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Redescription of Vellumnus penicillatus (Gordon, 1930) from Hong Kong and description of a new species from Macclesfield Bank, South China Sea (Crustacea: Brachyura: Pilumnidae)

Abstract

The poorly known pilumnid, Vellumnus penicillatus (Gordon, 1930), is redescribed by examining the Hong Kong types. A new species, Vellumnus tki n. sp., is described from Macclesfield Bank, South China Sea, and it is distinguished from its closest congener, Vellumnus minabensis (Sakai, 1969) from Japan, by the setal pattern on the carapace and pereiopods, carapace proportions, structure of the front and anterolateral teeth, armature on the chelipeds and relatively shorter ambulatory legs.

Keywords
Japan; new species; taxonomy; Vellumnus Ng; 2010; V. minabensis; V. tki

INTRODUCTION

PlanopilumnusBalss, 1933Balss H 1933. Beitrage zur kenntnis Gattung Pilumnus und verwandter Gattungen. Capita Zoologica, 4(3): 1-47. (type species: Pilumnus spongiosusNobili, 1906Nobili G 1906. Diagnoses préliminaires de 34 espèces et variétés nouvelles, et de 2 genres nouveaux de Décapodes de la Mer Rouge. Bulletin du Muséum national d’Histoire naturelle, Paris, 11(6)1905(1906): 393-411. https://biostor.org/reference/134986
https://biostor.org/reference/134986...
) was revised by Ng (2010Ng PKL 2010. On the Planopilumnidae Serène, 1984 (Crustacea: Brachyura: Pseudozioidea), with diagnoses of two new pilumnoid genera for species previously assigned to Planopilumnus Balss, 1933. Zootaxa, 2392(1): 33-61. https://doi.org/10.11646/zootaxa.2392.1.2
https://doi.org/10.11646/zootaxa.2392.1....
). He supported the placement of Planopilumnidae Serène, 1984Serène R 1984. Crustacés Décapodes Brachyoures de l'Océan Indien occidental et de la Mer Rouge. Xanthoidea: Xanthidae et Trapeziidae. Addendum Carpiliidae et Menippidae - A. Crosnier. Faune Tropicale, 24: 1-400. https://decapoda.nhm.org/references/pdfpick.html?id=11789&pdfroot=https://decapoda.nhm.org/pdfs
https://decapoda.nhm.org/references/pdfp...
, in Pseudozioidea Alcock, 1898Alcock A 1898. Materials for a carcinological fauna of India. No. 3. The Brachyura Cyclometopa. Part I. The family Xanthidae. Journal of the Asiatic Society of Bengal, Calcutta, 67(1): 67-233. https://doi.org/10.5962/bhl.title.16033
https://doi.org/10.5962/bhl.title.16033...
(also see Ng et al., 2008Ng PKL; Guinot D and Davie PJF 2008. Systema Brachyurorum: Part I. An annotated checklist of extant brachyuran crabs of the world. Raffles Bulletin of Zoology, Supplement, 17: 1-286. https://lkcnhm.nus.edu.sg/app/uploads/2017/04/s17rbz.pdf
https://lkcnhm.nus.edu.sg/app/uploads/20...
) and established Vellumnus for a group of pilumnid crabs which had been confused with Planopilumnus Balss, 1933. Four Vellumnus species are currently recognised: V. labyrinthicus (Miers, 1884Miers EJ 1884. Crustacea. p. 178-322, pls. 18-32. In: Report on the zoological collections made in the Indo-Pacific Ocean during the voyage of H.M.S. Alert 1881-1882. Part I. The collections from Melanesia. London, British Museum (Natural History). https://doi.org/10.5962/bhl.title.11669
https://doi.org/10.5962/bhl.title.11669...
) (type species), V. minabensis (Sakai, 1969Sakai T 1969. Two new genera and twenty-two new species of crabs from Japan. Proceedings of the Biological Society of Washington, 82: 243-280. https://biostor.org/reference/77888
https://biostor.org/reference/77888...
), V. penicillatus (Gordon, 1930Gordon I 1930. Seven new species of Brachyura from the coasts of China. Annals and Magazine of Natural History, (10)6(34): 519-525. https://doi.org/10.1080/00222933008673240
https://doi.org/10.1080/0022293300867324...
) and V. pygmaeus (Takeda, 1977aTakeda M 1977a. Crabs of the Ogasawara Islands, V. A collection made by dredging. Memoirs of the National Science Museum, Tokyo, 10: 113-140. https://www.kahaku.go.jp/research/publication/zoology/download/10_4/BNSM100403.pdf
https://www.kahaku.go.jp/research/public...
). Ng (2010Ng PKL 2010. On the Planopilumnidae Serène, 1984 (Crustacea: Brachyura: Pseudozioidea), with diagnoses of two new pilumnoid genera for species previously assigned to Planopilumnus Balss, 1933. Zootaxa, 2392(1): 33-61. https://doi.org/10.11646/zootaxa.2392.1.2
https://doi.org/10.11646/zootaxa.2392.1....
) noted that Lazaropilumnus Števčić, 2005Stevčić Z 2005. The reclassification of Brachyuran Crabs (Crustacea: Decapoda: Brachyura). Natura Croatica (Fauna Croatica), 14(1): 1-159. (type species: Planopilumnus minabensis Sakai, 1969) was a nomen nudum as no characters were mentioned in the original description and treated it as a junior synonym of Vellumnus. Lazaropilumnus had previously been listed in the synonymy of PilumnusLeach, 1816Leach WE 1816. A tabular view of the external characters of four classes of animals, which Linné arranged under Insecta; with the distribution of the genera composing three of these classes into orders, &c. and descriptions of several new genera and species. Transactions of the Linnean Society of London, 11(4): 306-400. https://doi.org/10.5962/bhl.title.119762
https://doi.org/10.5962/bhl.title.119762...
, by Ng et al. (2008Ng PKL; Guinot D and Davie PJF 2008. Systema Brachyurorum: Part I. An annotated checklist of extant brachyuran crabs of the world. Raffles Bulletin of Zoology, Supplement, 17: 1-286. https://lkcnhm.nus.edu.sg/app/uploads/2017/04/s17rbz.pdf
https://lkcnhm.nus.edu.sg/app/uploads/20...
).

