta absent. Endopod drawn out into long curved claw, concave margin ornamented with pinnules along entire concave margin as in female; accessory armature consisting of short, unipectinate spine basally fused to inner proximal corner of claw; tip of claw without hyaline apex. P 1 – P 4 with armature and ornamentation as in female, ornamentation of second endopod segment in P 4 with several spinules along outer margin (as usually found in oncaeids), not only single spinule as in female. P 5 (Fig. 15 D, F) exopod with general shape and armature as in female; exopodal seta and long seta arising from lateral surface of somite shorter than in female. P 6 represented by posterolateral flap closing off genital aperture on either side; covered by pattern of denticles as shown in Fig. 15 (E); posterolateral corners protruding laterally so that they are well discernible in dorsal aspect (Fig. 15 A, D). Spermatophore oval (Fig. 15 D), of variable size according to state of maturity; swelling of spermatophore during development not affecting shape and relative size of genital somite. Etymology The specific name Latin tenuis, meaning slender, refers to the smaller seta III on the caudal ramus and to the general habitus of the species. Remarks Taxonomy. Spinoncaea tenuis differs from S. ivlevi and S. humesi sp. nov. by the different proportions of the urosomites, with the genital double-somite measuring about 2 / 3 of the urosome, whereas it is only about half the length of the urosomites in the 2 other species. Further differences separating S. tenuis from its congeners are the length ratio and form of caudal setae, in particular the more slender spinous element III, the greater length and different form of seta IV, being slightly dilated and 2.5 times longer than seta III, whereas it is not dilated and only about 1.5 times longer than seta III in S. ivlevi and S. humesi, and the greater length of seta V, being 3 times longer than seta IV, whereas it is only about 2 times longer than this seta in the two other species. The form and length of seta IV appears to be a useful tool in separating species of Spinoncaea from closely related species, such as O. tregoubovi and O. prendeli, because it was found to be consistent within all species (including their form variants) described during the present study. From S. humesi the species can be most readily be distinguished by the spine count on the distal exopod segment of P 2, showing 3 spines in S. tenuis, but only 2 spines in S. humesi. S. tenuis and S. ivlevi share the same swimming leg armature, but in addition to the characters given above they can be separated by (1) the number of elements on the mandible (4 in S. tenuis, 5 in S. ivlevi), (2) the ornamentation of the coxobasal seta in the antenna (unilaterally, with 1 long subdistal spinule in S. tenuis, bilaterally in S. ivlevi) and (3) the ornamentation on the anterior surface of the labrum (2 rows of spinules in S. tenuis, one in S. ivlevi). Another slight difference between the two species is found in the ornamentation of the inner margin of P 4 enp- 2, showing the typical fringe of several long setules in S. ivlevi, whereas there are 2 or even only 1 long spinule (s) in S. tenuis. Variability. Female specimens of Spinoncaea tenuis displayed considerable morphological variation both within and between geographical regions. Differences in body morphology observed during the present study included (1) the form of the genital double-somite and (2) the length to width ratio of (a) the genital doublesomite, (b) the anal somite and (c) the caudal rami. Based on these characters, two form variants of S. tenuis were established, a typical form and an elongate form, with the latter generally exhibiting higher ratios (Table 8). The elongate form of S. tenuis from the Adriatic Sea (Fig. 16 A) was examined in more detail and differed from the typical Red Sea form in the following characters: (1) body length: 390 Mm [traditional method: 315 Mm, range: 300 – 330 Mm, based on 6 specimens from the Adriatic Sea]; (2) proportional lengths (%) of urosomites and caudal rami are 7.1: 52.4: 5.6: 5.6: 14.6: 14.6; (3) genital doublesomite more elongate than in typical form (Fig. 16 B), 2.2 times as long as maximum width (measured in dorsal aspect). Genital apertures located somewhat more anterior than in typical form, at 2 / 5 of distance from anterior margin, armature of genital apertures not clearly discernible; (4) anal somite slightly shorter than CR (measured along outer margin) or about as long as CR (measured along inner margin) (Fig. 16 B); (5) caudal ramus (Fig. 16 B) longer than in typical form, 2.4 times or 2.6 times longer than wide measured along inner or outer margin, respectively; armature and ornamentation mainly as in typical form, except for seta VII being slightly longer and ornamentation of seta V as figured (Fig. 16 B); (6) swimming legs with armature and