Planopilumnidae Serène, 1984

Ng, Peter K. L., 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, pp. 33-61 : 34-35

Family Planopilumnidae Serène, 1984

Planopilumninae Serène, 1984: 11. — Davie 2002: 201.

Planopilumninae [sic] – Števċić 2005: 67. — Ng et al. 2008: 179.

Remarks. The genus Planopilumnus Balss, 1933 , was originally established for five species and subspecies, Pilumnus spongiosus spongiosus Nobili, 1905 (designated type species), Planopilumnus spongiosus orientalis Balss, 1933 , Planopilumnus fuscus Balss, 1933 , Pilumnus vermiculatus A. Milne Edwards, 1873 , and Pilumnus labyrinthicus Miers, 1884 . In the same year, Ward (1933) established a new genus, Rathbunaria , for a new species, Rathbunaria sculptissima , from Australia. Rathbunaria Ward, 1933 , and Rathbunaria sculptissima Ward, 1933 , have long been regarded as junior synonyms of Planopilumnus Balss, 1933 , and Planopilumnus spongiosus orientalis Balss, 1933 , respectively ( Balss 1938; Davie 2002; Ng et al. 2008). Balss (1938) subsequently transferred Pilumnus penicillatus Gordon, 1930 , to Planopilumnus ; and in the subsequent years, two more species were added, Plano. minabensis Sakai, 1969 , and Plano. pygmaeus Takeda, 1977 .

Balss (1933) did not check Nobili's (1905) types of Pilumnus spongiosus from the Red Sea, the species he named as the type species of Planopilumnus . Nor did he critically examine the gonopods of his new subspecies, P. spongiosus orientalis . The types of both species have now been checked and both are clearly separate species. The problem is that neither P. spongiosus nor P. orientalis are pilumnids as understood at present. Their G1s are relatively stout and straight, and the distal parts are lined with numerous short, stout spines, with the G2 basal segments proportionately much longer. Ng & Clark (2000a: 238–239), in reviewing the state of pilumnid classification, commented that “ Serène (1984: 11) very briefly proposed a revised classification of the Pilumnidae , in which he recognised five subfamilies, namely Pilumninae Samouelle, 1819 , Halimedinae Alcock, 1898 , Heteropanopeinae Alcock, 1898, and two new subfamilies, Planopilumninae and Heteropilumninae. No diagnoses or comments were provided, and the only information on these subfamilies was in a footnote ( Serène, 1984: 11) and in the keys to the Xanthoidea ( Serène, 1984:15). Under current rules of zoological nomenclature both the Planopilumninae Serène, 1984, and Heteropilumninae Serène, 1984, are available names. How valid these subfamilies are is currently difficult to assess. The Planopilumninae s. str. is certainly not a member of the Pilumnidae as the type species of the genus, Planopilumnus Balss, 1933 , P. spongiosus ( Nobili, 1906) , is not a pilumnid but a goneplacid allied to members of the Carcinoplacinae (Ng, unpublished data).” Ng et al. (2001: 33) subsequently commented that with “regards to the Planopilumninae, the type species of the type genus, Planopilumnus spongiosus ( Nobili, 1905) , is actually not a pilumnid at all but closer to goneplacids like the Pseudoziinae instead. The genus Planopilumnus as currently understood, is heterogeneous.” Davie (2002: 190) agreed with these observations and even suggested that the genus may belong to its own family. Davie (2002: 392) also noted that the “the Planopilumninae is tentatively recognised but removed to the Goneplacidae , with its closest relatives probably with the Pseudoziinae genera. Planopilumnus labyrinthicus ( Miers, 1884) is, however a typical pilumnid, and is here treated as a Pilumnus species until a new genus is described to accommodate it (P.K.L. Ng in prep.)”. Števčić (2005) recognised the Planopilumnidae as a family in his Goneplacoidea MacLeay, 1838, with only one genus, Planopilumnus , but without any discussion.

