Achaeus umu, Boyko, 2016
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publication ID |
https://doi.org/10.1590/2358-2936e2016019 |
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persistent identifier |
https://treatment.plazi.org/id/F979EC25-FF9D-FFAB-FBEE-FE83A336B5D5 |
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treatment provided by |
Felipe |
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scientific name |
Achaeus umu |
| status |
sp. nov. |
Achaeus umu View in CoL n. sp.
( Figs. 1–3 View Figure 1 View Figure 2 View Figure 3 )
Type material. Holotype female (1.9 × 2.7 mm) ( USNM 1253231 About USNM ), Motu Iti, 158 feet (= 48.2 m), coll. H. Tonnemacher, 28 August 1999.
Etymology. This species is named in memory of our friend, Prof. Dr. Michael Türkay (1948–2015) to honour his great love of gastronomy. Umu , memorably experienced first-hand by the second author during his visit in 1999, is a traditional and delicious Easter Island meal consisting of a mixture of meat, fish, vegetables and fruit wrapped in banana leaves and roasted in an earth oven ( umu pae).
Diagnosis. Carapace short, anterior part not elongated; pseudorostrum short, lobes rounded, smooth, with broad V-shaped hiatus; submedian granule present on supraorbital eave; gastric, cardiac and branchial regions with 4, 2 and 6 tubercles, respectively; very short postorbital region not prominently constricted, hepatic lobe broad, triangular; ocular peduncle with large anterodistal lobe; basal antennal article with 1 low tubercle; ischium of third maxilliped with 2 longitudinal rows of spinules and merus with 1 large basal tubercle; P2 longest, dactylus very long, almost straight with curved distal part, unarmed; P4 and P5 dactylus semilunate, ventral margin lined with 5–7 sharp teeth.
Description of female holotype. Carapace short, maximum length 1.4 times maximum carapace width ( Figs. 1A View Figure 1 , 2A View Figure 2 ). Dorsal surface with 14 rounded granules or tubercles, otherwise smooth; gastric, branchial and cardiac regions clearly demarcated by broad grooves; surface and margins with long and short straight, plumose and curved setae which do not obscure surface ( Figs. 1A View Figure 1 , 2A View Figure 2 ). Pseudorostrum short, bilobed, each lobe triangular with rounded tip, separated by distinct broad V-shaped hiatus ( Figs. 1A View Figure 1 , 2A, B View Figure 2 ). Supraorbital eave wide, outer margin gently convex, edges rounded, surface with 1 low, submedian granule ( Fig. 2A View Figure 2 ). Eye relatively short, stout; ocular peduncle with prominent projection on anterodistal edge just before cornea peduncle; cornea large, round, positioned obliquely backwards from peduncle ( Figs. 1A, B View Figure 1 , 2A, B View Figure 2 ). Postorbital region between supraorbital eave and hepatic region very short, not prominently constricted ( Figs. 1A View Figure 1 , 2A View Figure 2 ). Hepatic region distinctly inflated, triangular in dorsal view, with 1 large tubercle and small, low granule on anterior margin; separated from branchial region by wide concavity ( Fig. 2A View Figure 2 ). Pterygostomian region with 1 prominent, anteriorly directed tubercle midway along margin, visible in dorsal view behind hepatic region; 1 smaller tubercle posterior to it, 1 small granule posterior to this, not clearly visible in dorsal view ( Fig. 2A, B View Figure 2 ). Gastric regions gently convex; epigastric region prominent, unarmed; protogastric region with 1 submedian rounded tubercle; mesogastric region with 1 small median rounded tubercle, positioned anterior to 2 protogastric tubercles; metagastric region with 1 large median rounded tubercle ( Figs. 1A View Figure 1 , 2A View Figure 2 ). Cardiac region raised, with 2 small median rounded tubercles positioned side by side; intestinal region gently raised, unarmed ( Fig. 2A View Figure 2 ). Branchial regions swollen, laterally with 3 prominent submarginal tubercles, posteriormost one largest ( Fig. 2A View Figure 2 ). Posterior carapace margin gently concave ( Fig. 2A View Figure 2 ). Antennular fossae large, longitudinally ovate; basal article unarmed ( Figs. 1B View Figure 1 , 2B View Figure 2 ). Interantennular septum (proepistome) narrow, compressed, not projecting outwards ( Fig. 2B View Figure 2 ). Basal antennal article completely fused with epistome, almost smooth, with 1 low submedian tubercle; article 3 short, quadrate, article 4 elongate; flagellum long, about half carapace length ( Figs. 1A View Figure 1 , 2A, B View Figure 2 ). Epistome wider than long, with small tubercle just anterior of and lateral to green gland opening; posterior margin gently sinuous ( Figs. 1B View Figure 1 , 2B View Figure 2 ). Buccal cavity wide, with anterolateral edge rounded, reaching beyond edge of epistome ( Figs. 1B View Figure 1 , 2B View Figure 2 ).
