Labuanium vitatum, Ng, Peter K. L. & Davie, Peter J. F., 2011
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publication ID |
https://doi.org/ 10.5281/zenodo.206068 |
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DOI |
https://doi.org/10.5281/zenodo.6188077 |
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persistent identifier |
https://treatment.plazi.org/id/039DF108-000E-242F-F5C1-44C374DFFF46 |
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treatment provided by |
Plazi |
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scientific name |
Labuanium vitatum |
| status |
sp. nov. |
Labuanium vitatum View in CoL new species
( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 A, 3A, 4A, 5A, B, 6A, 7, 8, 10A–G)
Sesarma oceanicum — Alcock 1900: 423; George 1978: 14 [not Sesarma oceanica De Man, 1889 View in CoL = Labuanium rotundatum ( Hess, 1865) View in CoL ]
Sesarma (Episesarma) rotundata papuo -malesiaca— Nobili 1900: 510 (part). [not Sesarma (Episesarma) rotundata papuo - malesiaca Nobili, 1899]
Sesarma (Sesarma) rotundata View in CoL — Tesch 1917: 193 (in part).
Labuanium rotundatum View in CoL — Serène & Soh 1970: 401 (part); Hicks et al. 1984: 64; Davie, 2002: 221 (part); Ng & Liu 2003: 614 (part); Ng et al. 2008: 221 (in part).
Material examined. Holotype male (34.8 × 34.9 mm) ( WAM C 13977 View Materials ), 60 m above beach, on tree trunk, on track to West White Beach, Christmas I., coll. D. Merton, 11 February 1978. Paratypes: 1 male (39.5 × 38.5 mm) ( WAM C257-89), The Dales, Christmas I., coll. H. Yorkston, ca. January 1989; 1 female (35.2 × 33.6 mm) ( WAM C258- 89), Greta Beach, Christmas I., coll. H. Yorkston, 23 December 1988. Others: 1 male (22.3 × 21.8 mm) ( RMNH 1202), Tjibodas, Java, Indonesia, coll. J. Boerlarge, 1888; 1 male (25.5 × 24.9 mm) ( RMNH 1989), Nias, Indonesia, coll. E. E. W. G. Schröder, 1908; 1 male (34.5 × 33.1 mm) ( ZRC 2009.0099), Cuthbert Bay, Andaman Is., coll. P. Biswas, 2001.
4. Right third maxillipeds of Labuanium species. A, L. vitatum new, holotype male (34.8 × 34.9 mm) ( WAM C 13977 View Materials ), Christmas I.; B, L. papuomalesiacum ( Nobili, 1899) , male (38.0 × 37.4 mm) ( SMF 1971.18.5.53), Caroline Is.; C, L. scandens Ng & Liu, 2003 , male (29.6 × 28.7 mm) ( ZRC 2002.478), Taiwan.
Diagnosis. Carapace width and length subequal; antero-dorsal surfaces finely granular, posterior surfaces almost smooth ( Fig. 2 View FIGURE 2 A); posterolateral regions with fine granular oblique striae ( Fig. 2 View FIGURE 2 A); postfrontal cristae prominent, sharp, medially separated by deep cleft ( Figs. 2 View FIGURE 2 A, 3A); merus of third maxilliped in adult male longitudinally ovate, ca. twice as long as broad (Fig. 4A); inner margin of cheliped carpus with prominent triangular tooth, margins distinctly serrated in large males ( Fig. 5 View FIGURE 5 A); outer surface of chela with numerous small, closely arranged rounded granules ( Figs. 5 View FIGURE 5 A, B; 7A, B); dorsal margin of small male chela, with a non-pectinated ridge on outer edge of about 44 small granules, with 2 shorter, less distinct oblique rows of granules posterior to it ( Fig. 5 View FIGURE 5 B), in large males, ridges indistinct ( Fig. 7 View FIGURE 7 B) to almost indiscernible ( Fig. 5 View FIGURE 5 A), with granules appearing relatively larger, more scattered; dorsal surface of cheliped dactylus with row of distinct granules, about 12 in smaller males ( Fig. 5 View FIGURE 5 B), 10 or 11 in larger males ( Figs. 5 View FIGURE 5 A, 7B); outer surface of ambulatory meri weakly rugose, dorsal margin finely granulated ( Figs. 2 View FIGURE 2 A, 7C, D); male abdominal somite 6 broader than long, distal part of lateral margins convex, proximal part slightly sinuous ( Fig. 6 View FIGURE 6 A); abdominal telson as long as somite 6, subtriangular in shape with rounded tip ( Fig. 6 View FIGURE 6 A); G1 relatively stout; distal part bent about 45° from vertical, distal chitinous part relatively short, beak-like, subtruncate ( Fig. 10 View FIGURE 10 A–D).
Etymology. The name is Latin meaning for “shun” and “frustrating to find.” It alludes to the naturally secretive habits of the species.
Remarks. This species was first recorded from Christmas I. by George (1978) under the name of Sesarma oceanica De Man, 1889 (his specimen is here designated as the holotype of Labuanium vitatum new species). Sesarma oceanica is still considered a subjective junior synonym of Labuanium rotundatum ( Hess, 1865) .
