Dicranodromia erinaceus, Ng & Yang, 2021

Ng, Peter K. L. & Yang, Chien-Hui, 2021, On two new species of deep-sea carrier crabs (Crustacea, Brachyura, Homolodromiidae, Dicranodromia) from Taiwan and the Philippines, with notes on other Indo-West Pacific species, ZooKeys 1072, pp. 129-165 : 129

publication ID	https://dx.doi.org/10.3897/zookeys.1072.72978
persistent identifier	https://treatment.plazi.org/id/4F563B84-BA4F-5460-A96A-9606FBC33594
treatment provided by	ZooKeys by Pensoft
scientific name	Dicranodromia erinaceus
status	sp. nov.

Treatment

Dicranodromia erinaceus sp. nov.

Figures 7E, F View Figure 7 , 13 View Figure 13 , 14 View Figure 14 , 15 View Figure 15 , 16 View Figure 16 , 21A, B, D-F, K-M View Figure 21

Dicranodromia doederleini - Ho et al. 2004: 643, fig. 1B; Ahyong et al. 2009: 129, fig. 93 (not fig. 94); Ng et al. 2017: 27 (list). (non Dicranodromia doederleini Ortmann, 1892)

Material examined.

TAIWAN: holotype ♀ (14.0 × 18.0 mm), station CP4091, 22°14'N, 119°59'E, among numerous mud tubes, off small Liu-Qiu Island , southeast Taiwan, 974-994 m, coll. N.O. Ocean Researcher 1, 27 May 2013 (NTOU B00126 View Materials ) GoogleMaps ; paratypes 2 ♀♀ (13.2 × 17.6 mm, 13.8 × 18.5 mm), same data as holotype (ZRC 2020.0467, COI sequence: OK351335 View Materials ) GoogleMaps ; 1 ♂ (6.9 × 9.5 mm), station CP4212, 22°18.34'N, 119°59.51'E, southwestern Taiwan , 961-1008 m, coll. T.-Y. Chan, 15 Nov. 2020 (ZRC 2021.0084, COI sequence: OK331334 View Materials ) GoogleMaps ; 1 ♂ (8.2 × 12.5 mm), station CP4212, 22°18.34'N, 119°59.51'E, southwestern Taiwan , 961-1008 m, coll. T.-Y. Chan, 15 Nov. 2020 (ZRC 2021.0085) GoogleMaps . Others : 1 ♀ (7.5 × 11.1 mm, carapace badly damaged), 24°26.9'N, 122°18.1'E, Taiwan, 638-824 m, coll. R/V "Fishery Researcher 1", 4 August 2000 (NTOU B00127 View Materials ) GoogleMaps .

Diagnosis.

Carapace longitudinally subovate, widest across intestinal-mesobranchial regions; dorsal surface prominently convex, lateral surfaces covered with numerous spinules, those on median part relatively lower, sometimes granular, with short stiff setae, denser on lateral parts but not obscuring margins; short stiff setae present on pereiopods, thoracic sternum and pleon but not obscuring surface or margins. Branchiocardiac groove distinct, curving medially anteriorly. Each pseudorostral lobe triangular, inner margin straight, outer margin gently convex, directed anteriorly, inner margin with two or three spinules; exorbital tooth spiniform, directed obliquely laterally, anterior margin with two or three spinules; supraorbital margin separated from external orbital tooth by shallow concave cleft, posterior part with three spines; infraorbital margin with prominent triangular lobe, posterior margin with spinules, just visible in dorsal view. Rostrum present as one or two longer spinules in small specimens, barely discernible or just visible as a sharp granule in larger specimens. Epistome covered with spinules on anterior half; posterior half gently upturned, with median fissure, surface not covered with spinules, posterior margin entire. Basal antennal article subquadrate; surfaces covered by spinules and granules; anteroexternal tooth short. Eyes with short peduncle. Third maxilliped relatively narrow; merus subovate with low anterointernal lobe, slightly shorter than ischium; ischium subtrapezoidal, distal half wider than proximal part with inner margin convex; palp (carpus, propodus, dactylus) long, reaching to median part of ischium when folded; exopod with proximal third widest, outer margin with low sharp granules on proximal third. Chelipeds densely covered with stiff setae on most parts; merus and carpus with outer surface and margins lined with spinules and granules; palm relatively short, outer surface and margins covered with numerous sharp granules; fingers thick, wide, occluding surface hollowed; pollex with deep U-shaped depression distally. P2 and P3 relatively long, P3 longer than P2; merus with low tooth on distal extensor margin, length to width ratio of P2 and P3 merus 5.2 and 4.5, respectively; proximal part of extensor margin with low spinules, flexor margin with numerous spinules; propodus almost straight, unarmed, length to width ratio of P2 and P3 propodus 6.7 and 8.0, respectively; dactylus sickle-shaped, flexor margin lined with 15 or 16 spines, terminating in strongly incurved claw, propodus about twice length of dactylus. P4 stouter, shorter than P5; length to width ratio of P4 and P5 merus 3.5 and 5.0, respectively; proximal part of extensor margin of merus with low spinules, flexor margin with numerous spinules; P4 and P5 propodus without median spinules on outer surface, length to width ratio of P4 and P5 propodus 3.5 and 4.7, respectively, distal margin fringed by sharp spines bracketing dactylus; dactylus claw-like, strongly incurved, extensor margin unarmed, flexor margin unarmed or with two weak spines. Thoracic sternite 7 with strong transverse ridge from posterior inner part of female gonopore, lateral part raised, forming triangular tubercle, curving posteriorly to join oblique ridge formed by sternites 7 and 8 with distinct groove between them that leads to spermathecal aperture at centre of triangular tubercle. Male and female pleons with six free somites and telson; male telson distinctly subovate; female telson wide, triangular, with gently sinuous margins. G1 stout, endopod distally covered by dense long setae, subdistal part of outer margin with two lobes, proximal lobe larger, prominent; G2 endopod gradually tapering to sharp tip.

