Typhlocarcinops diminutus, Ng & Rahayu, 2020
publication ID |
https://doi.org/10.11646/zootaxa.4788.1.1 |
publication LSID |
lsid:zoobank.org:pub:7A461DBA-00B7-48DB-9320-4775DA8F21B2 |
persistent identifier |
https://treatment.plazi.org/id/03C05222-FFED-FC5E-FF35-D6A5FA8EFDD1 |
treatment provided by |
Plazi (2020-06-05 09:49:28, last updated 2023-11-18 03:01:46) |
scientific name |
Typhlocarcinops diminutus |
status |
sp. nov. |
Typhlocarcinops diminutus View in CoL n. sp.
( Figs. 67–69 View FIGURE 67 View FIGURE 68 View FIGURE 69 )
Material examined. Holotype: male (3.5 × 2.5 mm) ( ZRC 2018.0295 View Materials ), dredge, station PS252, Pulau Semakau , Singapore, coll. 1990s . Paratypes: 3 males (4.2 × 2.9 mm, 2.9 × 2.4 mm, 3.3 × 2.7 mm); 2 females 3.8 × 2.9 mm, 2.9 × 2.2 mm); 1 ovigerous female (3.6 × 2.7 mm) ( ZRC 1992 View Materials 5955–5999), Pulau Semakau , Singapore, coll. 27 January 1992 .
Diagnosis. Carapace ( Figs. 67A, B View FIGURE 67 , 68 View FIGURE 68 A–D) 1.2−1.4 times broader than long, slightly narrowing on posterolat- eral margin, surface with tufts of short plumose setae, regions demarcated, H-shaped gastro-cardiac grooves shallow, indistinct, anterolateral margin arcuate, lined with small granules, separated by 3 broad, sharp teeth; posterolateral margin subparallel posterolateral surface with scattered tubercles. Front bilobed ( Figs. 67B View FIGURE 67 , 68 View FIGURE 68 B–D), with shallow median cleft, margin of each lobe convex. Orbit ( Fig. 67C View FIGURE 67 ) short, bulbous ocular peduncles filling orbit, immovable, cornea small, pigmented. Epistome ( Fig. 67C View FIGURE 67 ) relatively broad, triangular median lobe with slight median suture. Antennal peduncles long. Third maxilliped ( Figs. 67C View FIGURE 67 , 69A View FIGURE 69 ) with outer surface of merus covered with small granules on distal margin, outer margin straight, inner margin sinuous, anteroexternal angle gently produced; ischium as broad, but much longer than merus, inner margin slightly shorter than outer margin; exopod relatively slender. Chelipeds unequal in males, subequal in females ( Figs. 67 View FIGURE 67 E–G, 68A), fingers of major chela smooth, outer surface of dactylus and fixed finger with longitudinal ridge, long fine setae on upper and lower margins of dactylus and fixed finger, cutting edges with prominent broad teeth; palm, carpus and merus smooth, tufts of sparse setae on its surfaces; inner angle of carpus with sharp low tooth ( Fig. 67E View FIGURE 67 ). P2−P5 proportionally long ( Figs. 67A, H View FIGURE 67 , 68A View FIGURE 68 ); dorsal margin of the merus of first to third ambulatory legs smooth, unarmed; lateral surface, dorsal and ventral margins fringe with long setae; dactylus straight, relatively long; merus of P5 not reaching front when folded. Fused thoracic sternites 1, 2 broadly triangular ( Fig. 67C, D View FIGURE 67 ), proportionally narrow; thoracic sternites 3, 4 fused, suture discernible. Male pleon ( Fig. 69B View FIGURE 69 ) relatively broad; telson relatively short, 1.5 times as long as somite 6, with rounded distal margin. G1 ( Fig. 69C, D View FIGURE 69 ) slender, upper and lower halves subequal, moderately curved, distal part strongly curved, relatively long and slender, tapering to relatively sharp tip, with setae subdistally. Female pleon ( Fig. 68E View FIGURE 68 ) broad, somite 1 reaching coxae of fourth ambulatory legs; telson with rounded distal margin; tapering to pointed edge; vulva ( Fig. 68F View FIGURE 68 ) relatively broad, rounded.
