Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986

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 : 31-37

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-FFBC-FC28-FF35-D6A5FA89FA3B
treatment provided by	Plazi
scientific name	Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986
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Treatment

Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986 View in CoL

( Figs. 2C View FIGURE 2 , 25–30 View FIGURE 25 View FIGURE 26 View FIGURE 27 View FIGURE 28 View FIGURE 29 View FIGURE 30 , 40 View FIGURE 40 G–I)

Typhlocarcinops ocularia View in CoL — Takeda & Miyake 1968: 571, pl. 6B, fig. 9 (not Typhlocarcinops ocularia Rathbun, 1914 View in CoL )

Typhlocarcinops denticarpes Dai, Yang, Song & Chen, 1986: 384 View in CoL , text fig. 202(1) (incorrectly labelled as Typhlocarcinops canaliculatus Rathbun, 1909 View in CoL ), 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 View in CoL ), pl. 56(1).

Material examined. 1 male (11.4 × 8.6 mm) ( ZRC 2018.0694 View Materials ), Lantau , Hong Kong, coll. University of Hong Kong trawls, 11 November 2014 ; 1 male (15.9 × 12.4 mm) ( ZRC 2018.0700 View Materials ), station S1, Hong Kong, coll. University of Hong Kong trawls, 17 January 2014 ; 1 male (14.3 × 10.7 mm) ( ZRC 2016.0686 View Materials ), 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 View FIGURE 25 , 26B View FIGURE 26 , 27B View FIGURE 27 ) 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 View FIGURE 25 , 26B, C View FIGURE 26 , 27B, C View FIGURE 27 ) bilobed, with shallow median cleft, margin of each lobe slightly convex. Orbit ( Figs. 25C View FIGURE 25 , 26D View FIGURE 26 , 27C View FIGURE 27 ) short, bulbous ocular peduncles filling orbit, immovable, cornea small, slightly pigmented. Epistome ( Figs. 25C View FIGURE 25 , 26D View FIGURE 26 , 27C View FIGURE 27 ) relatively broad, broadly triangular median lobe with median suture. Antennal peduncles relatively long. Third maxilliped ( Figs. 26C View FIGURE 26 , 29A View FIGURE 29 , 30A View FIGURE 30 ) 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 View FIGURE 25 , 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 View FIGURE 25 ); lower outer surface of merus with scattered tubercles, margins covered with short setae. P2−P5 ( Figs. 25A View FIGURE 25 , 26A, G View FIGURE 26 , 27A View FIGURE 27 ) 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 View FIGURE 25 , 26E View FIGURE 26 , 27E View FIGURE 27 ), proportionally narrow; thoracic sternites 3, 4 partially fused, with only lateral suture discernible. Male pleon ( Figs. 25D View FIGURE 25 , 26E View FIGURE 26 , 27E View FIGURE 27 , 29B, G View FIGURE 29 , 30B View FIGURE 30 ) relatively narrow, telson long, about 1.7 times as long as somite 6, subtriangular with rounded distal margin. G1 ( Figs. 28 View FIGURE 28 , 29 View FIGURE 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 .

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 View FIGURE 25 , 26F View FIGURE 26 , 27D View FIGURE 27 ) (versus outer surface of the chela with numerous small granules on the median part in T. canaliculatus ; cf. Figs. 5F, G View FIGURE 5 , 7B View FIGURE 7 , 8E, F View FIGURE 8 , 9G, H View FIGURE 9 , 10E, F View FIGURE 10 , 11F View FIGURE 11 ); the inner angle of the carpus of the cheliped has a strong projected tooth ( Figs. 25F, G View FIGURE 25 , 27A View FIGURE 27 ) (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 View FIGURE 5 , 10C, D View FIGURE 10 , 11G, H View FIGURE 11 ); 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 View FIGURE 29 , 30B View FIGURE 30 ) (versus male pleon relatively wider with the lateral margins of somite 3 clearly angular in large specimens of T. canaliculatus ; cf. Figs. 13C, H View FIGURE 13 , 14G View FIGURE 14 , 15C, D View FIGURE 15 ); and the G1 has the lower half about subequal to the upper half ( Figs. 28 View FIGURE 28 , 29 View FIGURE 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 View FIGURE 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 View FIGURE 25 , 27A View FIGURE 27 ) (versus inner angle of the carpus of the cheliped low in T. decrescens ; Figs. 19F View FIGURE 19 , 20C View FIGURE 20 , 21D View FIGURE 21 , 22G, H View FIGURE 22 ); the male pleon is proportionately transversely narrower ( Figs. 29B, G View FIGURE 29 , 30B View FIGURE 30 ) (versus proportionately broader in T. decrescens ; Figs. 23G View FIGURE 23 , 24H View FIGURE 24 ); and the distal part of the G1 is gently bent and not elongate ( Figs. 28 View FIGURE 28 , 29 View FIGURE 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 View FIGURE 23 B–E, H–K, 24A–G, 40D‒F).

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.