Variation.

None of the specimens examined had a spine or spinule on the extensor margin of the P5 dactylus; and outer surface of the P5 propodus was also unarmed (Fig. 21E View Figure 21 ). Most of the flexor margins of the dactylus were not armed with obvious spines or spinules, although two or three stout setae may be present.

Etymology.

The species is named after the hedgehog, Erinaceus , alluding to the spiny appearance of the carapace and legs. The name is used as a noun in apposition.

Remarks.

Dicranodromia erinaceus sp. nov. belongs to the same group of species as D. spinulosa and D. delli in its spinose carapace surface and pereiopods, slender and spiniform exorbital tooth, and an acutely triangular suborbital tooth. Dicranodromia erinaceus is most similar to D. delli from New Zealand but can be distinguished by the ischium of the third maxilliped being relatively shorter and wider especially at the distal half (Fig. 14B View Figure 14 ) (versus more slender and rectangular in D. delli , cf. Ahyong 2008: fig. 4C); proportionately shorter P2 and P3 (e.g., P3 merus 4.5 × longer than wide, propodus 8.0 × longer than wide, Figs 13A View Figure 13 , 15A View Figure 15 ) (versus P3 merus 6.6 × longer than wide, propodus 11.1 × longer than wide in D. delli , cf. Ahyong 2008: fig. 2A, 3D); the proportionately shorter and stouter P4 and P5 (e.g., P5 merus just reaches the branchiocardiac groove in dorsal position, Figs 13A View Figure 13 , 15B View Figure 15 ) (versus longer and more slender, extending beyond branchiocardiac groove in dorsal position in D. delli , cf. Ahyong 2008: fig. 2A, B); the relatively stouter palm (Fig. 14F View Figure 14 ) (versus more slender in D. delli , cf. Ahyong 2008: fig. 3B); and the proportionately wider female telson (Fig. 14A View Figure 14 ) (versus less wide in D. delli , cf. Ahyong 2008: fig. 3C). The holotype and only known specimen of D. delli , an ovigerous female 15.5 × 19.0 mm from Nukuliau Seamount in New Zealand, is comparable in size to the ovigerous female holotype of D. erinaceus (14.0 × 18.0 mm) so the differences are not size-related. The characters of P2-P5 and third maxilliped are also obvious in the smaller female paratype of D. erinaceus as well as in the smaller male paratypes.

Compared to D. spinulosa , D. erinaceus can be separated by the carapace being proportionately wider (Figs 13B View Figure 13 , 16B View Figure 16 ) (versus carapace transversely narrower in D. spinulosa , cf. Guinot 1995: fig. 21a; Ahyong 2008: fig. 1C); the median dorsal surface of the carapace covered with low sharp granules (Figs 13B View Figure 13 , 16B View Figure 16 ) (versus covered with spinules in D. spinulosa , cf. Guinot 1995: fig. 21a; Ahyong 2008: fig. 1C); the submarginal surface of the posterior margin of the epistome is unarmed (Fig. 14C, D View Figure 14 ) (versus area armed with short spines in D. spinulosa , cf. Guinot 1995: fig. 22B); the ischium of the third maxilliped relatively shorter and wider especially at the distal half (Fig. 14B View Figure 14 ) (versus more slender and rectangular in D. spinulata , cf. Guinot 1995: fig. 21c); the relatively longer P2 and P3 (e.g., P3 propodus 8.0 × longer than wide, Figs 13A View Figure 13 , 15A View Figure 15 ) (versus P3 propodus less than 7 × longer than wide), the P2 and P3 propodus twice the length of the dactylus (Fig. 15A View Figure 15 ) (versus 1.7 × in D. spinulosa ; Guinot 1995: fig. 21a; Ahyong 2008: fig. 1C); and the male telson subovate in shape (Fig. 16C View Figure 16 ) (versus triangular in D. spinulosa , cf. Guinot 1995: figs 21c, 25D). Dicranodromia spinulosa was described from three males and one female from New Caledonia, the holotype female being 7.5 × 11.0 mm; a size comparable to that of the male specimens of D. erinaceus we examined.

Ho et al. (2004) recorded D. doederleini from Taiwan from one badly damaged female specimen from northeastern Taiwan (see also Ahyong et al. 2009). The specimen is now referred to D. erinaceus .