Catoptrus iejima, Fujita, Yoshihisa & Naruse, Tohru, 2011

Fujita, Yoshihisa & Naruse, Tohru, 2011, Catoptrus iejima, a new species of cavernicolous swimming crab (Crustacea: Brachyura: Portunidae) from a submarine cave at Ie Island, Ryukyu Islands, Japan, Zootaxa 2918, pp. 29-38 : 30-37

publication ID	https://doi.org/ 10.5281/zenodo.207593
DOI	https://doi.org/10.5281/zenodo.6191874
persistent identifier	https://treatment.plazi.org/id/03F287C9-4B50-FF8F-FF34-FAE1FE974F93
treatment provided by	Plazi
scientific name	Catoptrus iejima
status	sp. nov.

Treatment

Catoptrus iejima View in CoL , n. sp.

( Figs. 2–7 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 )

Material examined. Holotype, female, 21.8 × 35.6 mm, RUMF-ZC-1317, point “Ohoba No. 1”, Ie Island, Ryukyu Islands, Japan, - 10m, submarine cave, baited with Pacific saury ( Cololabis saira ), coll. Y. Yamada & K. Yunokawa, 15 Jul. 2010.

Comparative material. Atoportunus dolichopus Takeda, 2003: 1 female, 23.9 × 36.0 mm, RUMF-ZC-1318, 1 female, 20.6 × 30.9 mm, ZRC 2011.0014, KUMEJIMA 2009 stn. Diving 38, Hidenchigama, Kume Island, Ryukyu Islands, Japan, submarine limestone cave, - 35–40 m, coll. Y. Fujita, 19 Nov. 2009. Catoptrus nitidus A. Milne- Edwards, 1870: 1 male, 15.6 × 23.9 mm, MNHN B- 4639, Iles Viti; 2 males, 7.8 × 12.1 mm, 6.5 x ca. 10.1 mm (damaged), 1 juvenile, 4.2 x 6.4 mm, MNHN B- 22342, Samoa. Catoptrus rathbunae Serène, 1966 : Holotype, male, 5.0 × 7.0 mm, MNHN B- 5564, Nhatrang, Vietnam, coll. R. Serène, 14 Aug. 1964; paratype, 1 female, 6.0 × 8.5 mm, MNHN B- 5563, same data as holotype.

Diagnosis. Carapace ovoid, longitudinally, transversely convex. Supraorbital margin beaded on convex part, without fissure; infraorbital margin discontinuous. External orbital angle dorso-ventrally flattened, distally rounded, continuous to anterolateral margin. Anterolateral margins with 5 teeth excluding external orbital angle, first and second teeth, third and fourth teeth placed closer to each other, fifth tooth largest; margins between bases of teeth lined with granules, forming ridge-like structure. Eyes small, not completely occupying orbit. Chelipeds slender; anterior margin of merus with 1 subproximal small tooth, 1 subdistal small tooth; palm swollen with no striae or granules; fingers slender, as long as palm, distally hooked, 3–4 long sharp teeth and few small sharp teeth between them. Ambulatory legs slender, long; propodus of P5 with subparallel inner, outer margins, slender; P5 dactylus lanceolate, dactylus narrower than propodus.

Description. Carapace ovoid, longitudinally, transversely convex, dorsal surface smooth, regions poorly defined ( Figs. 2 View FIGURE 2 , 3 View FIGURE 3 A, 4A, B, 5A). Front bilobed, with small median notch, frontal margin straight, lined with 2 parallel rows of granules; supraorbital margin beaded on convex part, without fissure; infraorbital margin discontinuous, inner orbital lobe dorso-ventrally flattened, produced anteriorly, lobe followed laterally by few, small, granules, one relatively large granule, not continuous to external orbital angle ( Figs. 4 View FIGURE 4 B, 5A). External orbital angle dorso-ventrally flattened, distally rounded, reaching slightly beyond level of frontal margin ( Fig. 5 View FIGURE 5 A, C), continuous to anterolateral margin. Antero- and posterolateral margins ( Figs. 3 View FIGURE 3 A, 4A, 5C) almost of same length; anterolateral margin with 5 teeth excluding external orbital angle, first and second teeth, third and fourth teeth placed closer to each other, fifth tooth largest, first to fourth teeth small, almost of same size; margins between bases of teeth lined with granules, forming ridge-like structure.

