Dicranodromia danielae, Ng & Mclay, 2005

Ng, Peter K. L. & Mclay, Colin L., 2005, Dicranodromia danielae, a new species of homolodromiid crab from the Philippines (Crustacea: Decapoda: Brachyura), Zootaxa 1029 (1), pp. 39-46 : 40-45

publication ID	https://doi.org/ 10.11646/zootaxa.1029.1.3
persistent identifier	https://treatment.plazi.org/id/071F8784-CB4C-7754-FE90-C99A51F15137
treatment provided by	Felipe
scientific name	Dicranodromia danielae
status	sp. nov.

Treatment

Dicranodromia danielae View in CoL n. sp. ( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Holotype Ovigerous female, 10.8 x 14.2 mm, Balicasag Island , Panglao , Bohol, Visayas , Philippines, in tangle nets, ca. 200300 m, coll. local shell fishermen, 2 Mar 2004, Zoological Reference Collection (catalogue number ZRC 2005.94 View Materials ), Raffles Museum of Biodiversity Research, National University of Singapore.

Comparative material. Dicranodromia doederleini Ortmann, 1892: 1 female, 7.5 x 11.1 mm (carapace damaged), Taiwan, 24°26.9’N 122°18.1’E, 638–824 m, coll. R / V “Fishery Researcher 1”, 4 Aug 2000, National Taiwan GoogleMaps Ocean University, Keelung, Taiwan .

Description. Carapace ovate, longer than broad, dorsal surfaces prominently convex, with regions poorly demarcated ( Fig. 1A, B View FIGURE 1 ); frontal margin pronounced, with 2 prominent triangular lobes separated by deep Ushaped cleft, inner margin of each lobe distinctly concave, outer margin almost straight, entire, with several spinules basally adjacent to orbit, separated from external orbital tooth by shallow but distinct notch ( Figs. 1B View FIGURE 1 , 4A View FIGURE 4 ). External orbital tooth prominent, subtruncate, with inner and outer margins subparallel, inner margin distinctly shorter, inner margin and tip with several spinules. Anterolateral margin gently convex, with numerous sharp spinules, especially on anterior part ( Figs. 1B View FIGURE 1 , 2A View FIGURE 2 , 4A View FIGURE 4 ). Posterolateral margin convex, lined with small spinules ( Figs. 1B View FIGURE 1 , 2A View FIGURE 2 ). Posterior carapace margin short, concave ( Figs. 1B View FIGURE 1 , 2A View FIGURE 2 ). Carapace covered with stiff setae, especially along margins; setae on anterolateral part of carapace less dense, interspersed with scattered small delicate sharp spinules; median and posterior surfaces smooth ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 ). Epistome, suborbital, pterygostomial and subbranchial regions, surfaces of third maxillipeds, basal antennal and antennular segments covered with small spinules ( Figs. 1B, C View FIGURE 1 , 2B View FIGURE 2 ,); posterior margin of epistome distinctly spinulate, with 3 or 4 spines on lateral parts sharper, more developed ( Figs. 2B View FIGURE 2 , 4A View FIGURE 4 ).

Chelipeds equal, surfaces densely covered with setae which obscure surface ( Fig. 1A View FIGURE 1 ). Dorsal margin of merus with a row of 5 or 6 spines on anterior twothirds, with a pair of spines positioned adjacent to each other at subdistal edge; ventral margin with a row of sharp spinules on each margin. Carpus with pronounced projection at anteroexternal angle, forming distinct “elbow” ( Fig. 1A View FIGURE 1 ), surface with scattered small sharp spinules interspersed between setae. Chelae relatively slender, not swollen; outer surface covered with setae but without visible granules or spinules, appearing smooth; fingers glabrous, smooth, subequal in length to palm, relatively stout, unpigmented, forming narrow gape when closed; cutting edges lined with evenly sized teeth ( Figs. 1A View FIGURE 1 , 3 View FIGURE 3 ).

Ambulatory legs relatively short ( Fig. 1A View FIGURE 1 ). P2 and P3 normal in form, P3 longest, covered with numerous setae but without obvious spines or teeth on articles. P4 and P5 very short, relatively stout, densely covered with stiff setae; merus and carpus unarmed; propodus of P4 with 8 or 9 long spines at distal border surrounding hooked dactylus, otherwise unarmed; propodus of P5 with 4 long spines on subproximal part, 1 long median spine and 9 – 11 long spines on distal border, surrounding hooked dactylus; carrying (subchelate) structure formed by strongly hooked dactylus opposing tightly against long spines on distal margin of propodus ( Fig. 4C View FIGURE 4 ).

Female abdomen subovate; surface covered with numerous stiff setae and small delicate sharp spinules; telson distinctly triangular ( Fig. 2C View FIGURE 2 ).

