Carinosquilla mclaughlinae, Ahyong, 2006

Ahyong, Shane T., 2006, A new species of Carinosquilla (Crustacea, Stomatopoda, Squillidae) from the Seychelles with a cladistic analysis of the genus, Zoosystema 28 (2), pp. 307-314 : 308-311

Carinosquilla mclaughlinae n. sp. ( Figs 1 ; 2 )

Carinosquilla carinata – Moosa & Cleva 1984: 427, 428 [part]. — Moosa 1991: 194-196 [part]. Non Serène 1954.

TYPE MATERIAL. — Seychelles. Holotype: REVES 2 , stn 36, 4°40.7’S, 55°03.0’E, 62- 55 m, sand, trawl, 10.IX.1980, ♂ TL 71 mm (MNHN-Sto 896).

Paratypes: REVES 2, stn 22, 5°16.3’S, 55°58.2’E, 60 m, sand and shell, dredge, 6.IX.1980, 1 ♀ TL 77 mm (MNHN-Sto 894). — REVES 2, stn 42, 4°31.6’S, 56°09.7’E, 55-60 m, sand and shell, trawl, 13.IX.1980, 1 ♀ TL 83 mm (MNHN-Sto 897).

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ETYMOLOGY. — This species is named in honour of Pat McLaughlin for her longstanding contributions to carcinology.

DISTRIBUTION. — Known only from the Seychelles at depths of 55- 62 m.

MEASUREMENTS. — Male (n = 1) TL 71 mm, female (n = 2) TL 77-83 mm. Other measurements of holotype: CL 15.61 mm, anterior carapace width 7.48 mm, cornea width 4.10 mm, antennular peduncle length 16.48 mm, antennal scale length 11.10 mm.

DIAGNOSIS. — Eyestalk with irregular dorsal carinae. Ocular scales with apices entire. Raptorial claw merus with vermiform sculpture on outer margin; dactylus with six or seven teeth. Dorsolateral carinae of AS 6 and telson divided, forming field of spines.

DESCRIPTION

Eyestalk with short, irregular dorsal carinae; CI 380-409. Ocular scales entire, apices truncate, not bifurcate.

Antennular peduncle 1.02-1.06 CL. Antennular somite dorsal processes with acute, triangular apices; directed anterolaterally. Antennal scale length 0.65-0.72 CL.

Rostral plate trapezoid, about as long as broad; apex truncate to rounded; lateral margins carinate; with long, distinct, median carina flanked by longitudinal supplementary carina (interrupted distally in male specimen).

Carapace anterior width 0.47-0.50 CL; anterior bifurcation of median carina opening anterior to dorsal pit; dorsum covered with numerous closely spaced longitudinal carinae; anterolateral spines reaching anteriorly approximately to level of base of rostral plate.

Raptorial claw dactylus with six or seven teeth; outer surface of propodus with short oblique carina and longitudinal carina subparallel to occlusal margin; carpus with undivided dorsal carina; outer surface of merus with vermiform sculpture.

Mandibular palp 3-segmented. Maxillipeds 1-4 each with epipod.

TS5 lateral process bilobed; anterior lobe a slen- der spine directed anterolaterally; posterior lobe short, slender, directed laterally.TS6 lateral process bilobed; anterior lobe broad, quadrate, apex truncate; posterior lobe broad, triangular. TS7 lateral process bilobed; anterior lobe triangular, blunt; posterior lobe larger than anterior lobe, broad, triangular, anterior margin convex, apex blunt. TS8 with sharp, triangular, lateral process; sternal keel rounded.

TS5 dorsal carinae longitudinal or oblique, none transverse; supplementary carinae between submedian carinae posteriorly spined. TS6-8 and AS 1-5 with most or all supplementary dorsal carinae posteriorly armed above level of lateral carinae. AS 1- 5 with one to three (usually two) supplementary carinae armed between lateral and marginal carinae. Surface of AS 1-5 between intermediate and lateral carinae with some shorter carinae also spined. Articular membrane between AS 5 and 6 lined with small spines. AS 5 with three or four spinules on posterior margin between submedian and lateral carinae. AS 6 submedian carina tricarinate, usually with median spine on posterior margin between submedian spines; with three to six spinules on posterior margin lateral to submedian spines; with short dorsal carinae usually posteriorly spined; sternum with anterior and posterior transverse carina, median carina flanked by four or five sinuous transverse carinae, some uniting laterally; with small ventrolateral spine anterior to uropodal articulation. Abdominal somites with normal complement of carinae spined as follows: submedian 1-6, intermediate 1-6, lateral 1-6, marginal 1-5.