Vellumnus penicillatus was described from Hong Kong; it is poorly known and has only been reported once since, from Singapore (Balss, 1938Balss H 1938. Ueber einige Xanthidae (Crustacea: Dekapoda) von Singapore und Umgebung. Bulletin of the Raffles Museum, 14: 48-63. https://lkcnhm.nus.edu.sg/app/uploads/2017/06/14brm048-063.pdf
https://lkcnhm.nus.edu.sg/app/uploads/20...
). During a recent visit to the Natural History Museum (NHM), London, the opportunity was taken to re-examine the V. penicillatus type material. In this paper, the types of Gordon’s species are redescribed and a new species is recognised from the Macclesfield Bank, South China Sea.

Material examined is deposited in the NHM and the Zoological Reference Collection (ZRC), Lee Kong Chian Natural History Museum, National University of Singapore. Measurements provided are in millimetres and are of the maximum carapace width and length, respectively. The following abbreviations are used: coll., collected by; G1, male first gonopods and G2, male second gonopod. The terminology used follows Davie et al. (2015Davie PJF; Guinot D and Ng PKL 2015. Anatomy and functional morphology of Brachyura. p. 11-163. In: Castro P; Davie PJF; Guinot D; Schram FR and von Vaupel Klein JC (Eds.), Treatise on Zoology - Anatomy, Taxonomy, Biology. The Crustacea. Volume 9C-I. Decapoda: Brachyura (Part 1). Leiden, Boston, Brill. https://doi.org/10.1163/9789004190832_004
https://doi.org/10.1163/9789004190832_00...
).

TAXONOMY

Family Pilumnidae Samouelle, 1819Samouelle G 1819. The Entomologist's Useful Compendium, or an Introduction to the Knowledge of the British Insects. 496 pp, London, Thomas Boys. https://doi.org/10.5962/bhl.title.34177
https://doi.org/10.5962/bhl.title.34177...