Etymology. From the Latin “diminutus” for small sized, alluding to the small adult size of the species.
Remarks. The general appearance of the species superficially resembles members of Heteropilumnus De Man, 1895 , and its allies ( Ser Rathbun, 1931 ; Zehntneriana Ng & Takeda, 2010 ), except that it lacks the long setae that lines the margins of the carapace, chelipeds and ambulatory legs and/or the dense velvet-like tomentum that covers the carapace (cf. Ng 1989; Ng & Davie 1991; Ng & Lin 2015; Ng & Tan 1988; Ng et al. 2018; Lee et al. 2015).
Like any other species assigned to Typhlocarcinops , the anterolateral margin of carapace is varied in relation with size and sex. The larger male (carapace width 4.2 × 2.9 mm) and the females have less pronounced lobes on the anterolateral margin than the small one. The dactylus and fixed finger of the chelipeds of the larger male are without longitudinal ridge.
The species most resembles T. canaliculatus , but differs in the shape of the carapace in which the posterolateral margin is slightly narrowing, the G1 with the upper and lower halves are subequal, moderately curved in T. diminutus n. sp. ( Figs. 67A, B View FIGURE 67 , 68 View FIGURE 68 B‒D, 69C, D), versus the posterolateral margin of the carapace is parallel and the upper half of G1 is much longer than the lower half, strongly curved in T. canaliculatus ( Figs. 5B, C View FIGURE 5 , 7A, D View FIGURE 7 , 8B View FIGURE 8 , 9B, C View FIGURE 9 , 10A View FIGURE 10 , 11B View FIGURE 11 , 12B View FIGURE 12 , 13 View FIGURE 13 D‒G, I‒L, 14B‒E, H‒K, 15E‒G, 40A–C).
Type locality. Pulau Semakau , Singapore .
Distribution. Singapore; from shallow subtidal habitats with soft substrates less than 20 m depth.
Lee, S. - K., Kim, W. & Ng, P. K. L. (2015) The identity of Ceratoplax villosa Zehntner, 1894 (Crustacea: Decapoda: Pilumnidae), with description of a new species of Zehntneriana Takeda & Ng, 2010, from Japan. Journal of the Marine Biological Association, 95 (5), 983 - 989. https: // doi. org / 10.1017 / S 0025315415000016
Ng, P. K. L. & Tan, L. W. H. (1988) The identities of Heteropilumnus subinteger (Lanchester, 1900) and Heteropilumnus hirsutior (Lanchester, 1900) stat. nov., with description of a new species, Heteropilumnus holthuisi sp. nov. (Crustacea, Decapoda, Brachyura, Pilumnidae). Crustaceana, 54 (1), 13 - 24. https: // doi. org / 10.1163 / 156854088 X 00582
Ng, P. K. L. (1989) The Indo-Pacific Pilumnidae IV. On Cryptocoeloma haswelli Rathbun, 1923 (Crustacea Decapoda, Brachyura). Crustaceana, 56 (1), 47 - 57. https: // doi. org / 10.1163 / 156854089 X 00789
Ng, P. K. L. & Davie, P. J. F. (1991) The Indo-Pacific Pilumnidae VII. Notes on the taxonomy of Heteropilumnus sasekumari (Serene, 1971) and Cryptolutea Ward, 1936 (Crustacea: Decapoda: Brachyura). Memoirs of the Queensland Museum, 30 (3), 517 - 524.
Ng, P. K. L. & Lin, C. - W. (2015) Zehntneriana serrata n. sp., a new species of pilumnid crab from southern Taiwan (Crustacea, Decapoda, Brachyura). Zootaxa, 3915 (2), 263 - 271. https: // doi. org / 10.11646 / zootaxa. 3915.2.5
Ng, P. K. L., Lin, C. - W. & Ho, P. - H. (2018) On three species of reef-dwelling pilumnid crabs from Taiwan, with notes on the genus Heteropilumnus De Man, 1895 (Crustacea: Brachyura). Zoological Studies, 57, 12. pp. 1 - 17. https: // doi. org / 10.6620 / ZS. 2018.57 - 12
FIGURE 5. Typhlocarcinops canaliculatus Rathbun, 1909, holotype male (3.5 × 2.9 mm) (NHMD 5956), Gulf of Thailand. A, overall habitus; B, C, dorsal surface of carapace from different angles; D, frontal view of cephalothorax; E, dorsal view of right cheliped; F, outer view of right chela; G, outer view of left chela.