Third maxilliped elongate; ischium longitudinally subovate, submedian sulcus distinct, w ith sublongitudinal row of 3 spinules on each side, mesial margin uneven, with small pits and granules; merus subtriangular, posterior margin with prominent median tubercle; carpus, propodus and dactylus unarmed; exopod long, smooth, reaching to beyond distal edge of merus ( Fig. 2C View Figure 2 ).
Chelipeds slender, relatively long ( Fig. 1C View Figure 1 ). Ischium subtrigonal, inner margin with low lamelliform ridge with subdentate margin; merus trigonal in cross-section, with 2 large subterminal tubercles on anterodistal part and 2 low sharp granules on dorsal margin; ventral margin uneven, margins with long straight and curved setae ( Fig. 1C View Figure 1 ). Carpus with tubercles on dorsal margin; small granules ventrally; surface with curved setae ( Figs. 1C View Figure 1 , 3G View Figure 3 ). Chela with palm slightly longer than wide; surface smooth; fingers as long as palm, relatively stout; pollex almost straight, dactylus gently curved; cutting margins with low teeth ( Figs. 1C View Figure 1 , 3G View Figure 3 ).
Ambulatory legs very long, slender; surface covered with long and short straight, curved and plumose setae; P2 longest, remaining legs decreasing regularly in length, fourth shortest ( Fig. 3A–F View Figure 3 ); margins of merus uneven but not distinctly armed; P2 dactylus long, almost straight except for curved distal part, unarmed ( Fig. 3A, D View Figure 3 ); P3 dactylus gently curved, distal half of ventral margin with 5 denticles, distalmost one largest ( Fig. 3E View Figure 3 ); P4 dactylus prominently curved, semilunate, distal half of ventral margin with 5 sharp teeth, distalmost one largest ( Fig. 3B View Figure 3 ); P5 positioned subdorsally, leg arching over dorsal surface of carapace; dactylus prominently curved, semilunate, distal half of ventral margin with 7 sharp teeth, distalmost one largest ( Figs. 1A View Figure 1 , 3C, F View Figure 3 ).
Abdomen relatively wide, all somites and telson free ( Fig.2D View Figure 2 ); median surface of all somites with prominent large median tubercle, appearing subtruncate on somites 5 and 6; median part of telson with low tubercle ( Fig. 2D View Figure 2 ); somite 1 trapezoidal, reaching coxae of last pair of ambulatory legs ( Figs. 1B View Figure 1 , 2A, D View Figure 2 ); somite 2 longer than somite 1, subtrapezoidal, lateral margins gently concave; somite 3 with lateral margins distinctly convex; somites 4–6 rectangular, lateral margins sinuous; telson subtriangular, broad, lateral margin convex along anterior part, becoming gently concave posteriorly with tip rounded ( Fig. 2D View Figure 2 ); pleopods finger-like ( Fig. 1B View Figure 1 ).
Thoracic sternum with surfaces smooth; sternites 1 and 2 fused, sloping inwards towards buccal cavity, separated from sternite 3 by convex ridge; sternites 3 and 4 completely fused, surface gently concave ( Fig. 1B View Figure 1 ). Vulva small, round, on submedian part of sternite 6.
Remarks. With regards to the short and rounded pseudorostrum, broad and prominent hepatic lobe and structure of the last ambulatory legs, A. umu n. sp. most resembles the Indo-West Pacific Achaeus lacertosus Stimpson, 1858 . The latter species, however, has a smooth carapace without any tubercles (cf. Sakai, 1976: text fig.82), unlike that of A. umu n. sp. ( Figs. 1A View Figure 1 , 2A View Figure 2 ). Achaeus umu n. sp. is also similar to Achaeus spinosus Miers, 1879 (Persian Gulf to Japan) but the postorbital region of the new species is short (vs. postorbital region distinctly longer in A. spinosus ), the hepatic region has only one small granule in addition to the lobe (vs. the hepatic region with two or more granules in addition to the lobe in A. spinosus ) and the branchial region only has three tubercles (vs. the lobe and the branchial region only has one tubercle in A. spinosus ) (cf. Sakai, 1976: text fig. 85).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.