Typhlocarcinops atimovatae, 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 : 57-60

Typhlocarcinops atimovatae n. sp.

( Figs. 47–49 )

Material examined. Holotype: male (15.9 × 11.9 mm) (MNHN-IU-200-4369a), station CP3584, Chautelier Nosy Be 11, 25º28’S 44º25’E, Madagascar, 203–210 m, coll. Expedition Atimo Vatae, 10 May 2010 . Paratypes: 15 males (smallest 7.0 × 5.3 mm), 26 females (largest 13.9 × 10.4 mm, smallest 9.0 × 6.6 mm) (MNHN-IU-200-4369b), 4 males, 2 females ( ZRC 2018.0720 ), same data as holotype . Paratypes: 1 male (18.2 × 13.1 mm), 1 female (17.4 × 13.4 mm) (MNHN-IU-2010-4370), station CP 3590, southwest Point Barrow , 25°03’S 43°59’E, 300–309 m, south Madagascar, coll. 11 May 2010 ; 2 males (12.9 × 9.8 mm, 14.1× 10.2 mm), 1 female (11.8 × 8.8 mm) (MNHN-IU- 2010-4359), station CP 3584, southeast of Point Barrow , 25°28’S 44°25’E, 203–210 m, south Madagascar, coll. 10 May 2010 ; 1 female (6.5 × 4.8 mm) (MNHN-IU-2010-4362), station CP 3584, southeast of Point Barrow , 25°28’S 44°25’E, 203–210 m, south Madagascar, coll. 10 May 2010 ; 1 male (14.3 × 10.8 mm) (MNHN-IU-2010-4368), station CP 3594, southwest of Point Barrow , 25°07’S 44°01’E, 264–268 m, south Madagascar, coll. 11 May 2010 ; 1 female (10.2 × 7.9 mm) (MNHN-IU-2010-4365), station CP 3540, Fort Dauphin area , 25°26’S 47°05’E, 189–217 m, south Madagascar, coll. 3 May 2010 ; 1 male (13.8 × 10.8 mm) ( ZRC 2018.0727 ), station CP 3583, southwest of Point Barrow , 25°31’S 44°16’E, 216–302 m, south Madagascar, coll. 10 May 2010 . All specimens collected by Expedition Atimo Vatae.

Diagnosis. Carapace ( Figs. 47A, B , 48A ) about 1.3–1.4 times broader than long, surface with granules anteriorly, posteriorly, regions not indicated; anterolateral margin arcuate, lined with tiny granules, entire or with 2 low dentations forming 3 broad lobes. Front ( Fig. 47B, C ) bilobed, with shallow median cleft, margin of each lobe slightly convex. Orbit ( Fig. 47C ) short, bulbous ocular peduncles filling orbit, immovable, cornea small, slightly pigmented. Epistome ( Fig. 47C ) relatively broad, concave. Antennal peduncles relatively long. Third maxilliped ( Fig. 49A ) with merus broad, anterolateral corner rounded, outer and inner margins straight, ischium as broad as and, longer than merus, inner margin shorter than outer margin, lower margin slightly oblique; exopod relatively stout, tip reaching to just before distal edge of merus, inner margin with distinct tooth. Chelipeds unequal in males, subequal in females ( Figs. 47A, G , 48A, D ), chela smooth; outer surface of fingers with longitudinal ridge on dactylus and fixed finger, continue to palm; outer lower margin of palm with tubercles; cutting edges of fingers with prominent teeth; inner angle of carpus with short sharp spines, one usually longer ( Fig. 47E ). P2−P5 ( Figs. 47A, F , 48A ) proportionally short, fringe by sparse long setae on dorsal and ventral margins; merus of P5 not reaching front when folded. Fused thoracic sternites 1, 2 broadly triangular ( Fig. 47D ), proportionally broad; thoracic sternites 3, 4 partially fused, with only lateral suture discernible. Male pleon ( Figs. 47D , 49B ) relatively narrow, telson long, 1.9 times as long as somite 6, subrectangular with rounded distal margin. G1 ( Fig. 49 C–F) slender, slightly curved, upper half longer than lower half, distal part directed obliquely upwards with pointed tip. Female pleon ( Fig. 48B ) broad, telson subtriangular; vulva ( Fig. 48C ) slit-like, with flap-like sternal vulvar cover.

Etymology. The species is named after the expedition, Atimo Vatae, which is a Malagasy expression for “deep south” of Madagascar. The name is used as a noun in apposition.