Epistome ( Fig. 5 View FIGURE 5 A) with posterior margin medially produced, produced part medially notched, posterior margin rimmed, beaded, except for median notch.

Eyes small, not completely occupying orbit, slightly mobile; eyestalk with L-shaped prominence along proximal margin of cornea of anterior surface to concave part of cornea on upper surface; cornea small, width as long as length ( Figs. 4 View FIGURE 4 B, 5A, B). Distomesial angle of basal antennal segment continuous with ventral extension of distolateral angle of front ( Fig. 5 View FIGURE 5 A). First maxilliped with distinct “portunoid lobe”. Third maxilliped ( Fig. 5 View FIGURE 5 D) with ischium to merus semi-rectangular; ischium with median sinuous groove, distal margin sinuous, with produced distomesial angle, mid-length about 2 times that of merus; merus with distolateral angle almost right angle, dorso-ventrally flattened.

Thoracic sternites 3, 4 weakly divided by lateral short grooves; suture of thoracic sternites 4, 5 mesially end in elongated slit; vulva transversely elongated, longitudinally placed about middle of sternite 6; suture between sternites 6, 7 reaching to below inner end of vulva, but not connected to posterior margin of transverse median “ridge” connects sternites; median longitudinal groove between sternites 7, 8 reaching as far as median “ridge” near vulva.

Chelipeds slender, longer than ambulatory legs ( Figs. 2 View FIGURE 2 , 3 View FIGURE 3 ); merus ( Figs. 3 View FIGURE 3 , 6 View FIGURE 6 ) slightly shorter than chela, subovate in cross section with slightly concave lower surface, anterior margin with 1 subproximal small tooth, 1 subdistal small tooth; left chela ( Fig. 6 View FIGURE 6 A–C) relatively stouter; chela with swollen palm, surfaces smooth, with no striae or granules; fingers slender, as long as palm, distally hooked, 3–4 long sharp teeth and few small sharp teeth between them along cutting edges which interdigitate. Ambulatory legs ( Figs. 3 View FIGURE 3 , 7 View FIGURE 7 ) slender, P3 longest, P5 shortest, with long, fine setae, ratios of lengths of P2–P5 meri to CL 0.98, 1.03, 0.93, 0.67 respectively; propodus of P5 with subparallel inner, outer margins, slender; P5 dactylus lanceolate, dactylus narrower than propodus.

All abdominal somites ( Fig. 5 View FIGURE 5 E) free, somite 4 to telson triangular in shape; telson longer than broad, lateral margins slightly concave; pleopods setose, developed.

Coloration. Dorsal surfaces of carapace and chelipeds orange, except for the tip of the fifth anterolateral tooth, tips of two teeth on the anterior margin of cheliped merus, and occlusal margins and about distal third of cheliped fingers; ventral surfaces and ambulatory legs yellowish-white ( Figs. 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 , 6 View FIGURE 6 ).

Etymology. The new species is named after the Iejima (= Ie Island), where the holotype of the species was collected. The name is used as noun in apposition.

Common name. The standard Japanese name for this species is given here as Iejima-gama-gazami. Ecological note. Catoptrus iejima , n. sp., was collected from a submarine cave with depth of about 10 m. When the collectors checked the set trap baited with Pacific saury ( Cololabis saira ; “Sanma” in Japanese), about five individuals of this species, including a very small one, were observed to be wandering outside the trap. The crabs observed all appear to move very slowly. Although no individual was actually trapped, one female was caught by hand from outside the trap (Y. Yamada & K. Yunokawa, pers. comm.) ( Fig. 2 View FIGURE 2 ).

Remarks. Catoptrus iejima , n. sp., superficially resembles Atoportunus Ng & Takeda, 2003 , in its remarkable characters, such as the long and slender pereopods ( Figs. 3 View FIGURE 3 , 7 View FIGURE 7 ) and relatively small eyes ( Figs. 4 View FIGURE 4 B, 5A). It is noteworthy that the new species possesses all the diagnostic characters of Catoptrus A. Milne-Edwards, 1870 , e.g. laterally ovate or rounded carapace ( Fig. 4 View FIGURE 4 A), subproximal and subdistal teeth present on the anterior margin of cheliped merus ( Fig. 6 View FIGURE 6 A, D) (except in C. inaequalis ( Rathbun, 1906) and C. quinquedentatus Yang, Chen & Tang, 2006 ), almost right angled distolateral angle of the merus of the third maxilliped ( Fig. 5 View FIGURE 5 D), and straight to lanceolate dactylus of P5 ( Fig. 7 View FIGURE 7 H) ( Serène, 1966; Ng, 2011). Although no male specimen was collected, the characters of C. iejima , n. sp., best fit Catoprtus A. Milne-Edwards, 1870.