Etymology. The species is named after Danièle Guinot, a good friend and respected colleague, and the author of the last major revision of the family Homolodromiidae .

Remarks. Guinot (1995) revised the genus Dicranodromia and recognized eight species from the IndoWest Pacific: D. baffini ( Alcock & Anderson, 1899) , D. crosnieri Guinot, 1995 , D. doederleini Ortmann, 1892 , D. foersteri Guinot, 1993 , D. karubar Guinot, 1993 , D. martini Guinot, 1995 , D. nagaii Guinot, 1995 , and D. spinulata Guinot, 1995 .

Of these, D. danielae n. sp. is most similar to D. doederleini Ortmann, 1892 , in that the outer surface of its chela is smooth and not granulated. It, however, differs from D. doederleini in that the outer margin of the frontal lobe is straight ( Figs. 1B View FIGURE 1 , 4A View FIGURE 4 ) (versus concave), the external orbital tooth is subtruncate ( Figs. 1B View FIGURE 1 , 4A View FIGURE 4 ) (versus triangular), the posterior margin of the epistome is prominently spinulate (( Fig. 4B View FIGURE 4 ) versus granulated or uneven), and the meri of the P4 and P5 are proportionately stouter and shorter ( Fig. 1A View FIGURE 1 ) (e.g. maximum length to maximum width ratio of P5 merus of D. danielae is ca. 3.2 versus ca. 4.2 for D. doederleini ; cf. Guinot 1995: 202 – 208, figs. 11, 12; Ikeda 1998: 54, 55, pl. 1; Ho et al. 2004: 643, fig. 1B).

With regards to the partially spinulate dorsal carapace surface and spinulate posterior margin of the epistome, D. danielae is close to the only other known Philippine species of Dicranodromia , D. martini Guinot, 1995 , described from Cagayan and off Mindanao. Dicranodromia danielae , however, can easily be separated from D. martini as the outer surface of the chela is smooth (not prominently granulated, Fig. 3 View FIGURE 3 versus Guinot 1995: fig. 19d), the external orbital tooth is armed with spinules (not unarmed, Figs. 1A, B View FIGURE 1 , 4A View FIGURE 4 versus Guinot 1995: figs. 19a, 20A), the posterior margin of the epistome is spinulate (not crenulate, Fig. 4B View FIGURE 4 versus Guinot 1995: fig. 20B)), and the meri and propodi of P2 – P5 are proportionately shorter ( Fig. 1 View FIGURE 1 versus Guinot 1995: figs. 19a, e, 20c).

Guinot (1995: 207, Fig. 11b) identified one male specimen from Japan as “ Dicranodromia aff. doederleini ”, commenting that the spinulation on the carapace, suborbital, subhepatic, frontal, pterygostomial, buccal, epistomal, antennal and antennular surfaces as well as pereopods was generally stronger than typical D. doederleini . This specimen, nevertheless, differs from D. danielae by the same set of characters discussed earlier for D. doederleini . Guinot (1995: 208210) also discusses the problem of the poorly known D. baffini ( Alcock & Anderson 1899) , a species known only from India and possibly Japan, but this species also has a triangular external orbital tooth and granulate outer surfaces of the chelae.

The ovigerous holotype female is carrying around 35 large eggs at an early stage of development, diameter 1.7 mm. Development is direct in homolodromiids and there are no planktotrophic larval stages. This reproductive strategy has been reported for several other species of Dicranodromia ; and adult females carrying juvenile crabs have been found in D. nagaii (see Guinot 1995: 167).

Most species of Dicranodromia occur in relatively deeper waters, although D. doederleini appears to have a broader depth range. Guinot (1995: 204) and Ikeda (1998: 20, 54) report ranges of 65 – 275 m and 160 – 280 m, respectively from Japan, and Ho et al. (2004: 643) recorded a Taiwanese specimen from much deeper, between 638 and 824 m. Dicranodromia karubar Guinot, 1993 , from Indonesia and Western Australia is known from 356468 m and 434 m respectively ( Guinot 1995, Tavares 1998), D. foersteri Guinot, 1993 , from New Caledonia, Chesterfield and Vanuatu occurs between 600 and 660 m ( Guinot 1995), D. martini Guinot, 1995 , from the Philippines and Sulu Sea is known from 750930 m ( Guinot 1995), and D. spinulata Guinot, 1995 , from New Caledonia has been collected between 535 and 680 m ( Guinot 1995). According to the fishermen who collected the holotype, D. danielae was collected by tangle nets from relatively deep waters, estimated here at between 200 and 300 m.

The structure of the female spermathecal apertures, useful in differentiating some Dicranodromia species ( Guinot 1995) , could not be described for the present new species. The type specimen was badly damaged when the bottle it was contained in was accidentally crushed. This occurred just after the photographs and drawings were made. The thoracic sternum was too badly damaged to allow any descriptions to be made.