Genus Vellumnus Ng, 2010Ng PKL 2010. On the Planopilumnidae Serène, 1984 (Crustacea: Brachyura: Pseudozioidea), with diagnoses of two new pilumnoid genera for species previously assigned to Planopilumnus Balss, 1933. Zootaxa, 2392(1): 33-61. https://doi.org/10.11646/zootaxa.2392.1.2
https://doi.org/10.11646/zootaxa.2392.1....

Type species. Pilumnus labyrinthicusMiers, 1884Miers EJ 1884. Crustacea. p. 178-322, pls. 18-32. In: Report on the zoological collections made in the Indo-Pacific Ocean during the voyage of H.M.S. Alert 1881-1882. Part I. The collections from Melanesia. London, British Museum (Natural History). https://doi.org/10.5962/bhl.title.11669
https://doi.org/10.5962/bhl.title.11669...
, by original designation.

Remarks. Of the five Vellumnus species originally recognised, Ng (2010Ng PKL 2010. On the Planopilumnidae Serène, 1984 (Crustacea: Brachyura: Pseudozioidea), with diagnoses of two new pilumnoid genera for species previously assigned to Planopilumnus Balss, 1933. Zootaxa, 2392(1): 33-61. https://doi.org/10.11646/zootaxa.2392.1.2
https://doi.org/10.11646/zootaxa.2392.1....
) expressed doubt about the assignment of V. vermiculatus (A. Milne-Edwards, 1873Milne-Edwards A 1873. Recherches sur la faune carcinologique de la Nouvelle-Calédonie, Deuxième Partie. Nouvelles Archives du Muséum d'Histoire naturelle, Paris, 9: 155-332. https://doi.org/10.5962/bhl.title.10410
https://doi.org/10.5962/bhl.title.10410...
) to this genus stating that it may require transferring to LophoplaxTesch, 1918Tesch JJ 1918. Decapoda Brachyura II. Goneplacidae and Pinnotheridae. Siboga Expeditie Monographie, 39c1: 149-295, pls. 7-18.. Examination of type specimens as well as material from the West Pacific were examined and the carapace characters show it is closer to Lophoplax, notably in the hepatic, gastric, and intestinal regions being swollen and setae covering the surfaces around them (see also Maenosono, 2019Maenosono T 2019. Report on nine rare pilumnid crabs (Crustacea: Decapoda: Brachyura) collected from southern Japan, including three new records. Fauna Ryukyuana, 48: 19-44. [In Japanese with English abstract] https://www.researchgate.net/publication/340629602_Report_on_nine_rare_pilumnid_crabs_Crustacea_Decapoda_Brachyura_collected_from_southern_Japan_including_three_new_records_In_Japanese_with_English_abstract
https://www.researchgate.net/publication...
; Trivedi et al., 2022Trivedi JK; Patel K, Mitra S and Ng PKL 2022. On the identity of Myopilumnus andamanicus Deb, 1989 (Crustacea: Decapoda: Brachyura: Pilumnidae) from India. Zootaxa , 5194(4): 595-600. https://doi.org/10.11646/zootaxa.5194.4.8
https://doi.org/10.11646/zootaxa.5194.4....
). It has since been transferred to this genus (Ng and Rahayu, 2023Ng PKL and Rahayu DL 2023. Review of the pilumnid crab genus Lophoplax Tesch, 1918 from the western Pacific, with descriptions of two new species, and the clarification of the identity of Pseudocryptocoeloma parvus Ward, 1936 (Crustacea: Brachyura). Zootaxa, 5244(5): 428-454. https://doi.org/10.11646/zootaxa.5244.5.2
https://doi.org/10.11646/zootaxa.5244.5....
).

