A synopsis of Typhlocarcinops Rathbun, 1909 (Crustacea: Decapoda: Brachyura: Pilumnidae), with descriptions of nine new species from the Indo-West Pacific Author Ng, Peter K. L. Author Rahayu, Dwi Listyo text Zootaxa 2020 2020-06-05 4788 1 1 100 journal article 10.11646/zootaxa.4788.1.1 1175-5326 3878222 7A461DBA-00B7-48DB-9320-4775DA8F21B2 Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 ( Figs. 2C , 25–30 , 40 G–I) Typhlocarcinops ocularia — Takeda & Miyake 1968: 571 , pl. 6B, fig. 9 (not Typhlocarcinops ocularia Rathbun, 1914 ) Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986: 384 , text fig. 202(1) (incorrectly labelled as Typhlocarcinops canaliculatus Rathbun, 1909 ), pl. 56(1); Ng 1987: 78 ; Ng et al. 2008: 144 . Typhlocarcinops denticarpus — Dai & Yang 1991: 414 , text fig. 202(1) (incorrectly labelled as Typhlocarcinops canaliculatus Rathbun, 1909 ), pl. 56(1). Material examined . 1 male (11.4 × 8.6 mm ) ( ZRC 2018.0694 ), Lantau , Hong Kong , coll. University of Hong Kong trawls, 11 November 2014 ; 1 male (15.9 × 12.4 mm ) ( ZRC 2018.0700 ), station S1, Hong Kong , coll. University of Hong Kong trawls, 17 January 2014 ; 1 male (14.3 × 10.7 mm ) ( ZRC 2016.0686 ), from fish port, 15–20 m , Amakusa , Tomioka , Kyushu , Japan , coll. J. Lai , 3 April 2004 ; 1 female (9.5 × 7.3 mm ) (NSMT-Cr 8295), Ariake Sea , Japan , coll. Seikei National Fisheries Research Institute , September 1958 . Diagnosis . Carapace ( Figs. 25B , 26B , 27B ) about 1.3 times broader than long, surface with granules anteriorly and posteriorly, regions indistinct, H-shaped gastro-cardiac grooves relatively shallow but indicated in adults; anterolateral margin arcuate, lined with tiny granules, entire, or with slightly indicated 2 lobes separated by shallow fissure. Front ( Figs. 25B, C , 26B, C , 27B, C ) bilobed, with shallow median cleft, margin of each lobe slightly convex. Orbit ( Figs. 25C , 26D , 27C ) short, bulbous ocular peduncles filling orbit, immovable, cornea small, slightly pigmented. Epistome ( Figs. 25C , 26D , 27C ) relatively broad, broadly triangular median lobe with median suture. Antennal peduncles relatively long. Third maxilliped ( Figs. 26C , 29A , 30A ) with merus 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 slender, tip reaching to just before distal edge of merus, inner margin with distinct tooth. Chelipeds unequal in males ( Figs. 25A , E–G, 26A, F, 27A, D), outer surface of fingers of chela smooth, with longitudinal ridge and scattered tubercles proximally on dactylus; lower margin of fixed finger with longitudinal rim continue to midlength of palm, surface of palm smooth sparse setae on upper margin proximally; cutting edges of fingers with prominent teeth; upper outer surface of carpus smooth, short, prominent, inner angle with strong dentiform projection ( Fig. 25F, G ); lower outer surface of merus with scattered tubercles, margins covered with short setae. P2−P5 ( Figs. 25A , 26A, G , 27A ) proportionally long, 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 ( Figs. 25D , 26E , 27E ), proportionally narrow; thoracic sternites 3, 4 partially fused, with only lateral suture discernible. Male pleon ( Figs. 25D , 26E , 27E , 29B, G , 30B ) relatively narrow, telson long, about 1.7 times as long as somite 6, subtriangular with rounded distal margin. G1 ( Figs. 28 , 29 C–F, H–J, 30C–F, 40G–I) slender, upper and lower halves subequal, strongly curved, distal part relatively long, gently bent, sinuous with pointed tip. Remarks . Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 , was described from a single male specimen (15.4 × 12.0 mm) from Guangdong , southern China . The authors noted that this species was close to T. decrescens except that it had “a denticle at the inner angle of the carpus of the chelipeds” ( Dai et al. 1986: 385 ). The figures provided by Dai et al. (1986 : pl. 56(1)) and Dai & Yang (1991 : pl. 56(1)) of the holotype of T. denticarpes do show a distinct projected angle at the inner margin of the carpus. The G1 of T. denticarpes figured by these authors is different from what they figured of “ T. canaliculatus ”, with the