Pele, Ng, Peter K. L., 2011

Ng, Peter K. L., 2011, Pele ramseyi, a new genus and new species of anchialine swimming crab (Crustacea: Brachyura: Portunidae) from the Hawaiian Islands, Zootaxa 2737, pp. 34-48 : 34-37

Pele , new genus

Type species. Pele ramseyi new species, by present designation.

Diagnosis. Carapace transversely ovate; dorsal surface smooth, without ridges, regions poorly defined ( Figs. 2 C, 3A, 4A, 5, 7A). Orbits small; eye barely mobile, eyestalk, cornea reduced; cornea weakly pigmented ( Fig. 7 A–C). Anterolateral margin arcuate, lined with small granules, with 4 or 5 larger tubercles; external orbital angle low ( Fig. 5 , 7 A). Basal antennal segment subquadrate, surface unarmed, outer margin completely closing orbital hiatus; flagellum long, excluded from orbital hiatus ( Figs. 4 B, C, 7B). Posterior margin of epistome with bilobed median projection ( Figs. 4 B, 7B). Endostomial ridges distinct ( Fig. 7 B). Merus of third maxilliped with weakly produced, rounded antero-external angle ( Figs. 4 C, 7D). Male chelipeds asymmetrical ( Figs. 4 A, 3B, 6B, C); merus elongated, with sharp subdistal spine ( Figs. 3 A, 4A, 8A); minor male and female chelae with long forceps-like fingers, cutting margins with about 7 sharp spiniform teeth on propodus, dactylus unarmed ( Fig. 6 C). Ambulatory legs elongated, smooth, unarmed; dactylus of last leg almost straight ( Figs. 3 A, 4A, 8B). Thoracic sternum relatively broad ( Figs. 6 A, 7E, F); sternites 1, 2 completely fused, suture between sternites 2, 3 distinct, gently convex anteriorly; sternites 3, 4 fused; sutures between sternites 4–8 all medially interrupted ( Figs. 6 A, 7E, F); male abdominal locking press-button on posterior margin of sternite 5, peg-like ( Fig. 7 E, G). Penis coxal, relatively long, sits in submedian transverse groove on sternite 8 ( Figs. 6 A, 7F). Sternoabdominal cavity reaching to thoracic sternite 3 ( Figs. 6 A, 7E). Male abdomen T-shaped, somites 3-5 completely fused; telson linguiform, 2 times longer than broad ( Fig. 8 C). G1 with relatively broader basal part which bends sinuously upwards to form slender, straight distal half; tip tapering sharply ( Figs. 6 A, 8D, E). G2 short, approximately one-third G1 length ( Fig. 8 F).

Etymology. The genus is named after Pele , the Goddess of Fire and a Hawaiian Volcano Goddess. She was also killed in Maui, the type locality of the type species, P. ramseyi . The name is used as a noun in the nominative singular. Gender feminine.

Remarks. In the general form of the carapace, chelipeds and ambulatory legs, Pele new genus resembles the carupine Libystes A. Milne-Edwards, 1867 . Pele new genus, however, can easily be separated by its much broader transversely ovate carapace ( Figs. 2 A, 3A, 4A, 5, 7A) (transversely subquadrate or subovate in Libystes , cf. A. Milne-Edwards 1868: pl. 20 fig. 5; Edmondson 1951: fig. 25a; Stephenson & Campbell 1960: pl. 1 fig. 4; Crosnier 1962: fig. 5; Miyake & Takeda 1970: figs. 1, 3; Apel & Spiridinov 1998: figs. 5a, 6a; Vannini & Innocenti 2000: fig. 90); the orbits are small, with the eye barely movable, and the eyestalk and cornea distinctly reduced and not filling the orbits ( Fig. 4 B, C, 7B, C) (orbits normal size, with mobile and well-developed eyestalks and corneas that fill the orbits in Libystes , cf. A. Milne-Edwards 1868: pl. 20 fig. 6; Edmondson 1951: fig. 25a; Crosnier 1962: figs. 5, 6; Apel & Spiridinov 1998: figs. 5a, 6a; Vannini & Innocenti 2000: fig. 90); the anteroexternal angle of the merus of the third maxilliped is slightly produced and rounded but not prominently auriculiform ( Figs. 4 C, 7D) (prominently auriculiform in Libystes , cf. Crosnier 1962: fig. 7; Miyake & Takeda 1970: fig. 2A); the merus of the cheliped is elongated, with a prominent subdistal spine on the anterior margin ( Figs. 3 A, 4A, 8A) (relatively shorter, unarmed in Libystes , cf. Stephenson & Campbell 1960: pl. 1 fig. 4; Miyake & Takeda 1970: figs. 1, 3; Apel & Spiridinov 1998: figs. 5b, 6b; Vannini & Innocenti 2000: fig. 90); the male telson is elongated and linguiform, being twice longer than broad ( Fig. 8 C) (triangular, relatively short, length and width subequal or slightly longer in Libystes , cf. Edmondson 1951: fig. 25e; Stephensen 1946: fig. 45C; Miyake & Takeda 1970: fig. 2D); and the G1 sharply bends medially, from a stout base to a long, straight and slender distal part ( Figs. 6 A, 8D, E) (short, stout or C-shaped with distal part tapering gradually in Libystes , cf. Stephensen 1946: fig. 45DC; Stephenson & Campbell 1960: fig. 1B; Serène 1966: figs. 1–6; Apel & Spiridonov 1998: fig. 6d, e; Vannini & Innocenti 2000: fig. 7).