FIGURE 7. Typhlocarcinops canaliculatus Rathbun, 1909, non-type male (carapace width ca. 1.8 mm, badly crushed) (USNM 39751), Gulf of Thailand, Thailand. A, overall habitus; B, F, outer view of right chela; C, somites 1–3 of male pleon; D, dorsal view of carapace; E, left third maxilliped; G, male pleon. Scales = 0.5 mm. D–G after Rathbun (1910: fig. 32).
FIGURE 8. Typhlocarcinops canaliculatus Rathbun, 1909, male (5.5 × 4.2 mm) (ZRC 1995.0374), Singapore.A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax; D, anterior thoracic sternum; E, outer view of left chela; F, outer view of right chela.
FIGURE 9. Typhlocarcinops canaliculatus Rathbun, 1909, male (8.6 × 6.5 mm) (ZRC 1985.1385), Singapore. A, overall habitus; B, C, dorsal view of carapace; D, frontal view of cephalothorax; E, anterior thoracic sternum; F, sternopleonal cavity showing pleonal locking tubercles; G, outer view of right chela; H, outer view of left chela.
FIGURE 10. Typhlocarcinops canaliculatus Rathbun, 1909, male (8.7 × 6.5 mm) (ZRC 1984.7749), Phuket. A, dorsal view of carapace; B, anterior thoracic sternum and pleon; C, dorsal view of left cheliped; D, dorsal view of right cheliped; E, outer view of right chela; F, outer view of left chela.
FIGURE 11. Typhlocarcinops canaliculatus Rathbun, 1909, male (13.2 × 10.5 mm) (ZRC 2018.0696), Hong Kong. A, overall habitus; B, dorsal surface of carapace (denuded); C, frontal view of cephalothorax; D, anterior thoracic sternum and pleon; E, posterior thoracic sternum and pleon; F, outer view of chelae; G, dorsal view of left chela; H, dorsal view of right chela.
FIGURE 12. Typhlocarcinops canaliculatus Rathbun, 1909, female (5.8 × 4.2 mm) (ZRC 1995.0374), Singapore. A, overall habitus; B, dorsal view of carapace; C, anterior thoracic sternum and pleon; D, sternopleonal cavity and vulvae.
FIGURE 13. Typhlocarcinops canaliculatus Rathbun, 1909. A–G, male (5.5 × 4.2 mm) (ZRC 1995.0374), Singapore; H–M, male (8.6 × 6.5 mm) (ZRC 1985.1385), Singapore.A, frontal view showing orbit, epistome, antenna and antennule; B, left third maxilliped; C, H, male pleon; D, I, left G1 (ventral view); E, J, left G1 (dorsal view); F, K, distal part of left G1 (ventral view); G, L, distal part of left G1 (dorsal view); M, left G2. Scales: A–C, H = 1.0 mm; D, E, I, J, M = 0.5 mm; F, G, K, L = 0.25 mm.
FIGURE 67. Typhlocarcinops diminutus n. sp., male (3.5 × 2.5 mm) (ZRC 2018.0295), Singapore.A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax; D, anterior thoracic sternum and telson; E, subdorsal view of right cheliped (denuded); F, outer view of right chela; G, outer view of right chela (denuded); H, left fourth ambulatory leg (denuded).
FIGURE 68. Typhlocarcinops diminutus n. sp. A, B, paratype ovigerous female (3.6 × 2.7 mm) (ZRC 1992.5953), Singapore; C, E, F, paratype female (3.8 × 2.9 mm) (ZRC 1992.5954), Singapore; D, paratype male (4.2 × 2.9 mm) (ZRC 1992.5952), Singapore. A, overall habitus; B–D, dorsal view of carapace; E, anterior thoracic sternum and pleon; F, sternopleonal cavity and vulvae.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
Kingdom |
|
Phylum |
|
Class |
|
Order |
|
Family |
|
Genus |