Carpoapseudes varindex, Bamber, 2007

Bamber, Roger N., 2007, Suborders Apseudomorpha Sieg, 1980 and Neotanaidomorpha Sieg, 1980 *, Zootaxa 1599, pp. 13-40 : 25-30

Carpoapseudes varindex n.sp.

Figures 7–9

Material examined. Holotype, female (KMNH IvR 500.156), station XR5, 42º23.83’– 42º22.06’N 145º31.06’– 145º27.70’E, 3145–3265 metres, 4 m ORE beam trawl, 16 September 2001. Paratype: 1 male, cephalon only (KMNH IvR 500.157), same locality .

Diagnosis. Typical Carpoapseudes , rostrum triangular, longer than eyelobe apophyses, with slight proximal shoulders; antennal flagellum of eight segments, antennular main flagellum of 25 to 26 segments, accessory flagellum (male) of nine segments; pereonite 6 without anterolateral spiniform apophyses. Male with auricular expansion on proximo-ventral margin of cheliped propodus, and dactylus with dorsodistal constriction at insertion of setae.

Etymology. From the Latin varus – bent, and index – forefinger (noun in apposition), with reference to the constriction on the dactylus of the cheliped of the male.

Description of female.

Body ( Fig. 7). Dorsoventrally flattened, elongate, holotype 11.3 mm long (anterior tip of cephalon to posterior of pleotelson), seven times as long as wide, narrower posteriorly.

Cephalothorax. Sub-triangular, 0.9 times as long as wide, naked, anterior margin with rostrum, damaged in holotype (see male, below). Eyes absent; eyelobes modified to prominent spine-like apophyses directed antero-laterally.

Pereonites. Pereonite 1 shortest, about one-third as long as cephalothorax, lateral margins uniformly convex. Pereonite 2 one-tenth as long again as pereonite 1 with slight anterolateral spiniform apophyses. Pereonites 3 to 5 with anterolateral spine-like apophyses, and expanded postero-laterally at attachment of coxae. Pereonite 3 1.5 times as long as pereonite 2. Pereonite 4 longest, 1.5 times as long as pereonite 3. Pereonite 5 0.8 times as long as pereonite 4. Pereonite 6 trapezoid, without lateral apophyses, as long as pereonite 2 (all pereonites respectively 3.2, 2.3, 1.4, 0.8, 0.9 and 1.8 times as wide as long). Ventral hyposphenia present on all pereonites.

Pleon. Just longer than pereonites 4 to 6 together, of five free subequal pleonites bearing pleopods. Pleonites 2.4 times as wide as long, laterally bearing spine-like apophyses.

Pleotelson. Long and slender, as long as last four pleonites together, 2.4 times as long as wide.

Antennule ( Fig. 7B). Peduncle 4-articled. Proximal article elongate, about ten times as long as wide. Second article 0.3 times as long as article 1 with distal crown of six setae. Third article just shorter than article 2. Fourth article 0.2 times as long as third article, naked. Main flagellum of 25 segments, articles 21 and 23 bearing single aesthetascs. Accessory flagellum incomplete.

Antenna ( Fig. 7B). Proximal peduncle article without inner process. Article 2 naked, bearing elongate squama eight simple marginal setae. Peduncle article 3 as long as wide. Article 4 as long as article 1 and 1.5 times as long as article 5. Flagellum of eight segments.

Mouthparts not dissected. Small, naked epistome present. Mandibular palp of three articles, proximal article more than twice as long as wide, article 2 twice as long as article 1 with eight inner setae in the distal third, proximal seta longer than remainder, article 3 half length of article 2 with ten inner setae and two longer distal setae.

Cheliped ( Fig. 8A). Basis twice as long as wide, ventrally with fine spine just distal of midpoint and distal tuft of eight setae. Exopodite present, 3-articled, second article naked, distal article with four plumose setae. Merus elongate with dorsal subdistal seta and ventral subdistal group of three longer and two shorter setae. Carpus 1.5 times as long as wide, expanding distally, with five simple setae along ventral margin, dorsodistal blunt apophysis with two adjacent simple setae. Chela slender, fingers longer than palm, ventral margin with four setae; two small setae near articulation of fixed finger; cutting edge of fixed finger with small, rounded proximal apophysis and row of setules and plate-like teeth ( Fig. 8C). Dactylus with sparse marginal setae but no apophyses on cutting edge ( Fig. 8C), shorter than fixed finger.