Vellumnus penicillatus ( Gordon, 1930Gordon I 1930. Seven new species of Brachyura from the coasts of China. Annals and Magazine of Natural History, (10)6(34): 519-525. https://doi.org/10.1080/00222933008673240
https://doi.org/10.1080/0022293300867324...
)

(Figs. 1-3)

Figure 1.
Vellumnus penicillatus (Gordon, 1930). A, Holotype female (4.2 × 2.9 mm) (NHM 1930.12.2.123), Hong Kong; B, C, paratype male (3.6 × 2.9 mm) (NHM 1930.12.2.124), Hong Kong. A, B, overall dorsal view; C, ventral view of cephalothorax.

Figure 2.
Vellumnus penicillatus (Gordon, 1930). A, B, Paratype male (3.6 × 2.9 mm) (NHM 1930.12.2.124), Hong Kong; C, paratype ovigerous female (5.3 × 3.7 mm) (NHM 1030.12.2.124), Hong Kong. A, outer view of chelae; B, dorsal view of right cheliped; C, overall dorsal view.

Figure 3.
Vellumnus penicillatus (Gordon, 1930). A, B, Holotype female (4.2 × 2.9 mm) (NHM 1930.12.2.123), Hong Kong; C-I, paratype male (3.6 × 2.9 mm) (NHM 1930.12.2.124), Hong Kong. A, Carapace (after Gordon, 1931Gordon I 1931. Brachyura from the coasts of China. Journal of the Linnean Society, Zoology, 37(254): 525-558. https://doi.org/10.1111/j.1096-3642.1931.tb02365.x
https://doi.org/10.1111/j.1096-3642.1931...
: text-fig. 18a); B, left side of denuded carapace; C, right side of denuded carapace; D, posterior margin of epistome; E, left third maxilliped (denuded); F, anterior thoracic sternum; G, pleon; H, right G1 (dorsal view); I, right G1 (ventral view); J, right G2. Scales: B-G = 0.5 mm; H-J = 0.2 mm.

Pilumnus penicillatusGordon, 1930Gordon I 1930. Seven new species of Brachyura from the coasts of China. Annals and Magazine of Natural History, (10)6(34): 519-525. https://doi.org/10.1080/00222933008673240
https://doi.org/10.1080/0022293300867324...
: 523. - Gordon, 1931Gordon I 1931. Brachyura from the coasts of China. Journal of the Linnean Society, Zoology, 37(254): 525-558. https://doi.org/10.1111/j.1096-3642.1931.tb02365.x
https://doi.org/10.1111/j.1096-3642.1931...
: 542, fig. 18. - Balss, 1933Balss H 1933. Beitrage zur kenntnis Gattung Pilumnus und verwandter Gattungen. Capita Zoologica, 4(3): 1-47.: 12.

Pilumnuspenicillatus - Ng et al., 2008Ng PKL; Guinot D and Davie PJF 2008. Systema Brachyurorum: Part I. An annotated checklist of extant brachyuran crabs of the world. Raffles Bulletin of Zoology, Supplement, 17: 1-286. https://lkcnhm.nus.edu.sg/app/uploads/2017/04/s17rbz.pdf
https://lkcnhm.nus.edu.sg/app/uploads/20...
: 142, 145.

Material examined. Holotype female (4.2 × 2.9 mm) (NHM 1930.12.2.123), Hong Kong, Barney collection. Paratypes: male (3.6 × 2.9 mm) (NHM 1930.12.2.124), ovigerous female (5.3 × 3.7 mm) (NHM 1030.12.2.124), same data as holotype.

Diagnosis. Carapace hexagonal, wide; surface and pereiopods covered with dense, short, soft pubescence as well as scattered long plumose setae completely obscuring margins and surfaces, longer setae arranged in clumps on carapace regions, forming faint circular patterns on gastric regions (Figs. 1A, B, 2C, 3A); epigastric, mesogastric, postorbital cristae low, gastric, subhepatic, branchial regions with scattered low granules (Figs. 1A, B, 2C, 3A); frontal margin gently convex to sinuous, lateral lobe low but distinct; supraorbital margin with prominent median fissure (Fig. 3A-C); external orbital tooth triangular, subtruncate, first anterolateral tooth triangular or bilobed, third tooth smallest (Fig. 3A-C); anteroexternal angle of merus of third maxilliped distinct but not auriculiform, ischium with shallow oblique sulcus (Fig. 3E); outer surface of chelae with numerous round granules, vaguely arranged in longitudinal rows, carpus with numerous round granules, without distinct tooth on inner angle, fingers shorter than palm (Fig. 2A, B); ambulatory legs without distinct crests or ridges; surfaces completely obscured by numerous setae (Figs. 1A-C); anterior thoracic sternum with surfaces relatively smooth, no trace of separation between sternites 3 and 4 except for lateral sutures (Figs. 1C, 3F); tubercle of sterno-pleonal locking mechanism round, on anterior third of sternite 5 (Fig. 3F); male pleon relatively narrow; somite subrectangular, somites 1, 3 subequal in width, telson semicircular (Figs. 1C, 3G); G1 slender, sinuous, distal part bent laterally with sharp tip (Fig. 3H, I).

