Typhlocarcinops robustus, Ng & Rahayu, 2020

Ng, Peter K. L. & Rahayu, Dwi Listyo, 2020, A synopsis of Typhlocarcinops Rathbun, 1909 (Crustacea: Decapoda: Brachyura: Pilumnidae), with descriptions of nine new species from the Indo-West Pacific, Zootaxa 4788 (1), pp. 1-100 : 42-46

publication ID	https://doi.org/ 10.11646/zootaxa.4788.1.1
publication LSID	lsid:zoobank.org:pub:7A461DBA-00B7-48DB-9320-4775DA8F21B2
DOI	https://doi.org/10.5281/zenodo.10564037
persistent identifier	https://treatment.plazi.org/id/03C05222-FF8B-FC21-FF35-D050FC0FFC25
treatment provided by	Plazi
scientific name	Typhlocarcinops robustus
status	sp. nov.

Treatment

Typhlocarcinops robustus View in CoL n. sp.

( Figs. 35–37 View FIGURE 35 View FIGURE 36 View FIGURE 37 , 40K View FIGURE 40 )

Material examined. Holotype: male (15.2 × 11.3 mm) ( MZB Cru 4804), Minajerwi Estuary , Timika, Papua Indonesia, coll. 28 June 2004 . Paratypes: 1 female (7.3 × 5.7 mm) ( MZB Cru 4805), Arafura Sea, coll. 17 April 2000 ; 1 male (8.5 × 6.8 mm), 1 female (8.5 × 6.5 mm) ( ZRC 2018.0275 View Materials ), station 7C, Arafura Sea , 4°46’18.95’’S 136°28’02.64’’E, Papua, Indonesia, coll. 19 April 2000 GoogleMaps .

Diagnosis. Carapace ( Figs. 35A View FIGURE 35 , 36A, B View FIGURE 36 ) about 1.4 times broader than long, surface smooth, long setae on lateral margin, regions indistinct, H-shaped gastro-cardiac grooves distinct; anterolateral margin arcuate, lined with small granules, separated into 3 broad lobes; posterolateral surface and margin with scattered tubercles. Front ( Figs. 35A, B View FIGURE 35 , 36A, B View FIGURE 36 ) bilobed, with shallow median cleft, margin of each lobe convex. Orbit ( Fig. 35B View FIGURE 35 ) short, bulbous ocular peduncles filling orbit, immovable, cornea small, slightly pigmented. Epistome ( Fig. 35B View FIGURE 35 ) relatively broad, posterior margin concave.Antennal peduncles relatively long. Third maxilliped ( Fig. 37A View FIGURE 37 ) with merus broad, squarish, outer and inner margins straight, ischium slightly broader, much longer than merus, inner margin slightly shorter than outer margin, lower margin slightly oblique; exopod relatively stout. Chelipeds unequal in males, subequal in females ( Figs. 35A, F, G View FIGURE 35 , 36 View FIGURE 36 C–E), outer surface of finger of major chela smooth, with shallow longitudinal groove and scattered tubercles proximally, longitudinal groove on fixed finger, surface of palm smooth medially, upper and lower outer margin with scattered setae; cutting edges of fingers with prominent teeth; surface of carpus smooth, margin with short setae, inner angle with long, sharp teeth in larger specimens; dorsolateral margin of merus with row of large tubercles, margins covered with long setae; inner angle of carpus with low to sharp tooth ( Figs. 35E View FIGURE 35 , 36 View FIGURE 36 C–E). P2−P5 ( Fig. 35A View FIGURE 35 ) proportionally long, fringe by long setae on dorsal and ventral margins; merus of P5 not reaching front when folded. Fused thoracic sternites 1, 2 broadly triangular ( Figs. 35C View FIGURE 35 , 36G View FIGURE 36 ), proportionally narrow; thoracic sternites 3, 4 partially fused, with only lateral suture discernible. Male pleon ( Figs. 35C, D View FIGURE 35 , 37B View FIGURE 37 ) relatively broad, telson long, 1.7 times as long as somite 6, triangular. G1 ( Figs. 37 View FIGURE 37 C–F, 40K) slender, curved, upper half much longer than lower half, distal part relatively short, gently curved, with pointed tip. Anterolateral margin of female carapace with relatively lower teeth; pleon ( Fig. 36F View FIGURE 36 ) broad, somite 1 reaching coxae of fourth ambulatory legs, tapering to pointed edge; telson subtriangular; vulva ( Fig. 36G View FIGURE 36 ) large, ovate.

