Pulcratis Ng and Huang, 1997

Pulcratis Ng and Huang, 1997 View in CoL

Pulcratis Ng and Huang, 1997: 272 View in CoL . — Ng et al., 2008: 206. — De Grave et al., 2009: 43.

Type species. Pulcratis reticulatus Ng and Huang,

1997, by original designation, gender masculine.

Remarks. The subfamilial placement of Pulcratis in Xanthidae requires further evaluation. Ng and Huang (1997) assigned it to Zosiminae Alcock, 1898 (sensu Serène, 1984), primarily due to the cristate margins of the meri of the ambulatory legs, and cited its similarity in general form and color pattern to Paratergatis Sakai, 1965 (type and only species: P. longimanus Sakai, 1965 ). Jeng and Ng (1998) commented further on the morphological distinctions between Paratergatis and Pulcratis .

Subsequently another new genus, Ovatis Ng and Chen, 2004 (type species: O. simplex Ng and Chen, 2004 ; monotypic), was described from the South China Sea. Ng and Chen (2004) considered Ovatis to be closely related to Liagore De Haan, 1833 , and assigned it to Xanthinae MacLeay, 1838 . They also noted the morphological similarities among the xanthines, Ovatis and Liagore , and the zosimines, Paratergatis and Pulcratis , leading them to note that the only definitive morphological character being used to separate members of the two subfamilies is whether or not the articles of the ambulatory legs are cristate, and even then, there are difficulties in assessing the degree of such cristation. Ng et al. (2008) also pointed out incongruencies in the larval morphology of members of these two groups (see also Ng and Clark, 1994; Clark et al., 2004).

A comprehensive phylogeny of the family Xanthidae was provided by Lai et al. (2011) on the basis of four molecular markers (viz., 12S, 16S, COI and H3) sequenced from 147 species. In their consensus tree ( Lai et al., 2011: fig. 1), the subfamily Xanthinae was shown to be polyphyletic, with members scattered across 10 distinct clades (Xan 1–10) with varying levels of support. The nominal type genus, Xantho Leach, 1814 , represented by X. pilipes A. Milne-Edwards, 1867 , and X. hydrophilus (Herbst, 1790) , formed its own well-supported clade (Xan 4) distinct from all the other ‘xanthine’ clades. Pulcratis reticulatus was nested in a well-supported clade (Xan 1) together with some species of Demania Laurie, 1906 [ D. cultripes ( Alcock, 1898) , D. scaberrima ( Walker, 1887) and D. intermedia Guinot, 1969 ], Neoxanthias Ward, 1933 [ N. michelae Serène and Vadon, 1981 ], Odhneriana Ng and Low, 2010 [ O. echinus ( Alcock, 1898) ], and Liagore De Haan, 1833 ( L. rubromaculata De Haan, 1835 ). Likewise, the subfamilies Zosiminae Alcock, 1898 , and Liomerinae Sakai, 1976 , were also shown to be polyphyletic, with members split into two distinct clades for each subfamily. Paratergatis longimanus actually has closer relationships to true liomerines as it was in a separate well-supported clade (Lio 1; i.e., Liomerinae sensu stricto) together with some species of Liomera Dana, 1851 [viz., L. tristis ( Dana, 1852) , L. venosa (H. Milne Edwards, 1834) , L. bella ( Dana, 1852) , L. cinctimana ( White, 1847) ], Lipkemera Davie, 2010 [viz., L. corallina ( Takeda and Marumura, 1997) and L. holthuisi Mendoza, 2010 ] and an undescribed genus and species [viz., “New genus 1 sp. nov.”]. Ovatis was not represented in the molecular tree.

Given the presently available evidence, Pulcratis is tentatively assigned to Xanthinae sensu lato (viz., Ng et al., 2008) pending a revision of this polyphyletic subfamily. Lai et al. (2011: 430, 431) did propose some diagnostic characters for the xanthine clade (Xan 2) to which Pulcratis belongs: “The characters that define this clade are the presence of distinct longitudinal rows of dense setae on the dactylus of all four ambulatory legs, a broad male thoracic sternite 7, abdominal somites 1 and 2 broad; male thoracic sternite 8 just visible when abdomen is closed, episternites 5–7 delimited by a sulcus, and coxo-sternal condyle of P5 inserted between abdominal somites 2 and 3.” Not all of these characters, however, can be observed in Pulcratis . In particular, the episternites 5–7 do not have sulci separating them from their respective thoracic sternites. The xanthid crab group, ‘tribe Liagorini’ (viz., Števčić, 2005) may be an available name for this clade (i.e., perhaps as subfamily Liagorinae ), but the formal action required is not part of the scope of this current paper, as the proper taxonomic ranking and morphological diagnosis can only be made in the context of a familywide revision and after sufficient examination of a large number of related taxa.