Distribution. Hong Kong (Gordon, 1930Gordon I 1930. Seven new species of Brachyura from the coasts of China. Annals and Magazine of Natural History, (10)6(34): 519-525. https://doi.org/10.1080/00222933008673240
https://doi.org/10.1080/0022293300867324...
).

Remarks. Vellumnus penicillatus is here described in detail with additional figures. The dorsal surface of the carapace comprises dense setae arranged in approximate patterns (Figs. 2C, 3A) but is without underlying ridges, the surface is generally smooth with only scattered granules on the lateral parts (Fig. 1A, B).

Takeda (1977aTakeda M 1977a. Crabs of the Ogasawara Islands, V. A collection made by dredging. Memoirs of the National Science Museum, Tokyo, 10: 113-140. https://www.kahaku.go.jp/research/publication/zoology/download/10_4/BNSM100403.pdf
https://www.kahaku.go.jp/research/public...
: 131) listed a number of characters that distinguished V. penicillatus from V. pygmaeus (type locality: Ogasawara Islands): “the median gastric region is indicated by a longitudinal strand ending in a diamond, a tomentum on each protogastric region forms a circle or ocellus, the areolation beneath the tomentum is only faintly indicated, the carapace is apparently broader with the nearly truncated second and third anterolateral teeth, the latter of which forms the lateral angle of the carapace, and the male first pleopod bears a strong subdistal spine.” His carapace setal patterns, however, do not appear to be a good character because the original figure by Gordon (1931Gordon I 1931. Brachyura from the coasts of China. Journal of the Linnean Society, Zoology, 37(254): 525-558. https://doi.org/10.1111/j.1096-3642.1931.tb02365.x
https://doi.org/10.1111/j.1096-3642.1931...
) is somewhat schematic (present Fig. 3A). The two species, however, are different; in V. penicillatus, the supraorbital and anterolateral margins are relatively longer; Fig. 3A-C (vs. supraorbital and anterolateral margins shorter in V. pygmaeus; Takeda, 1977aTakeda M 1977a. Crabs of the Ogasawara Islands, V. A collection made by dredging. Memoirs of the National Science Museum, Tokyo, 10: 113-140. https://www.kahaku.go.jp/research/publication/zoology/download/10_4/BNSM100403.pdf
https://www.kahaku.go.jp/research/public...
: fig. 5A); the hepatic region and surfaces behind the anterolateral teeth are not swollen, at most with a few granules; Fig. 3A-C (vs. hepatic region with a prominent swelling posterior to the first anterolateral tooth in V. pygmaeus; Takeda, 1977aTakeda M 1977a. Crabs of the Ogasawara Islands, V. A collection made by dredging. Memoirs of the National Science Museum, Tokyo, 10: 113-140. https://www.kahaku.go.jp/research/publication/zoology/download/10_4/BNSM100403.pdf
https://www.kahaku.go.jp/research/public...
: fig. 5A); and the G1 is more slender and sinuous with the distal part proportionately longer and more distinctly tapering; Fig. 3H, I (vs. stouter and less sinuous with the distal part shorter in V. pygmaeus; Takeda, 1977aTakeda M 1977a. Crabs of the Ogasawara Islands, V. A collection made by dredging. Memoirs of the National Science Museum, Tokyo, 10: 113-140. https://www.kahaku.go.jp/research/publication/zoology/download/10_4/BNSM100403.pdf
https://www.kahaku.go.jp/research/public...
: fig. 5B, C).