Three other differences merit mention. The ambulatory legs of Pele , new genus, are elongated and slender, proportionately much longer than those of any known Libystes species; and the dactylus of the last ambulatory leg is also almost straight ( Figs. 3 A, 4A, 8B), not distinctly upcurved or paddle-like (cf. A. Milne-Edwards 1868: pl. 20 fig. 5; Edmondson 1951: fig. 25e; Stephenson & Campbell 1960: pl. 1 fig. 4; Crosnier 1962: fig. 10; Miyake & Takeda 1970: figs. 1, 3; Apel & Spiridonov 1998: fig. 6c; Vannini & Innocenti 2000: fig. 90). With regard to the cheliped fingers, the cutting margins in Libystes species usually have triangular teeth and denticles (see A. Milne- Edwards 1868: pl. 20 fig. 7; Edmondson 1951: fig. 25b, c; Crosnier 1962: fig. 9; Miyake & Takeda 1970: fig. 2B, E), although those on the minor chela are sometimes more slender and spiniform teeth are only present on the pollex like in Pele new genus (present material). In Pele new genus, however, the cutting margin of the minor dactylus is almost smooth while that in Libystes is denticulate. The structure and length of the fingers of the minor chela of the male and both chelae of the female of Pele new genus superficially resemble those of some portunids like Atoportunus Ng & Takeda, 2003 (Portuninae) . In Pele new genus, however, the spiniform teeth are restricted to the cutting margin of the pollex ( Fig. 6 C), that of the dactylus been unarmed. In Atoportunus , both margins are armed with similar spiniform teeth (Ng & Takeda 2003: figs. 5B, 7).

Libystes is currently contains six species: Libystes edwardsi Alcock, 1900 ; L. lepidus Miyake & Takeda, 1970 ; L. nitidus A. Milne-Edwards, 1867 (type species by monotypy), L. paucidentatus Stephenson & Campbell, 1960 ; L. vietnamensis Tien, 1969 ; and L. villosus Rathbun, 1924 (Ng et al. 2008) , all of which are Indo-West Pacific in distribution. The genus and type species, L. nitidus , was described by A. Milne-Edwards (1867: 285) on the basis of one specimen (sex not specified) measuring 24 × 15 mm from Zanzibar (see also A. Milne-Edwards 1868: pl. 20 figs. 5–7). Crosnier (1962: 148) re-examined the specimen and noted it was female measuring 22 mm in carapace width. Some authors (e.g. Barnard 1954; Serène 1966; Vannini & Innocenti 2000) synonymised Libystes villosus Rathbun, 1924 (described from a single female from Samoa) with L. nitidus , but others have regarded them as separate species or probably so (e.g. Miyake & Takeda 1970; Apel & Spiridonov 1998). Ng et al. (2008: 155) commented that in view of their different G1s, they should be regarded as separate species for the time being. Similarly, L. alphonsi (described from India) has been questionably synonymised with L. nitidus by Tesch (1918) and Edmondson (1951, 1954), and this has been followed by later workers (e.g. Apel & Spiridinov 1998; Ng et al. 2008). It may be a distinct taxon, with Serène (1966: 994) commenting that he had briefly examined the type of L. alphonsi in the Indian Museum, observed that the differences noted by Alcock (1900) were accurate and that the two species should be regarded as separate. Alcock (1900: 307) wrote “This species [ L. alphonsi ] differs but little, except in the sub-quadrilateral shape of the thorax, from the Libystes nitidus described and figured by M. A. Milne·Edwards”. As such, it is best to retain L. alphonsi as a distinct species for the time being as well. Libystes lepidus was described from the Ogasawara Is., Japan by Miyake & Takeda (1970). The identity of L. vietnamensis Tien, 1969 , is problematic as it was described from two juvenile females measuring only 3 mm in carapace length collected from the Gulf of Tonkin. On the basis of the figures of the carapace, third maxilliped, chelae and last ambulatory leg ( Tien 1969: fig. 1.1–1.4), it appears to be affiliated with L. edwardsi but because the types are juveniles, nothing much else can be said..