Etymology. From the Latin “robustus” for strong, alluding to the thick carapace.

Remarks. The shape of the third maxilliped and the G1 structure of T. robustus n. sp. resemble those of T. tonsuratus from Moreton Bay in Queensland, Australia. Typhlocarcinops robustus n. sp., however, has a broader carapace (1.4 times as broad as long) which is also thick and strongly vaulted, without any trace of tomentum of the carapace ( Figs. 35A View FIGURE 35 , 36A, B View FIGURE 36 ) (versus carapace 1.2 broader than long, covered with tomentum, and vaulted only posterolaterally in T. tonsuratus ; cf. Griffin & Campbell 1969: fig. 3A; present Fig. 34A View FIGURE 34 ), and the male pleon is proportionately much broader with the telson triangular and about 1.7 times the length of somite 6 ( Figs. 35C, D View FIGURE 35 , 37B View FIGURE 37 ) (versus the male pleon is more narrow with the telson subtriangular, and 1.8 times the length of somite 6 in T. tonsuratus ; cf. Griffin & Campbell 1969: fig. 3C; present Fig. 34D View FIGURE 34 ). Their G1 structures are different with that of T. tonsuratus having the distal third gently curved upwards and the tip is upcurved ( Griffin & Campbell 1969: fig. 6B; present Fig. 34 View FIGURE 34 E–G) (versus it is strongly sinuous with the distal part curved outwards like a hook for T. robustus Fig. 37 View FIGURE 37 C–F).

Typhlocarcinops robustus n. sp. differs from T. canaliculatus in possessing a relatively stockier carapace which is higher ( Figs. 35A, B View FIGURE 35 , 36A, B View FIGURE 36 ) (versus carapace relatively less raised in T. canaliculatus ; cf. Figs. 8B, C View FIGURE 8 , 9 View FIGURE 9 A–C, 10A, 11A, B); the anterior male thoracic sternum (notably sternites 3 and 4) are proportionately wider ( Fig. 35C View FIGURE 35 ) (versus anterior male thoracic sternites proportionately more narrower transversely in T. canaliculatus ; cf. Figs. 8D View FIGURE 8 , 9E View FIGURE 9 , 10B View FIGURE 10 , 11D View FIGURE 11 ); the male pleonal somite 6 is proportionately wider with the telson distinctly triangular in shape ( Fig. 37B View FIGURE 37 ) (versus male pleonal somite 6 more quadrate and the telson more rounded in T. canaliculatus ; cf. Figs. 13C, H View FIGURE 13 , 14G View FIGURE 14 , 15C, D View FIGURE 15 ); and the G1 distal part is relatively less distinctly curved ( Fig. 37 View FIGURE 37 C–F) (versus G1 distal part relatively more curved in T. canaliculatus ; cf. Figs. 13 View FIGURE 13 D–G, I–L, 14B–E, H–K, 15E‒G).

The inner angle of the carpus of the chelipeds and the anterolateral margin of the carapace varies in relation with the size and sex. In contrast to the holotype male, the inner angle of the cheliped in the small male and female specimens is not armed with a strong tooth but only with a broad protuberance, and the anterolateral margin of the carapace has low teeth or lobes ( Fig. 36 View FIGURE 36 C–E). These specimens are assigned to T. robustus by the same characters: the male telson is long, triangular, the same shape as in the large male holotype, the carapace is thick, fringed with long setae on the lateral margins and the chelipeds are granular on the upper and lower outer surface.

Type locality. Timika , Papua Indonesia .

Distribution. Arafura Sea, Papua. On soft sediments, 10– 40 m.