The specimen from Singapore reported as “Planopilumnus penicillatus” by Balss (1938Balss H 1938. Ueber einige Xanthidae (Crustacea: Dekapoda) von Singapore und Umgebung. Bulletin of the Raffles Museum, 14: 48-63. https://lkcnhm.nus.edu.sg/app/uploads/2017/06/14brm048-063.pdf
https://lkcnhm.nus.edu.sg/app/uploads/20...
: 60) and “Vellumnus penicillatus” by Ng (2010Ng PKL 2010. On the Planopilumnidae Serène, 1984 (Crustacea: Brachyura: Pseudozioidea), with diagnoses of two new pilumnoid genera for species previously assigned to Planopilumnus Balss, 1933. Zootaxa, 2392(1): 33-61. https://doi.org/10.11646/zootaxa.2392.1.2
https://doi.org/10.11646/zootaxa.2392.1....
: 51) is not this species. This specimen was re-examined. It appears to be a male in poor condition, being damaged and extremely soft with all the appendages detached. It seems to be a young V. labyrinthicus. As such, V. penicillatus s. str. remains restricted to Hong Kong.

Vellumnus tki n. sp.

(Figs. 4-6)

Zoobank: urn:lsid:zoobank.org:pub:31ABBD35-9781-4D92-82E7-A3BCF8BB61BF

Figure 4.
Vellumnus tki n. sp., holotype male (7.8 × 6.0 mm) (NHM 1932.7.7.22), Macclesfield Bank. A, Overall dorsal view; B, ventral view of cephalothorax

Figure 5.
Vellumnus tki n. sp., holotype male (7.8 × 6.0 mm) (NHM 1932.7.7.22), Macclesfield Bank. A, Dorsal view of carapace (right side denuded); B, outer view of left chela; C, dorsal view of left cheliped; D, left fourth ambulatory leg.

Figure 6.
Vellumnus tki n. sp., holotype male (7.8 × 6.0 mm) (NHM 1932.7.7.22), Macclesfield Bank. A, Right side of denuded carapace; B, front, epistome, antennule, antenna and orbit; C, left third maxilliped (denuded); D, left fourth ambulatory leg (denuded); E, anterior thoracic sternum; F, pleon; G, left G1 (ventral view); H, distal part of left G1 (ventral view); I, tip of left G1 (ventral view); J, distal part of left G1 (dorsal view); K, left G2. Scales: A-F= 1.0 mm; G, J = 0.5 mm; H, I = 0.2 mm.

Material examined. Holotype: male (7.8 × 6.0 mm) (NHM 1932.7.7.22, ex 1893.11.3), Macclesfield Bank, South China Sea, coll. P.W. Bassett-Smith, 1893.

Diagnosis. Carapace relatively quadrate (Figs. 4A, 5A); setae on carapace evenly distributed, without ridges or vermiform patterns (Figs. 4A, 5A); setae on pereiopods covered with dense, short, soft pubescence almost completely obscuring margins and surfaces (Figs. 4A, 5A); epigastric, mesogastric, postorbital cristae low, gastric, subhepatic and branchial regions with on anterior margins (Figs. 5A, 6A); frontal margin convex, lateral lobe distinct, bilobed; supraorbital margin with distinct median fissure (Figs. 5A, 6A); external orbital tooth acutely triangular, anterolateral teeth relatively smaller, triangular, third tooth smallest, margins lined with small granules (Figs. 5A, 6A); anteroexternal angle of merus of third maxilliped angular but not auriculiform, ischium with shallow oblique sulcus (Fig. 6C); outer surface of chelae with numerous round granules, vaguely arranged in longitudinal rows, carpus with numerous round granules, without distinct tooth on inner angle, fingers shorter than palm (Figs. 4A, B, 5B, C); ambulatory legs relatively short, without distinct crests or ridges; surfaces completely obscured by numerous setae (Figs. 4A, B, 5D); anterior thoracic sternum with surfaces relatively smooth, sternites 3, 4 fused with shallow groove and lateral sutures demarcating them (Figs. 4B, 6E); tubercle of sterno-pleonal locking mechanism rounded, on submedian part of sternite 5 (Fig. 3F); male pleon relatively narrow; somite subrectangular, somites 1 and 3 subequal in width, telson subtriangular (Figs. 4B, 6F); G1 slender, sinuous, distal part bent laterally with subtruncate tip forming small flap on dorsal part (Fig. 6H-I).