Some authors have regarded Libystes and Catoptrus A. Milne-Edwards, 1870 , as synonymous (see Tesch 1918; Stephenson & Campbell 1960; Crosnier 1962; Vannini & Innocenti 2000) but they are clearly distinct genera (see Edmondson 1951, 1954; Serène 1966). The carapace of Libystes is laterally subquadrate (more laterally ovate or rounded in Catoptrus ), the merus of the chelipeds are unarmed (armed with two spines or teeth on in the anterior margin in all species of Catoptrus except C. inaequalis (Rathbun, 1906) and C. quinquedentatus Yang, Chen & Tang, 2006 , and the dactylus of the last ambulatory leg is slender and gently upcurved or paddle-like (straight to lanceolate in Catoptrus ).

Apel & Spiridinov (1998: 179) reviewed the genus Libystes and commented that the taxonomy of the genus was still unsettled. There appears to be at least two species in what is now called “ L. nitidus ”, one with a short and stout G1 (see Stephensen 1946: fig. 45D; Serène 1966: figs. 1–4; Apel & Spiridinov 1998: fig. 6d, e; Vannini & Innocenti 2000: fig. 7) and another with a very slender and elongated G1 ( Edmondson 1951: fig. 25f; Crosnier 1962: 252; Serène 1966: figs. 5, 6). The former type is only known from the Indian Ocean while the latter occurs across the Indo-West Pacific. Four different taxa –( L. nitidus s. str., L. alphonsi , L. villosus and L. lepidus ) need to be examined in regards to the structures of their G1. These species have subovate carapaces with the anterolateral margins entire or weakly denticulated, and the dactylus of the last ambulatory leg is slender and not paddle-like (cf. A. Milne-Edwards 1868: pl. 20 fig. 5; Edmondson 1951: fig. 25e; Crosnier 1962: fig. 10; Miyake & Takeda 1970: figs. 1, 2E, F; Apel & Spiridinov 1998: fig. 6a, c).

There is another group of species of Libystes ( L. edwardsi , L. paucidentatus and probably L. vietnamensis ) which has a subquadrate carapace, the anterolateral margin possesses distinct teeth, the dactylus of the last ambulatory leg is distinctly paddle-like, and the G1 is slender and elongated ( Stephenson & Campbell 1960: fig. 1B; Apel & Spiridinov 1998: fig. 5a). While superficially closer to species of Catoptrus , their carapace structures are distinctly more quadrate (rather than rounded), their G1s are relatively more slender and the last ambulatory dactylus is normal or lanceloate, not paddle-like. These species may require their own genus.

Schweitzer et al. (2003) had synonymised the fossil Carcinoplacoides flottei Kesling, 1958 , from Guam with Libystes nitidus , but in view of the G1 differences between L. nitidus and L. villosus , it may be more logical to place Carcinoplacoides flottei as a synonym of L. villosus for the time being. In any case, a revision of this genus is now in progress (author with T. Naruse).

There are several lots of Libystes in the ZRC, most of which had been examined and figured by Serène (1966). Serène (1966) did not list the material of Libystes he examined and while he stated the size of the specimens for the G1s he figured, he did not indicate their provenance. Fortunately, these can be matched against the ZRC specimens. One specimen of L. edwardsi (ZRC 2000.840) matches the type descriptions very well and was obtained from near one of the type localities in the Andaman Is. Other two specimens identified as “ L. edwardsi ” from Vietnam (ZRC 1970.1.7.32-33) are unlikely to belong to that species, differing also from the Australian L. paucidentatus , and may represent an undescribed species. A series of specimens from the Philippines (ZRC 1967.11.19.7-11) agree well with most of the African accounts of L. nitidus , including the type, in having an anterolateral margin which is barely denticulated and almost entire, with a slender and sinuous G1 (see Serène 1966: figs. 5, 6). There is also a good series of specimens from Vietnam (ZRC 1970.1.7.26-31) that is composed of two species. Four specimens (ZRC 1970.1.7.26-29) superficially resemble L. lepidus but differ markedly in having low but distinct anterolateral teeth (but much less developed compared to L. edwardsi ) (becoming lower and less conspicuous in larger specimens) but have a slender upcurved last ambulatory dactylus, and the G1 is short and stout (see Serène 1966: figs. 1, 2). Two specimens (ZRC 1970.1.7.30-31) are unusual in that their anterolateral margin is entire with no trace of denticles or teeth. In all respects, including in their more setose chelipeds and ambulatory legs, they agree very well with what has been described as L. villosus (see also Miyake & Takeda 1970: fig. 3) but its G1 is relatively stout, as figured by Serène (1966: figs. 3, 4), differing substantially with what was figured for this species by Edmondson (1951: fig. 25f). It is clear that Serène (1966: figs. 1–6) treated this material from the Philippines and Vietnam as conspecific, interpreting the G1 differences as age- and size-related. However, in view of the differences in carapace, cheliped and ambulatory leg characters observed at present for both sexes of various sizes, it is more likely that we are dealing with three separate species here. The identities of these species will need to be resolved later when the genus is revised.