Telson about as long as broad; prelateral lobe longer than margin of lateral tooth, terminating in sharp spine; dorsolateral surface with numerous supplementary longitudinal carinae; proximal supplementary carinae subdivided and posteriorly spined forming field of spines; denticles submedian 4, intermediate 7 or 8, lateral 1; ventral surface with long postanal carina, numerous long supplementary carinae and several short carina and tubercles proximomedially.

Uropodal protopod with smooth outer margin; inner margin with 10-13 slender spines; with short ventral tubercle anterior to endopod articulation; protopod terminal spines with lobe on outer margin of inner spine rounded, narrower than adjacent spine, proximal margin slightly concave. Exopod proximal segment outer margin with 10 or 11 movable spines, distalmost not exceeding mid-length of distal segment; distal margin 2 ventral spines, outer longest. Exopod distal segment slightly longer than proximal segment; unpigmented; dorsally and ventrally carinate. Endopod dorsally and ventrally carinate.

Colour in alcohol

Faded to pale brown. Carinae of carapace dark brown. Posterior margins of thoracic and abdominal somites dark brown. AS 2 with dark transverse bar across submedian carinae. AS 5 with diffuse pigmentation dorsally between intermediate carinae, and with large black patch below intermediate carinae. Telson with apices of primary teeth and apex of median carina dark brown. Uropodal protopod dark at articulation with exopod; distal half of endopod dark; exopod unpigmented except on articular membrane separating distal and proximal segments.

REMARKS

Carinosquilla mclaughlinae n. sp. is unique in the genus in having the supplementary carinae of AS 6 and proximomedial supplementary carinae of the telson broken into short posteriorly spined carinae forming a field of spines. In bearing carinate ocular peduncles and entire, non-bifurcate ocular scales, Carinosquilla mclaughlinae n. sp. resembles C. thailandensis , C. australiensis and C. balicasag . Carinosquilla mclaughlinae n. sp. further resembles C. thailandensis in the vermiform sculpture on the outer surface of the merus of the raptorial claw, but differs by having six or seven instead of five teeth on the dactylus of the claw, and in having the posterior spines of the supplementary abdominal carinae that continue below the level of the intermediate carinae. In having six or seven teeth on the dactylus of the raptorial claw and spined supplementary carinae between the abdominal intermediate and lateral carinae, C. mclaughlinae n. sp. resembles C. australiensis and C. balicasag . Carinosquilla mclaughlinae n. sp., however, differs from C. australiensis and C. balicasag in having vermiform sculpture on the outer surface of the merus of the claw, and in having armed supplementary abdominal carinae not only between the intermediate and lateral carinae, but also between the lateral and marginal carinae. It further differs from both C. australiensis , C. balicasag and C. thailandensis in having many of the supplementary carinae on the lateral surfaces of the abdomen broken into several short posteriorly spined carinae, in having the prelateral lobe of the telson terminating in a sharp spine, in having a carinate outer margin of the propodus of the claw, and in colour pattern. In C. mclaughlinae n. sp., a black patch is present laterally on AS 5 (absent in C. australiensis and C. thailandensis ) and the segments of the uropodal exopod appear to be unpigmented (entirely or partially dark in other species).

The three specimens of the type series are morphologically uniform but vary in the following features: 1) the male bears seven teeth on the dactylus of the raptorial claw, whereas the two females bear six dactylar teeth; and 2) the carina lateral to the median carina of the rostral plate is interrupted distally in the male, whereas the carina is entire in the two females. These differences are likely to represent individual variation instead of sexual dimorphism. Variation in the number of dactylar teeth on the raptorial claw is present also in C. redacta , and similar variation in the development of the rostral plate carinae is occasionally evident in all species of Carinosquilla .

Figures

FIG. 1. — Carinosquilla mclaughlinae n. sp., ♂ holotype (TL 71 mm) (MNHN-Sto 896), Seychelles: A, anterior; B, dorsal process of antennular somite, right lateral view; C, posteromedian portion of carapace; D, right raptorial claw; E, TS5, right lateral view; F, TS5- 8, right dorsal view; G, TS sternal keel, right lateral view; H, AS1, right lateral view; I, posterior abdomen, telson and uropod; J, AS6 and telson, ventral view; K, right uropod, ventral; L, pleopod 1 endopod, left anterior view. Abbreviations: AS, abdominal somite; TS, thoracic somite. Scale bar: A-K, 4 mm; L, 2 mm.

FIG. 2. — Phylogeny of Carinosquilla Manning,1968,strict consensus of five most parsimonious topologies (length 50, consistency index 0.73, retention index 0.83).Jackknife proportions indicated on branches. Characters are listed in Appendix 1; data matrix is presented in Appendix 2. Abbreviations: L., Lophosquilla; Q., Quollastria.