In the most recent appraisal, Ng et al. (2008: 145) added that “if Planopilumnus (here restricted to P. spongiosus and P. orientalis ) is a pseudoziid, the rest of the species which have been placed in Planopilumnus by many authors need to reappraised. The problem is that of the remaining six species of ‘ Planopilumnus ’, Planopilumnus fuscus Balss, 1933 , is also quite different from the rest. In his synopsis of the Brachyura, Števčić (2005) appended a list of new genera he recognised towards the end of the work which he could not place in any of his superfamilies, and designated type species for each. One of these genera was ‘ Lazaropilumnus ’ for which the selected type species was Planopilumnus minabensis Sakai, 1969 ( Števčić, 2005: 133) . However, as he did not provide any description, diagnosis or indication, ‘ Lazaropilumnus ’ is a nomen nudum and not an available name ….. In this paper, Pilumnus labyrinthicus Miers, 1884 , Pilumnus vermiculatus A. Milne-Edwards, 1873 , Pilumnus penicillatus Gordon, 1930 , Planopilumnus minabensis Sakai, 1969 , and Planopilumnus pygmaeus Takeda, 1977 , all characterised by having oval carapaces, three low but visible lobiform anterolateral teeth, and a labyrinth-like pattern of setae on their carapace, will be referred to a new genus. Planopilumnus fuscus Balss, 1933 , with its anterolateral margin armed only with two strong teeth, the carapace with dense, short wool-like pubescence not arranged in any patterns, and a very characteristic suborbital margin, will be referred to its own genus. For the purposes of this synopsis, we transfer all of them to Pilumnus sensu lato for the moment. Pilumnus pygmaeus Boone, 1927 , is a senior homonym of Pilumnus pygmaeus ( Takeda, 1977) because of the latter’s temporary transfer from Planopilumnus . This homonymy will be resolved when Pilumnus pygmaeus ( Takeda, 1977) is referred to a new genus by Ng (in prep.) and there is thus no reason to establish a replacement name.”

The two new pilumnid genera in question are here formally named and diagnosed. For the five species in question, in addition to the diagnostic structures of their G1 and G2, which immediately distinguish them from all pseudozioids, the structure of their penis is also distinctive. As noted by Ng et al. (2008: 135), all pilumnoids have a penis that protrudes from a gonopore that is directly on the condyle of the fifth ambulatory coxa ( Fig. 19 B). In contrast, the penis of planopilumnids protrudes on a gonopore that is anterior to the proximal portion of the condyle ( Fig. 19 A). The vulvar structure also differs. Adult female planopilumnids examined have relatively large vulvae which do not have operculums and are positioned close to each other near the centre of the thoracic sternum. Pilumnids on the other hand, have relatively much smaller vulvae without operculums which are positioned further apart.

The Planopilumninae Serène, 1984, is here recognised as a distinct family in the Pseudozioidea Alcock, 1898 (see discussion in Ng et al. 2008: 135, 136, 179). As it is currently arranged, the Planopilumnidae contains four genera: Haemocinus Ng, 2003 ; Planopilumnus Balss, 1933 ; Platychelonion Crosnier & Guinot, 1969 ; and Rathbunaria Ward, 1933 . The latter, which was synonymised under Planopilumnus shortly after it was described, is here recognised as a distinct genus.

Comparative material. Platychelonion planissimum Crosnier & Guinot, 1969 : holotype male (31.4 × 21.3 mm) ( MNHN), Pointe-Noire, Congo (R.O.C.), 10–20 m, in net with lobsters, coll. A. Crosnier, 7 Oct. 1967. Haemocinus elatus ( A. Milne-Edwards, 1873) : 1 male (21.7 × 16.2 mm) (The Naturalis, Leiden; RMNH 32048), Wagu, Kii Islands, Mie Prefecture, Japan, coll. N. Yamashita, 1978/1979; 1 female (25.8 × 17.5 mm) ( ZRC), Balicasag Island, Panglao, Bohol, Visayas, Philippines, intertidal reef, coll. A. Porpetcho & P. F. Clark, Jun. 2002.

Figures

FIGURE 19. Position of penis. A, Planopilumnus spongiosus (Nobili, 1905), male (25.6 × 19.0 mm) (ZRC 2009.349), denuded; B, Vellumnus labyrinthicus (Miers, 1884), male (13.5 × 10.8 mm) (ZRC 1999.397), denuded. Abbreviations: cn = condyle of coxa; cx 5 = coxa of fifth ambulatory leg; G 1 = first male pleopod; p = penis; s 5 – s 8 = thoracic sternites 5 to 8, respectively.