Etymology. This species is named for the High Commissioner of the Republic of Singapore, London, in gratitude for all his support of the natural history digital repatriation project between the Lee Kong Chian Natural History Museum, Singapore, and the Natural History Museum, London. His Excellency Lim Thuan Kuan is known as “TK” to his friends (pronounced “tee-kay”), and is the origin of “tki”.

Remarks. The holotype was examined by Heinrich Balss in June 1932 and identified as “?Lophoplax(Pilumnoplax) sculpta”, but it is not this pilumnid species (see Takeda, 1977bTakeda M 1977b. Rediscovery of Lophoplax sculpta (Stimpson, 1858) (Crustacea, Decapoda, Brachyura). Zoological Magazine, 86: 120-123. ; Maenosono, 2019Maenosono T 2019. Report on nine rare pilumnid crabs (Crustacea: Decapoda: Brachyura) collected from southern Japan, including three new records. Fauna Ryukyuana, 48: 19-44. [In Japanese with English abstract] https://www.researchgate.net/publication/340629602_Report_on_nine_rare_pilumnid_crabs_Crustacea_Decapoda_Brachyura_collected_from_southern_Japan_including_three_new_records_In_Japanese_with_English_abstract
https://www.researchgate.net/publication...
; Ng and Rahayu, 2023Ng PKL and Rahayu DL 2023. Review of the pilumnid crab genus Lophoplax Tesch, 1918 from the western Pacific, with descriptions of two new species, and the clarification of the identity of Pseudocryptocoeloma parvus Ward, 1936 (Crustacea: Brachyura). Zootaxa, 5244(5): 428-454. https://doi.org/10.11646/zootaxa.5244.5.2
https://doi.org/10.11646/zootaxa.5244.5....
). Instead, it is considered here to be an undescribed Vellumnus species.

