Portunidae, Rafinesque, 1815

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 : 137

Family Portunidae

The male gonopore is coxal, its opening being far from suture 7/8, and thus occupies a posteriormost location in relation to sternite 8. The penis emerges from the anterior margin of the P5 coxa at the limit of the small coxosternal condyle ( Fig. 9 ). A penis enclosing the vas deferens was illustrated in Necora puber (Linnaeus, 1767) by Duvernoy (1853: 146, pl. 2, fig. 9, as Portunus ) and in Liocarcinus corrugatus ( Pennant, 1777) and L. holsatus ( Fabricius, 1798) by Brocchi (1875: figs. 96–99, 104, as Portunus ).

The condition is simple in Carcinus maenas , where the penis is covered by the base of the straight G1 and exclusively protected by the abdomen ( Duvernoy 1853: 149, pl. 2, figs. 7, 8, pls. 3/4, fig. 1; Brocchi 1875: figs. 95, 100, 101; Guinot 1979a: 198, fig. 47F, pl. 13, fig. 1) (See Modalities of penis protection: Basic abdominal and gonopodal protections). The other Portunidae (Portuninae, Podophthalminae, Thalamitinae) show various patterns across genera and species (see Modalities of penis protection: Coxo-sternal protection). The gonopore may form a cup from which the penis emerges, e.g., in Portunus sanguinolentus (Herbst, 1783) and P. pelagicus sensu lato (see the key paper of Lai et al. 2010). In Callinectes ( Fig. 9 ; Cronin 1947: 223, figs. 1, 3, pl. 3, figs. 17–19; Pyle & Cronin 1950: 26: figs. 12, 13; Guinot 1979a: 198, fig. 47G; Rodríguez 1992: fig. 11A) and in the more carcinised Podophthalmus ( Guinot 1979a: 198, fig. 47H), the long penis lies in a concavity, along a sulcus (not a suture but incomplete sulcus), between a roof and a projecting plate, both formed by anterior and posterior expansions of sternite 8, respectively (“anterior plate” and “posterior plate” of sternite 8). The laterally extended G1 offers additional protection, although incomplete, its base covering the curved distal portion of the penis, and the proximal penial portion being protected by the transversely elongated abdominal somite 3. In Thalamita , a raised, calcified plate at the base of the G1 endopodite provides additional protection; the penis, which lies in a slight concavity followed by a sulcus on thoracic sternite 8, has its distal portion covered by the plate and its proximal portion only protected by the abdomen. A coxo-sternal condition is obvious in Cavoportunus dubius , with a long penis overhanged by a marked roof ending in a large, salient spur in the middle of sternite 8; also peculiar is the disposition of the short G1 ( Fig. 55 ).

A particular type of interlocking mechanism between the thoracic sternum and the male abdomen has been observed in many portunids ( Callinectes , Podophthalmus , Portunus , Thalamita ). A small but salient plate located on the posteriormost portion of sternite 8 (which parallels “posterior plate” of sternite 8 that bounds the penis mentioned above) perfectly fits a concavity on the ventral surface of abdominal somite 2 when the abdomen is closed. Although small, this plate is also present in Carcininae. This mechanism appears to be a synapomorphy of the Portunidae .

Figures

FIGURE 9. Penes and two pairs of gonopods acting together as a copulatory complex in Brachyura. Callinectes sapidus Rathbun, 1896 (Portunidae, Portuninae). Copyright ©2003 Steven C. Zinski.

FIGURE 55. Cavoportunus dubius (Laurie, 1906) (Portunidae). A, male 18.1 × 21.9 mm, Réunion (MNHN-B8802): penis (G1 removed), sternal modifications (roof, spur, pocket) and press-button in curved suture 5/6. B, male 15.0 × 19.0 mm, Réunion (MNHN-B8801): G1 in situ and G2. b, press-button; c, coxo-sternal condyle; cx1, cx5, P1, P5 coxa; e7, episternite 7; g, male gonopore; G1, first gonopod; G2, second gonopod; i, inflated portion of G1; m, membrane; m.l., median line; p, penis; po, pocket for inflated portion of G1; s, sternal spur; s8, posterior projection of thoracic sternite 8; 3–8, thoracic sternites 3–8; 4/5– 7/8, thoracic sternal sutures 4/5–7/8 (Courtesy of T.S. Nguyen and P.K.L. Ng).