upper half longer than the lower half, and the distal part relatively longer and gently tapering to a more elongate cylinder ( Dai et al. 1986 : fig. 202(2); Dai & Yang 1991 : fig. 202(2)) (versus G1 with upper half as long as the lower half, and the distal part relatively shorter and more strongly tapering to a sharp point; cf. Dai et al. 1986 : fig. 202(2); Dai & Yang 1991 : fig. 202(2)). The series of specimens from Hong Kong which is close to the type locality of T. denticarpes in Guangdong, agree well with the figure of the overall habitus of T. denticarpes provided by Dai et al. (1986) and Dai & Yang (1991) . All specimens of both sexes possess a strong dentiform projection on the inner angle of the carpus of the cheliped. The G1s of these specimens, however, do not agree with that figured by Dai et al. (1986) and Dai & Yang (1991) of T. denticarpes but instead matches what they figured as “ T. canaliculatus ”. The authors tried to examine the type specimen of T. denticarpes in the Institute of Zoology in the Academia Sinica, Beijing; but it could not be found and is currently misplaced (Meng Kai, pers. comm.). Fortunately, the two specimens (one male, one female) of “ T. canaliculatus ” studied by Dai et al. (1986) and Dai & Yang (1991) were located and examined. The male from Xiamen, Fujian (6.1 × 4.5 mm , AS 2137) is in a bottle which has a vial containing two different left G1s. The larger G1 matches well that figured for their “ T. cana- liculatus ” whereas the smaller one is similar to that for T. denticarpes . The larger left G1 of what they figured as “ T. canaliculatus ” is intact whereas that of what they figured as T. denticarpes has the basal part severed. Dai et al. (1986) and Dai & Yang (1991) must have inadvertently placed the G1s of both species in the same vial and mixed them with the bottle of their “ T. canaliculatus ”. No right G1s were found. The male pleon of the specimen is intact and on the left side, there is a basal part of the smaller G1 still attached. This part matches the G1 they figured as “ T. denticarpes ” which has the basal part missing, and it is obvious that the broken G1 was previously attached to the male pleon in question. The problem is that this pleon fits exactly onto the sternopleonal cavity of the male specimen of “ T. canaliculatus ”. They also are in the same state of preservation. The information here agrees with what is known; the type male of T. denticarpes is more than twice the size of the male of “ T. canaliculatus ” (15.4 × 12.0 mm versus 6.1 × 4.5 mm ); and the smaller G1 actually belongs to what they call “ T. canaliculatus ”. As such, it is clear that Dai et al. (1986) and Dai & Yang (1991) had accidentally transposed the figures for their “ T. canaliculatus ” and T. denticarpes . FIGURE 25 . Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 , male (11.4 × 8.6 mm) (ZRC 2018.0694), Hong Kong. A, overall habitus; B, dorsal surface of carapace (denuded); C, frontal view of cephalothorax; D, anterior thoracic sternum and pleon; E, outer view of chelae; F, dorsal view of left chela; G, dorsal view of right chela. FIGURE 26 . Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 , male (15.9 × 12.4 mm) (ZRC 2018.0700), Hong Kong. A, overall habitus; B, dorsal view of carapace and right carpus of cheliped; C, left third maxilliped; D, frontal view of cephalothorax; E, anterior thoracic sternum and pleon; F, outer view of chelae; G, left fourth ambulatory leg. FIGURE 27 . Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 , male (14.3 × 10.7 mm) (ZRC 2016.0686), Kyushu, Japan. A, overall habitus; B, dorsal view of carapace; C, frontal view of cephalothorax; D, anterior thoracic sternum and pleon; E, outer view of chelae; F, dorsal view of left chela; G, dorsal view of right chela.. FIGURE 28 . Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 , holotype male (15.4 × 12.0 mm), Guangdong, China. A, right G1 (ventral view); B, distal part of right G1 (ventral view); C, left G1 (ventral view, setae not drawn); D, left G1 (dorsal view, setae not drawn); E, distal part of left G1 (ventral view, setae not drawn); F, distal part of left G1 (dorsal view, setae not drawn). A, B, after Dai et al. (1986 : text fig. 202(1)), incorrectly labelled as “ Typhlocarcinops canaliculatus Rathbun, 1909 ”. Scales = 0.5 mm. As discussed earlier, what Dai et al. (1986) and Dai & Yang (1991) call “ T. canaliculatus ” is actually T. decrescens s. str. as defined here. The external features of the specimens, and more importantly the actual structure of the G1 as elucidated here, leaves no doubt. The actual G1 of T. denticarpes agrees well with what is here figured for this species, and there is now no doubt that the specimens from Hong Kong and Japan belong to this species. Dai & Yang (1991: 16 , 413, 414) consistently spelled the name of the species as “ Typhlocarcinops denticarpus ”, but this must be regarded as an incorrect spelling. The original spelling must be maintained regardless under current ICZN (1999) rules (see also Ng 1992 ). Typhlocarcinops denticarpes is superficially similar to T. canaliculatus ; but comparisons of similarly sized specimens show several distinct differences: the outer surfaces of the chela has the median part almost smooth ( Figs. 25E , 26F , 27D ) (versus outer surface of the chela with numerous small granules on the median part in T. canaliculatus ; cf. Figs. 5F, G , 7B , 8E, F , 9G, H , 10E, F , 11F ); the inner angle of the carpus of the cheliped has a strong projected tooth ( Figs. 25F, G , 27A ) (versus inner angle of the carpus of the cheliped is low, the margin has denticles or tubercles but never with an elongate dentiform projection in T. canaliculatus ; Figs. 5E , 10C, D , 11G, H ); the male pleon is proportionately more slender transversely with the lateral margins of somite 3 relatively rounded even in large specimens (over 10 mm carapace width) ( Figs. 29B, G , 30B ) (versus male pleon relatively wider with the lateral margins of somite 3 clearly angular in large specimens of T. canaliculatus ; cf. Figs. 13C, H , 14G , 15C, D ); and the G1 has the lower half about subequal to the upper half ( Figs. 28 , 29 C–F, H–J, 30C–F, 40G–I) (versus lower half of G1 distinctly shorter than the upper half in T. canaliculatus ; cf. Figs. 13 D–G, I–L, 14B–E, H–K, 40A–C). Compared to T. decrescens , T. denticarpes has the inner angle of the carpus of the cheliped possessing a strong projected tooth ( Figs. 25F, G , 27A ) (versus inner angle of the carpus of the cheliped low in T. decrescens ; Figs. 19F , 20C , 21D , 22G, H ); the male pleon is proportionately transversely narrower ( Figs. 29B, G , 30B ) (versus proportionately broader in T. decrescens ; Figs. 23G , 24H ); and the distal part of the G1 is gently bent and not elongate ( Figs. 28 , 29 C–F, H–J, 30C–F, 40G‒I) (versus distal part of the G1 strongly curved and prominently elongate in T. decrescens ; Fig. 23 B–E, H–K, 24A–G, 40D‒F). FIGURE 29 . Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 . A–F, male (11.4 × 8.6 mm) (ZRC 2018.0694), Hong Kong; G–J, male (15.9 × 12.4 mm) (ZRC 2018.0700), Hong Kong. A, left third maxilliped; B, G, male pleon; C, H, left G1 (ventral view); D, left G1 (dorsal view); E, I, distal part of left G1 (ventral view); F, J, distal part of left G1 (dorsal view). Scales: A, B, G = 1.0 mm; C–F, H–J = 0.5 mm. FIGURE 30 . Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 , male (14.3 × 10.7 mm) (ZRC 2016.0686), Kyushu, Japan. A, left third maxilliped; B, male pleon; C, left G1 (ventral view); D, left G1 (dorsal view); E, distal part of left G1 (ventral view); F, distal part of left G1 (dorsal view). Scales: A, B = 1.0 mm; C–F = 0.5 mm. The “ Typhlocarcinops ocularia ” of Takeda & Miyake (1968) is likely to be T. denticarpes . Their figures of the chelae and G1 ( Takeda & Miyake 1968 : fig. 9) agree well with the present definition of the species; and in addition, they noted that the “inner angle of the carpus is armed with a granular blunt tooth” ( Takeda & Miyake 1968: 572 ), although this is not visible on their figure ( Takeda & Miyake 1968 : pl. 6B). Type locality . Guangdong , southern China . Distribution . Hong Kong to southern China , and Japan . On soft sediments at depths of 15– 20 m .