Labuanium vitatum new species is superficially similar to L. papuomalesiacum but they can be easily separated by their G1 morphology. In L. papuomalesiacum , the G1 is relatively longer and the pectinated distal part is proportionately longer and almost straight ( Fig. 10 View FIGURE 10 H, I) whereas in L. vitatum new species, the G1 is proportionately shorter and the pectinated distal part is shorter and gently sinuous ( Fig. 10 View FIGURE 10 A, B). The lateral carapace margin of larger adult L. papuomalesiacum is also relatively more convex ( Figs. 2 View FIGURE 2 B, 9) (relatively straighter in similarly sized L. vitatum new species, Figs. 2 View FIGURE 2 A, 8), the merus of the third maxilliped is relatively shorter (Fig. 4B) (relatively longer in L. vitatum new species, Fig. 4A), and the dorsomarginal ridge of granules on the chela of L. papuomalesiacum is distinct in adult males ( Fig. 5 View FIGURE 5 C) (diffuse and poorly demarcated in large L. vitatum new species, Figs. 5 View FIGURE 5 A, 7B). These differences also apply for L. scandens ( Fig. 2 View FIGURE 2 C).
Variation. The second anterolateral tooth of the paratype female is more prominent than in the males. The inner angle of the cheliped carpus also has a distinct large triangular tooth which is dorso-ventrally flattened and appears almost lobiform; whereas in males, it is less prominent and the margins appear almost serrated ( Fig. 5 View FIGURE 5 A). The gastric regions of the males are also slightly more swollen. The two relatively small specimens from Nias (RMNH 1989) and Java (RMNH 1202) ( Fig. 8 View FIGURE 8 A, B) resemble the types from Christmas I. except that the granules lining the outer marginal ridge on the chela are distinct ( Fig. 5 View FIGURE 5 B); and the lateral margins of the G1 are relatively more sinuous ( Fig. 10 View FIGURE 10 F, G). We also tentatively refer one male from Andaman Is. (ZRC 2009.0099) to this species although it is peculiar in having a relatively smoother dorsal carapace surface, lower anterolateral teeth and proportionately longer ambulatory propodi ( Fig. 8 View FIGURE 8 C). Its G1 structure, however, agrees very well with the holotype male of L. vitatum new species. Because this male specimen is not fully hardened (it had moulted shortly before it was preserved) and both its chelae are missing, it nevertheless seems best to refer it to L. vitatum new species, for the moment.
Colour. The colour appears to be somewhat variable. An adult male (paratype, 39.5 × 38.5 mm, WAM C257- 89) was a uniform yellowish brown overall ( Fig. 1 View FIGURE 1 C) while a smaller female (paratype, 35.2 × 33.6 mm, WAM C258-89) was more brightly coloured, with a purplish carapace with beige lateral margins, with the legs pale purple, and the palm bright purple with red fingers ( Fig. 1 View FIGURE 1 A, B). The eyes are bright greenish-yellow in both specimens. The holotype male (34.8 × 34.9 mm, WAM C 13977 View Materials ) was described on the label as “Deep brownish-purplish on carapace and legs. Hands purplish with vertical (narrow) white stripe between bases of pollex and dactylus on both inner and outer surfaces of hand”. Hicks et al. (1984: 64) notes that it is known as the “White-stripe crab” in Christmas I. because of the beige lateral carapace margins.
Notes on habits. Like most of its congeners, Labuanium vitatum new species is an arboreal species, and has been collected usually at the base of trees in relatively close proximity to the sea (although one specimen was obtained on a vegetated limestone platform at 60 m altitude). Hicks et al. (1984: 64) notes that individuals grow up to 40 mm in carapace width and spawn about the time of the full moon between November and April. The chief warden on Christmas I., Max Orchard, has spent many years on the island and despite a strong personal interest in crabs, has seen this species only once on the night of 15 April 2010 at Andersons Dale, and he noted “… I was walking back up along the stream in pouring rain and edging around a tree when I caught a glimpse of a crab with bright yellow eyes and brownish carapace on a tree about 1.5 metres above the ground” (M. Orchard, personal communication). As with L. rotundatum from Guam and L. scandens from Taiwan, they are apparently mostly active mainly in wet weather and at night ( Ng & Liu 2003).
Distribution. Christmas I. ( Hicks et al. 1984); Nicobar Is. ( Alcock 1900), Nias ( Nobili 1899, 1900), west Java ( Tesch 1917).
Comparative material. In addition to the specimens listed in Ng & Liu (2003) for L. rotundatum sensu lato and L. scandens , the following new material was examined: Labuanium scandens Ng & Liu, 2003 — 1 male (29.6 × 28.7 mm), 1 female ( ZRC 2002.478), Hsiang Chiao Wan, Kentin National Park, southern Taiwan, coll. P. K. L. Ng & C. H. Wang, 5 August 2002. Labuanium rotundatum — 2 males (24.0 × 24.2 mm, 26.5 × 27.5 mm), 2 females (24.7 × 24.7 mm; 17.9 × 17.8 mm) (syntypes of Sesarma gardineri Borradaile, 1900 ) (Cambridge University Zoology Museum), Ellice Is., Funafuti, Tuvalu, coll. J. S. Gardiner, 1897.
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.
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Labuanium vitatum
| Ng, Peter K. L. & Davie, Peter J. F. 2011 |
Labuanium rotundatum
| Ng 2003: 614 |
| Davie 2002: 221 |
| Hicks 1984: 64 |
| Serene 1970: 401 |
Sesarma (Sesarma) rotundata
| Tesch 1917: 193 |
Sesarma oceanicum
| George 1978: 14 |
| Alcock 1900: 423 |
Sesarma (Episesarma) rotundata papuo
| Nobili 1900: 510 |