Remarks. Typhlocarcinops atimovatae n. sp. is in the same group of species of T. ocularius Rathbun, 1914 , T. hadrotes n. sp., with the carapace more rounded, anterolateral margins entire or almost so, and the male pleon transversely narrow (especially somites 4–6 and telson). In the form of the G1, T. atimovatae n. sp. ( Fig. 49 C–F) is most similar to T. ocularius ; but the posterolateral margin of T. atimovatae n. sp. is more sharply towards the posterior carapace margin ( Fig. 47B ) (versus posterolateral margins gently converging in T. ocularius ; Fig. 45A, B ); the dorsal carapace surface is less prominently convex ( Fig. 47C ) (versus dorsal carapace surface distinctly convex in T. ocularius ; Fig. 45C ); the ambulatory meri are proportionately longer ( Fig. 47A, F ) (versus ambulatory meri proportionately shorter in T. ocularius ; Fig. 45A ); the male telson is relatively longer ( Figs. 47D , 49B ) (versus male telson relatively shorter in T. ocularius ; Fig. 45E ); and the pollex of the major chela is not bent at an angle ( Fig. 47G ) (versus pollex of major male chela strongly bent in T. ocularius ; Fig. 45G ).

From T. hadrotes n. sp., T. atimovatae n. sp. can be distinguished by its more strongly converging posterolateral margins ( Fig. 47B ) (versus gently converging in T. hadrotes n. sp.; Fig. 50B ); the dorsal carapace surface is less prominently convex ( Fig. 47C ) (versus dorsal carapace surface distinctly convex in T. hadrotes n. sp.; Fig. 50C ); proportionately longer male telson ( Figs. 47D , 49B ) (versus male telson distinctly shorter in T. hadrotes n. sp.; Figs. 50D , 52B ); the pollex of the major chela is not bent at an angle ( Fig. 47G ) (versus pollex of major male chela strongly bent in T. hadrotes n. sp.; Fig. 50E ); and most significantly, the G1 with upper half longer than lower half, distal part slightly curved and the tip directed obliquely upwards ( Fig. 49 C–E) (versus G1 with upper half much longer than lower half, much less curved with the distal part straighter, directed upwards and the tip slightly bent, pointed in T. hadrotes n. sp.; Fig. 52 C–H) (see also discussion for T. hadrotes n. sp.).

Type locality. Madagascar .

Distribution. Known only from Madagascar at the moment. From depths of 203– 210 m.

Figures

FIGURE 45. Typhlocarcinops ocularius Rathbun, 1914, holotype male (17.0 × 13.5 mm) (USNM 46408), between Samar and Masbate, Philippines. A, overall habitus; B, dorsal view of carapace (right side denuded); C, frontal view of cephalothorax; D, right third maxilliped; E, anterior thoracic sternum and pleon; F, posterior thoracic sternum and pleon; G, outer view of right chela; H, outer view of left chela.

FIGURE 47. Typhlocarcinops atimovatae n. sp., holotype male (15.9 × 11.9 mm) (MNHN-IU-200-4369a), Madagascar. A, overall habitus; B, dorsal view of carapace (right side denuded); C, frontal view of cephalothorax; D, anterior thoracic sternum and pleon; E, carpus of right cheliped; F, left fourth ambulatory leg; G, outer view of chelae.

FIGURE 48. Typhlocarcinops atimovatae n. sp., paratype female (13.9 × 10.4 mm) (MNHN-IU-200-4369b), A, overall habitus; B, anterior thoracic sternum and pleon; C, sternopleonal cavity and vulvae; D, outer view of chelae.

FIGURE 49. Typhlocarcinops atimovatae n. sp., holotype male (15.9 × 11.9 mm mm) (MNHN-IU-200-4369a), Madagascar. A, left third maxilliped; B, pleon; C, left G1 (ventral view); D, left G1 (dorsal view); E, distal part of left G1 (ventral view); F, dista part of left G1 (dorsal view). Scales: A–D = 1.0 mm; E, F = 0.5 mm.

FIGURE 50. Typhlocarcinops hadrotes n. sp., holotype male (17.5 × 14.5 mm) (MZB Cru 4813), southern Java. A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax; D, anterior thoracic sternum and pleon; E, outer view of chelae.

FIGURE 52. Typhlocarcinops hadrotes n. sp., holotype male (17.5 × 14.5 mm) (MZB Cru 4813), southern Java. A, left third maxilliped; B, male pleon; C, left G1 (ventral view); D, left G1 (marginal view); E, left G1 (dorsal view); F, distal part of left G1 (ventral view); D, distal part of left G1 (marginal view); E, distal part of left G1 (dorsal view). Scales: A–E = 1.0 mm; F–H = 0.5 mm.