Pereopod 1 ( Fig. 7B; 8B, D). With pronounced spine-like apophysis on coxa ( Fig. 7, 8D). Basis slender, 6.5 times as long as wide without proximal apophyses or spine. Exopodite present ( Fig. 8D), 3-articled, article 2 naked, article 3 with six distal plumose setae. Ischium with single simple ventrodistal seta. Merus with row of five ventral setae in distal half. Carpus longer than merus, with ventral row of marginal setae and dorsodistal tuft of four setae, longest of these as long as propodus. Propodus ( Fig. 8B) shorter than merus and 3.4 times as long as wide, with nine slender dorsal setae and six ventral slender setae interspersed with five stouter spines. Dactylus short, less than half length of propodus, with mid-dorsal fine seta and four ventral denticulations; unguis short.

Pereopod 2 ( Fig. 8E, F). More slender. Basis eight times as long as wide with one mid-dorsal and two ventrodistal setae. Merus 0.7 times as long as carpus, not widening distally. Carpus elongate, with ventral and dorsomedial rows of marginal setae. Propodus 0.8 times as long as carpus, with row of ventral marginal setae, sparser mid-dorsal marginal setae and dorsodistal tuft of five setae; single small ventrodistal compound spine. Dactylus slender with one mid-dorsal and one ventrodistal fine seta and three proximo-ventral denticulations; unguis slender, pointed, less than half length of dactylus, the two together longer than propodus.

Pereopods 3 to 6 ( Fig. 7B). Similar to pereopod 2, although pereopod 4 with denser tuft of dorsodistal setae on carpus. Pereopods 5 and 6 less setose.

Pleopods ( Fig. 8G). All alike. Basis elongate with four outer and two inner plumose setae. Endopod shorter than exopod with proximal articulation; both rami slender, respectively with 17 and 16 plumose setae. Outer proximal seta on exopod sub-distally with robust setules, distally naked.

Uropods. Missing.

Description of male (only cephalothorax and associated appendages present: Fig. 9).

Carapace. Rostrum triangular, longer than eyelobe apophyses, with slight proximal shoulders.

Antennule main flagellum of 26 segments, most with paired aesthetascs. Accessory flagellum of nine segments.

Antenna with ten-segmented flagellum.

Cheliped showing sexual dimorphism; chela fingers little longer than palm. Propodus with auricular expansion on proximo-ventral margin; fixed finger with two prominent proximal tooth-like apophyses on cutting edge. Dactylus with dorsodistal constriction at insertion of setae ( Fig. 9C).

Remarks. The conformation of the rostrum (in the male), the antennular and antennal flagella and squama, and the pereonite proportions of the present species are all consistent with the description of C. serratispinosus by Lang (1968). His detailed description related to the male; alas the present male lacks a body and all legs. Unlike Lang’s species, however, the rostrum has only slight proximal “shoulders”, and the cheliped does have an “auricular” expansion on the proximo-ventral margin of the cheliped propodus, as described for C. kudinovae by Bãcescu (1981), who states that this feature may be present in other species for which the fully mature male is undescribed; it is also found in C. auritocheles Kudinova-Pasternak, 1975 , and C. simplicirostris ( Norman & Stebbing, 1886) . The present species is neither of these last two, as C. auritocheles has lateral spiniform apophyses on the anterior margin of the branchial chamber, while, uniquely, C. simplicirostris has a long and slender rostral spine, little wider at its base than apically ( Norman & Stebbing 1886, Pl. 18, Fig. ID).

Carpoapseudes varindex n.sp. may be distinguished from C. kudinovae , a species from the northeast Atlantic to which C. varindex appears closest, in the proportions of pereonites 2 and 3, the lack of anterolateral spiniform apophyses on pereonite 6, the fewer segments in the antennal flagellum and antennular accessory flagellum, fewer setae on the antennal squama, the constriction on the dactylus of the male cheliped, the lack of proximal apophysis on the pereopod 1 basis, more setae on the pereopod 1 exopodite, and in particular the length and setation of the pleopod basis.

According to the key of Guṭu (1996), the present species would key out to C. romanae Bãcescu, 1987 , owing to the relatively short antennal flagellum (ten segments), but that species has a quite different truncate, although pointed, rostrum ( Bãcescu 1987, Fig. 5A).