Catoptrus View in CoL currently contains five species: C. inaequalis ( Rathbun, 1906) View in CoL , C. quinquedentatus Yang, Chen & Tang, 2006 View in CoL , C. nitidus A. Milne-Edwards, 1870 View in CoL [type species], C. rathbunae Serène, 1966 View in CoL , and C. undulatipes Yang, Chen & Tang, 2006 (Ng et al., 2008) View in CoL . Catoptrus iejima View in CoL , n. sp. most closely resembles C. nitidus View in CoL and C. undulatipes View in CoL in their laterally ovate carapace outlines and the presence of two teeth on the anterior margin of each cheliped merus. However, C. iejima View in CoL , n. sp. can be readily distinguished from C. nitidus View in CoL and C. undulatipes View in CoL by its proportionately more elongated pereopods and the shape of the teeth on the anterolateral margin of the carapace. In C. iejima View in CoL , the merus of P3, for example, is 1.03 times as long as the CL ( Figs. 3 View FIGURE 3 A, 7B), while that of C. nitidus View in CoL is only 0.74 ( Fig. 8 View FIGURE 8 ). Yang et al. (2006) did not describe or indicate how long the ambulatory legs of C. undulatipes View in CoL were, but their figure of its cheliped ( Yang et al., 2006: fig. 3D) shows a merus which is clearly shorter than that of C. iejima View in CoL ( Figs. 2 View FIGURE 2 , 3 View FIGURE 3 ). Eyes of C. iejima View in CoL is reduced and not occupying the orbit ( Figs. 2 View FIGURE 2 , 4 View FIGURE 4 A, B, 5A–C). In contrast, the eyes of C. nitidus View in CoL and C. undulatipes View in CoL are developed and fully occupying the orbits ( Fig. 8 View FIGURE 8 ; Yang et al., 2006: fig. 3A, B). Furthermore, in C. iejima View in CoL , n. sp., the teeth of the anterolateral margin are relatively small, so that their bases are well apart from each other. In contrast, the teeth of C. nitidus View in CoL and C. undulatipes View in CoL are proportionately larger and wider, so the bases of the teeth are adjacent to each other ( Fig. 8 View FIGURE 8 ; Yang et al., 2006: fig. 3A).

Although C. iejima View in CoL , n. sp. and Atoportunus View in CoL species share remarkable characters, e.g. elongated pereopods and reduced eyes; they can be differentiated by the following characters. In C. iejima View in CoL , n. sp., the chelipeds are moderately stronger ( Figs. 2 View FIGURE 2 , 3 View FIGURE 3 ), the palm of the chela is more swollen and the fingers are alternatively lined with long sharp teeth and a few small sharp teeth ( Fig. 6 View FIGURE 6 ); the outline of the carapace is elliptical in dorsal view ( Figs. 3 View FIGURE 3 A, 4A, B, 5A); and the shape of the P5 propodus and dactylus are similar with those of the P2–P4 ( Fig. 7 View FIGURE 7 ). In Atoportunus View in CoL , the cheliped is very slender (Ng & Takeda, 2003: figs. 2A, 3A, 5A, 6A, 7; Takeda, 2003: figs. 1, 2E, 3); the palm is as narrow as the merus (Ng & Takeda, 2003: figs. 2A, 3A, 5A, 6A, 7; Takeda, 2003: figs. 1, 2E, 3), the very slender fingers are sparsely provided with long and thin teeth (Ng & Takeda, 2003: figs. 5B, 6C, 7; Takeda, 2003: fig. 2F); the outline of the carapace is more typical, been fan-shaped outline with stronger lobes or teeth along anterolateral margin (Ng & Takeda, 2003: figs. 2B, 3A, 4A, 6B 8A; Takeda, 2003: figs. 1A, 2A); and the propodus and dactylus of P5 are always foliaceous and widely lanceolate, respectively (Ng & Takeda, 2003: figs. 5C, 8C; Takeda, 2003: figs. 1B, 2G).