Varunidae, H. Milne Edwards, 1853

GUINOT, DANIÈLE, TAVARES, MARCOS & CASTRO, PETER, 2013, Significance of the sexual openings and supplementary structures on the phylogeny of brachyuran crabs (Crustacea, Decapoda, Brachyura), with new nomina for higher-ranked podotreme taxa, Zootaxa 3665 (1), pp. 1-414 : 143-144

Family Varunidae

The male gonopore is sternal. In all varunids that were examined the male gonopore is far from the P5 coxa and from suture 7/8, the distance separating the orifice from the coxa and the suture varying among the genera. A penis emerging in the middle of sternite 8 in a posteriormost location characterises Varunidae ( Guinot 1979a: fig. 52G–J).

The episternite 7 of Varuna practically joins the P5 coxo-sternal condyle ( Guinot 1979a: fig. 54H; Guinot & Bouchard 1998: fig. 23A; N.K. Ng, Davie, Schubart & Ng 2007: fig. 4E). The gonopore, far from the P5 coxa, opens on the vertical slope of the sterno-abdominal cavity; an incomplete sulcus is visible on sternite 8, which is largely exposed. The penis, directed obliquely, shows a calcified basal portion and a well-developed, foliaceous, and soft papilla. The papilla may clearly invaginate inside the gonopore in fresh material, the calcified portion acting as an operculum ( Fig. 36 ). This disposition is similar in Neohelice granulata , where the penis seems to be able to be invaginated. The general configuration is similar in Metaplax H. Milne Edwards, 1852 , with an incomplete sulcus, but the exposed portion of sternite 8 shows a different shape due to the absence of a lateral extension of the first abdominal somite ( Guinot 1979a: fig. 54J). In Cyclograpsus the sulcus is very short ( Karasawa & Kato 2001: fig. 2.23; N.K. Ng, Davie, Schubart & Ng 2007: fig. 4F). The penis of Gaetice resembles to that of Varuna and may be applied against the gonopore, but a deep, complete (instead of incomplete as in Metaplax and Cyclograpsus ) sulcus crosses transversally the exposed portion of sternite 8 (Davie & N.K. Ng 2007: fig. 5H).

In Eriocheir sinensis ( Bouvier 1940: fig. 186B; Guinot 1979a: fig. 53F; Guinot & Bouchard 1998: fig. 23B; N.K. Ng, Guo & Ng 1999: fig. 2Cii), E. japonica (see Komai et al. 2006), Neoeriocheir leptognathus (Rathbun, 1913) (N.K. Ng, Guo & Ng 1999: fig. 2Ci), and Platyeriocheir formosa (Chan, Hung & Tsu, 1995) (N.K. Ng, Guo & Ng 1999: fig. 4A), the male gonopore is similarly far from the P5 coxa and from suture 7/8. Sternite 8 is crossed by a complete sulcus that reaches the developed membranous area situated between the gynglyme receiving the P5 coxo-sternal condyle and the pointed extremity of the episternite 7. A rather large portion of the subdivided sternite 8 remains exposed at the abdominal somites 1–3 levels; additionally, a separate portion of sternite 8 is situated posteriorly. The penis shows a basally calcified proximal portion and a foliaceous papilla. It is difficult to assess if the penis is invaginated in preserved material but in fresh material of Platyeriocheir formosa there is evidence of an invagination, at least of the papilla, the basal portion of the penis acting as an operculum.

The difference between Varuna and Neohelice on one hand and Eriocheir and Platyeriocheir on the other concerns the extension of episternite 7. In Varuna and Neohelice the absence of a membranous area at the level of the sulcus allows the episternite 7 to reach the P5 coxo-sternal condyle, which is not the case in Eriocheir and Platyeriocheir . In Helice ( Guinot 1979a: fig. 54I) the configuration is roughly similar to that in Eriocheir : there is a complete sulcus, but the differences concern episternite 7, which is truncate posteriorly (instead of pointed) and reaches a small beak on sternite 8, the complete sulcus that is covered by the elongated abdominal somite 3, and the shape of the exposed part of sternite 8.

The penis seems to show a rather similar pattern in other varunines, e.g., Chasmagnathus (see Karasawa & Kato 2001: fig. 2.21); Hemigrapsus Dana, 1851 ( Karasawa & Kato 2001: fig. 2.22); Metaplax (see Karasawa & Kato 2001: fig. 2.24); Orcovita (see N.K. Ng & P.K.L. Ng 2002: fig. 2E; 2009: fig. 4A); Pseudograpsus H. Milne Edwards, 1837 (N.K. Ng, Jeng & P.K.L. Ng 2002: fig. 4A); Ptychognathus (see Karasawa & Kato 2001: fig. 2.16; Osawa & N.K. Ng 2006: 59; N.K. Ng 2010: fig. 3C).

The separate status of varunids was based on morphological (N.K. Ng, Guo & Ng 1999), larval ( Spivak & Cuesta 2000; Cuesta et al. 2000, 2001; Cuesta, Luppi, Rodríguez & Spivak 2002; Cuesta, Liu & Schubart 2002), and molecular evidence (Schubart, Cuesta, Diesel & Felder 2000a; Schubart et al. 2001, 2006; see also N.K. Ng, Davie, Schubart & Ng 2007; see also Clark 2006).

Asthenognathus Stimpson, 1858 , was recently removed from Pinnotheroidea to Varunidae in its own subfamily Asthenognathinae Stimpson, 1858 ( Števčić 2005; Ng, Guinot & Davie 2008: 226; De Grave et al. 2009: 45; see also Naruse, Fujita & Ng 2009: 59) or own family Asthenognathidae Stimpson, 1858 (Cuesta et al. 2005; see Palacios-Theil et al. 2009). In Gopkittisak Naruse & Clark, 2009 , a varunid in subfamily Gaeticinae , the male gonopore is at the distal end of suture 7/8 ( Naruse & Clark 2009: 66, fig. 2b; see also Komai 2011; Ng 2012; Komai & Konishi 2012).

Figures

FIGURE 36. Sternal penis protection in Varunidae. Varuna litterata (Fabricius, 1798), male 41.2 × 46.0 mm, New Caledonia (MNHN-B-22720): penis emerging from large orifice on thoracic sternite 8. A, invaginated papilla; B, extended papilla. o, sclerotised sheath acting as an operculum; pa, papilla. Scale bar: 1 mm.