Comparative material. Libystes nitidus : holotype female (22.00 × 15.00 mm) ( MNHN 2039), Zanzibar, coll. M. Garndidier (photographs only); 4 males (11.26 × 6.44 mm, 7.73 × 4.67 mm, 7.28 × 4.31 mm, 4.99 × 8.05 mm), 1 female (9.12 × 5.43 mm) ( ZRC 1967.11.19.7-11), Datagatangan Lab., Philippines, coll. Fisheries Department, 1966. Libystes aff. lepidus : 2 males (11.40 × 6.90 mm, 9.30 × 6.90 mm), 1 ovigerous female (11.50 × 7.20 mm) ( NSMT 5529), station 17, Ogasawara Islands, 42m, coll. M. Takeda & M. Imajima, 16 June 1976. Libystes aff. lepidus : 1 male (5.02 × 2.98 mm), 3 females (9.00 × 5.51 mm, 8.99 × 5.93 mm, 8.08 × 5.10 mm) ( ZRC 1970.1.7.26- 29), Nhatrang, Vietnam, coll. NAGA Expedition, 1958. Libystes villosus : 1 male (dismembered, poorly preserved) (6.5 × 4.0 mm), 6 females (largest 12.4 × 7.7 mm) ( NSMT 7023), Chichi-jima, Ogasawara Islands, coll. Y. Kurata, no date. Libystes aff. villosus : 1 male (7.02 × 4.06 mm), 1 female (11.12 × 6.55 mm) ( ZRC 1970.1.7.30-31), Nhatrang, Vietnam, coll. NAGA Expedition, 1958. Libystes edwardsi : 1 male (12.33 × 6.99 mm) ( ZRC 2000.840), Pichai fish port, from trawlers in Andaman Sea, western Thailand, coll. P. K. L. Ng, 3-6 May 2000. Libystes aff. edwardsi : 2 males (7.66 × 4.51 mm, other damaged and dismembered), station 831, Nhatrang, Vietnam, coll. NAGA Expedition, 1958.

Figures

FIGURE 2. Pele ramseyi new genus, new species, colours in life. A, B, specimens of Pele ramseyi, new genus, new species, in situ in anchialine pools (specimens not caught); C, paratype female (11.53 × 6.14 mm) (ZRC 2010.0322). (Photographs: M. Ramsey)

FIGURE 3. Pele ramseyi new genus, new species, colours in life. A, C, paratype female (11.53 × 6.14 mm) (ZRC 2010.0322); B, holotype male (9.32 × 4.99 mm) (BPBM S 15980). (Photographs: M. Ramsey)

FIGURE 4. Pele ramseyi new genus, new species, holotype male (9.32 × 4.99 mm) (BPBM S 15980). A, overall dorsal view; B, frontal view of carapace; C, frontal view of carapace showing mouthparts.

FIGURE 5. Pele ramseyi new genus, new species, dorsal views of carapaces. A, holotype male (9.32 × 4.99 mm) (BPBM S 15980); B, paratype female (11.53 × 6.14 mm) (ZRC 2010.0322).

FIGURE 6. Pele ramseyi new genus, new species, holotype male (9.32 × 4.99 mm) (BPBM S 15980). A, ventral view of carapace showing anterior thoracic sternum (abdomen removed); B, outer view of right major chela; C, outer view of left minor chela.

FIGURE 7. Pele ramseyi new genus, new species, holotype male (9.32 × 4.99 mm) (BPBM S 15980). A, right side of carapace; B, left side, frontal view showing antenna, antennules and epistome; C, left eye peduncle and cornea; D, right third maxilliped; E, F, anterior thoracic sternum; G, right thoracic sternites 4 – 6 showing male abdominal locking press-button. cx 5 = coxa of fourth ambulatory leg; go = male gonopore; pb = press-button; st 3 – 8 = thoracic sternites 3 – 8. Scales: A, E, F = 1.0 mm; B – D, G = 0.5 mm.

FIGURE 8. Pele ramseyi new genus, new species, holotype male (9.32 × 4.99 mm) (BPBM S 15980). A, right merus and carpus of cheliped; B, right last ambulatory leg; C, male abdomen; D, E, left G 1 (setae along basal part not drawn); F, left G 2 (setae not drawn). Scales: A, B = 1.0 mm; C – F = 0.5 mm.