In the relatively larger size, (ca. carapace width > 4-5 mm), a more quadrate shaped carapace, distinct carapace areolation, e.g., regions well demarcated, and relatively wider male anterior thoracic sternum, Vellumnus tki n. sp. is most similar to V. minabensis, but differs in that the carapace is more quadrate in shape, e.g., width to length ratio 1.30; Figs. 4A, 5A (vs. carapace proportionately wider, e.g., width to length ratio 1.4 in V. minabensis); the frontal lobe is convex; Figs. 5A, 6A (vs. frontal lobe strongly convex in V. minabensis); the regions of carapace have scattered granules only on the anterior margins; Figs. 5A, 6A (vs. regions of carapace covered with numerous granules in V. minabensis); the anterolateral teeth are proportionately smaller; Figs. 5A, 6A (vs. anterolateral teeth large and prominent in V. minabensis); the granules on the carpus and chela are distinctly more dispersed; Fig. 5B, C (vs. granules on the carpus and chela densely packed in V. minabensis); and the ambulatory merus appears to be relatively shorter; Figs. 4A, 5D (vs. ambulatory merus relatively longer in V. minabensis; cf. Sakai, 1969Sakai T 1969. Two new genera and twenty-two new species of crabs from Japan. Proceedings of the Biological Society of Washington, 82: 243-280. https://biostor.org/reference/77888
https://biostor.org/reference/77888...
: text-fig. 13; Sakai, 1976Sakai T 1976. Crabs of Japan and the Adjacent Seas. In three volumes; English Text, xxix+773p., Japanese Text, p. 1-461, Plates volume, p. 1-16, pls. 1-251. Tokyo, Kodansha Ltd.: text fig. 263, pl. 176, fig. 1). The G1 structures of the two species are similar, with the distal part slightly shorter with the tip more truncate in V. tki n. sp.; Fig. 6G-I (vs. longer and more tapering in V. minabensis; Sakai, 1969Sakai T 1976. Crabs of Japan and the Adjacent Seas. In three volumes; English Text, xxix+773p., Japanese Text, p. 1-461, Plates volume, p. 1-16, pls. 1-251. Tokyo, Kodansha Ltd.: text-fig. 12a) but this difference is not significant at the species level. The arrangement of setae on the carapace of V. tki n. sp. is also different from that of V. minabensis. Sakai (1969Sakai T 1976. Crabs of Japan and the Adjacent Seas. In three volumes; English Text, xxix+773p., Japanese Text, p. 1-461, Plates volume, p. 1-16, pls. 1-251. Tokyo, Kodansha Ltd.) described the setae on the carapace of V. minabensis as arranged in a “vermiform” manner (Sakai, 1969Sakai T 1976. Crabs of Japan and the Adjacent Seas. In three volumes; English Text, xxix+773p., Japanese Text, p. 1-461, Plates volume, p. 1-16, pls. 1-251. Tokyo, Kodansha Ltd.: 266) but his original figure (Sakai, 1969Sakai T 1976. Crabs of Japan and the Adjacent Seas. In three volumes; English Text, xxix+773p., Japanese Text, p. 1-461, Plates volume, p. 1-16, pls. 1-251. Tokyo, Kodansha Ltd.: text-fig. 13) does not illustrate this character. In a later color figure of the species, however, he showed the vermiform setal patten (Sakai, 1976Sakai T 1976. Crabs of Japan and the Adjacent Seas. In three volumes; English Text, xxix+773p., Japanese Text, p. 1-461, Plates volume, p. 1-16, pls. 1-251. Tokyo, Kodansha Ltd.: pl. 176 fig. 1). This carapace setation pattern resembles that of V. labyrinthicus except that in V. minabensis, the carapace is proportionately wider and the anterolateral teeth are relatively weaker and directed obliquely anteriorly (Sakai, 1969Sakai T 1976. Crabs of Japan and the Adjacent Seas. In three volumes; English Text, xxix+773p., Japanese Text, p. 1-461, Plates volume, p. 1-16, pls. 1-251. Tokyo, Kodansha Ltd.: fig. 13; Sakai, 1976Sakai T 1976. Crabs of Japan and the Adjacent Seas. In three volumes; English Text, xxix+773p., Japanese Text, p. 1-461, Plates volume, p. 1-16, pls. 1-251. Tokyo, Kodansha Ltd.: text fig. 263, pl. 176, fig. 1) (vs. carapace more quadrate, with the anterolateral teeth stronger and directed more laterally; cf. Ng, 2010Ng PKL 2010. On the Planopilumnidae Serène, 1984 (Crustacea: Brachyura: Pseudozioidea), with diagnoses of two new pilumnoid genera for species previously assigned to Planopilumnus Balss, 1933. Zootaxa, 2392(1): 33-61. https://doi.org/10.11646/zootaxa.2392.1.2
https://doi.org/10.11646/zootaxa.2392.1....
: figs. 13A, 14A, 15A). The setae on the carapace of V. tki n. sp. are evenly distributed (Figs. 4A, 5A) and there are no ridges or vermiform patterns formed.

ACKNOWLEDGEMENTS

Thanks are due to Miranda Lowe (NHM) for curatorial support.

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Additional Information and Declarations

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Edited by

Associate Editor:

Dr. Marcos Tavares

Data availability

Not applicable.

Publication Dates

  • Publication in this collection
    22 May 2023
  • Date of issue
    2023

History

  • Received
    09 July 2022
  • Accepted
    20 Dec 2022
Sociedade Brasileira de Carcinologia Instituto de Biociências, UNESP, Campus Botucatu, Rua Professor Doutor Antônio Celso Wagner Zanin, 250 , Botucatu, SP, 18618-689 - Botucatu - SP - Brazil
E-mail: editor.nauplius@gmail.com