ornamentation as in typical form, except for basal seta on P 4 stronger and much longer, reaching beyond distal exopod spine (Fig. 16 C). Reduced inner setae on P 4 enp- 2 slightly longer than in typical form, with proximal seta almost reaching insertion of distal seta and distal seta reaching half length of seta on distal segment (Fig. 16 C). Ornamentation on inner margin of P 4 enp- 2 similar to typical form, showing only 1 single spinule [insertion of further spinules not present]; (7) P 5 with outer basal seta slightly longer than in typical form (Fig. 16 B), armature of P 6 not discernible, egg-sacs not found. Antennule, antenna and mouthparts similar to typical form. In the male, morphological differences between specimens of the Red Sea and the Adriatic Sea became less obvious and the assessment of an elongate male morph in the Adriatic Sea appears to be questionable. Adriatic specimens of S. tenuis (Fig. 16 D) were similar in size, measuring 340 Mm in body length [traditional method: 296 Mm, range: 290 – 300 Mm, based on 5 specimens from the Adriatic Sea] and showed similar body proportions and urosome segmentation (Fig. 16 D). However, the genital somite of specimens from the Adriatic was slightly longer than in the typical Red Sea form, with a length to width ratio of 1.8: 1, and the caudal rami were longer, being about 3 times longer than wide (2.8 times longer than wide measured along inner margin, 3.0 times longer than wide measured along outer margin, respectively). Proportional lengths of caudal setae were similar to the typical form, except for seta VII, which was slightly longer. Pore patterns on the prosome and the urosome were not fully discerned in males from the Adriatic Sea. The two forms of S. tenuis differed in geographical distribution (Table 8): the typical form of S. tenuis occurred in the entire Red Sea and was also present in the northern Arabian Sea. The elongate form occurred in the Mediterranean Sea and in the NW Pacific (Kuroshio Extension). Specimens from the NE Pacific (Monterey) were tentatively assigned to the elongate form of S. tenuis on the basis of caudal rami characters, but they showed intermediate values between the two forms in the other characters examined (Table 8). The observed morphological differences between the two female forms of S. tenuis – although being geographically separated – were not regarded as sufficient to warrant recognition of the two forms as separate species, and the Red Sea specimens of S. tenuis are regarded as conspecific with those from the Mediterranean. Specimens from the North Pacific are regarded as conspecific as well, but need to be examined in more detail, as their identification in the present study was based on a limited number of characters only. Based on the present preliminary data, a wide geographical distribution of the elongate form (s) of S. tenuis is indicated, whereas the typical form appears to be restricted to the Arabian and Red Sea. Two additional morphs of the tenuis - type were found outside the Red Sea main basin during the present study (cf. Table 3): In the Adriatic Sea, a single female specimen was separated (= Spinoncaea sp. A), which differed in the form of the genital doublesomite, with lateral margins much straighter than in S. tenuis, and in the nature of caudal rami seta IV, being unusually long and dilated (seta V was broken off in the specimen). With regard to the form of the genital double-somite, the species resembled O. tregoubovi, but the ornamentation of the maxillipedal basis (spatulated setules) and the armature of the antenna (seta IV absent) clearly distinguished it from this species and identified it as Spinoncaea. It may probably represent an as yet undescribed new species. In the Strait of Bab al Mandab (southern Red Sea) another morph of S. tenuis was found (Spinoncaea sp. B, Table 3), which was close to the typical form, but differed slightly in the form of the genital double somite, being more rounded, and in the size of caudal seta III, being larger. The specimens resembled the elongate form of S. ivlevi, but differed from this type in the form of caudal rami seta IV, which was dilated (as in S. tenuis), not setiform as in S. ivlevi. A specimen similar to this type was also found in the central northern Arabian Sea, where it had been grouped together with an as yet unidentified species of the tregoubovi - group under Oncaea sp. D in the earlier quantitative studies (Böttger-Schnack, 1996). Another 2 specimens showing intermediate characters were found in the eastern Mediterranean (Table 3), but their potential identity with Spinoncaea sp. B still needs to be examined. Specimens of Spinoncaea sp. B may be regarded as intermediate morphs of S. tenuis and S. ivlevi or they may represent another as yet undescribed species of Spinoncaea. More and detailed taxonomic studies of the tenuis - complex are needed in order to unravel its taxonomic diversity on a global scale, which still is far from being understood. Ecological notes. Spinoncaea tenuis is the species previously reported as Oncaea sp. K in the Red Sea (Böttger-Schnack, 1992, 1995). During the earlier ecological investigations in the Red Sea main basin (Böttger-Schnack, 1988, 1990 a, b) it had not been separated from the very similar O. tregoubovi Shmeleva which co-occurs in the upper mesopelagic zone. In a subsequent re-evaluation of the earlier data, the abundances and vertical distribution patterns of both species were established separately (Böttger-Schnack, 1992). Similar to S. ivlevi and other small oncaeid species, the actual abundance of S. tenuis had been largely underestimated in the earlier ecological studies in the central Red Sea during autumn and winter (e. g. Böttger-Schnack, 1992), because a net of 0.1 mm mesh had been used, which does not even sample the adults quantitatively (Böttger, 1985). Subsequent zooplankton studies in the central Red Sea conducted with a finer net of 0.055 mm mesh size during summer yielded between 3 and 10 times more adults (Böttger-Schnack, 1995). Also, the proportion of males differed considerably between the two surveys: they contributed 40 – 50 % of adult S. tenuis in the 0.055 mm nets (unpubl. data), but only 0 – 5.0 % of the adults in the 0.1 mm nets (Böttger-Schnack, 1992). Besides some potential seasonal variation in abundance and sex ratio, the results pointed out a much more efficient catch of S. tenuis by the smaller mesh nets, in particular with regard to the males, which are somewhat smaller and more slender than the females. Geographical distribution. Spinoncaea tenuis is distributed throughout the Red Sea main basin and in the Gulf of Aden (Böttger-Schnack, 1995; as Oncaea sp. K). It has recently been recorded also from the Gulf of Aqaba, the northernmost extension of the Red Sea (Böttger-Schnack et al., 2001). In the Strait of Bab al Mandab at the southern entrance of the Red Sea, a considerable proportion of the unidentified specimens of the ivlevi - group reported by Böttger-Schnack (1995; as Oncaea ivlevi / sp. K) were assigned to S. tenuis upon recent re-examination. However, the samples also contained the elongate form of S. ivlevi and S. humesi, both of which are very similar in general aspect. Thus, quantitative data can hardly be provided, due to the difficulties in species identification that arise when all three species of Spinoncaea and their form variants co-occur. The present preliminary results pointed to a greater abundance of S. tenuis in the Strait of Bab al Mandab than previously reported by Böttger-Schnack (1995) and the regional differences in number between the South and the North in the Red Sea have to be corrected accordingly. Outside the Red Sea, S. tenuis was recorded from a wide range of localities, including Atlantic as well as Indo-Pacific regions (Table 3). The small mesh net samples from the Equatorial Indian Ocean (Nishida material) examined during the present study contained only few oncaeids similar to S. tenuis, which were not investigated further. In the copepod material from the SE Indian Ocean, near-shore area of the NW Cape of Australia (McKinnon material), S. tenuis was absent, which might indicate an oceanic distribution of the species. Vertical distribution and vertical migration. In the Red Sea, S. tenuis is mainly distributed in the lower epi- and upper mesopelagic zone between 150 and 600 m depth, with maximum abundances in the 200 – 350 m layer (Böttger-Schnack, 1992, 1995, and unpubl. data). It usually exhibits an unimodal distribution in this depth layer, with little regional variation in oceanic sites (unpubl. data from summer 1987). Thus, the species tends to be vertically separated from its two congeners, S. ivlevi and S. humesi. No diurnal vertical shift of the population centre was observed (Böttger-Schnack, 1992; females only). The vertical extension of males usually was narrower than that of the females. In the shallow southern Red Sea and the Strait of Bab al Mandab, female S. tenuis were concentrated in the near-bottom layer, at 150 – 175 m and 150 – 200 m, respectively, during summer. Males showed a greater vertical extension in the shallow southern Red Sea with constant concentrations between 40 and 175 m depth; they were rare in the Strait. However, due to the difficulties in the identification of the species of the ivlevi - group (see above) the distribution pattern in the Strait might not have been fully discerned.	en	Böttger-Schnack, Ruth (2003): Taxonomy of Oncaeidae (Copepoda, Poecilostomatoida) from the Red Sea. V. Three species of Spinoncaea gen. nov. (ivlevi-group), with notes on zoogeographical distribution. Zoological Journal of the Linnean Society 137 (2): 187-226, DOI: 10.1046/j.1096-3642.2003.00056.x, URL: https://academic.oup.com/zoolinnean/article-lookup/doi/10.1046/j.1096-3642.2003.00056.x
