Inachidae, MacLeay, 1838

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 : 126

Family Inachidae

The male gonopore is coxal. It occupies a posteriormost location in relation to sternite 8, far from suture 7/8 ( Figs. 49B, C , 50A ). Its large opening is situated at the limit between the anterior margin of the coxo-sternal condyle and that of the coxa itself, the P5 coxo-sternal condyle fitting a gynglyme in a notch on the lateral border of sternite 8. The penis exits from the gonopore close to the thick articulating membrane of the P5 coxa (the markedly moveable coxae of all pereopods have thick articulating membranes, probably correlated with decoration behaviour) and it is overhanged by a roof formed by an excavation of sternite 8 ( Fig. 49B ). The trend to a coxo-sternal condition is obvious (See Modalities of penis protection: Coxo-sternal protection). A posteriormost location of the male gonopore also occurs in Oregoniidae ( Fig. 1A ), Inachoididae ( Fig. 50C, E ), and all other Majoidea ( Fig. 50G ) (see Family Inachoididae below; Monophyletic Heterotremata: Superfamily Majoidea ; Affinities between Inachoididae and Inachidae ).

Figures

FIGURE 1. A, Anatomical relationships of penis and gonopods in Brachyura exemplified by Chionoecetes opilio (Fabricius, 1788) (Oregoniidae) (modified from Beninger et al. 1991: fig. 1C; G1 basal setae not figured); B–D, schematic representation of the dispositions of male gonopore, penis, and ejaculatory duct (indicated by dotted line) in Brachyura: B, C, perforation of P5 coxa by the ejaculatory duct: B, coxal gonopore, with penis emerging from P5 coxa (Podotremata and Heterotremata pro parte); C, coxo-sternal condition, with coxal gonopore and penis emerging at level of thoracic sternal suture 7/8 (Heterotremata pro parte); D, E, perforation of thoracic sternum by ejaculatory duct: D, sternal gonopore at the suture 7/8 level; E, sternal gonopore far from suture 7/8, in posteriormost location in relation to sternite 8. a1, abdominal somite 1; cx5, P5 coxa; g, gonopore; G1, first gonopod; G2, second gonopod; p, penis; p5, fifth pereopod; 7, 8, thoracic sternites 7, 8; 7/8, thoracic sternal suture 7/8. Scale bar: 1 mm (A).

FIGURE 49. Capartiella longipes (Capart, 1951) (Inachidae), male 8.2 × 6.5 mm, Dahomey (= Benin) (MNHN-B19590). A, carapace, dorsal view: notice exposed pleurites 5–8; B, ventral view; C, thoracic sternum, abdomen lifted, G1 lowered; D, detail of pleotelson with moveable flap supposedly homologous to vestigial uropod. a1, a5, abdominal somites 1, 5; b, pressbutton; c, carapace edge; cx1, P1 coxa; e5–e8, exposed pleurites 5–8; f, flap; G1, first gonopod; pt, pleotelson (somite 6 fused to telson); r, roof formed by thoracic sternite 8; 3–8, thoracic sternites 3–8.

FIGURE 50. A–G. Thoracic sternum (A, C, E, G) and ventral surface of abdomen (B, D, F) of Inachidae (A, B), Inachoididae (C–F), and Majidae (G). A, B, Inachus dorsettensis (Pennant, 1777), male 20.0 × 18.0 mm, France, Saint Martin de Ré (MNHN-B17337); C, D, Collodes leptocheles Rathbun, 1894, male 17.5 × 13.2 mm, Gulf of Mexico (MNHN-B14055); E, F, Pyromaia tuberculata (Lockington, 1877), male 17.0 × 12.2 mm, Baja California (MNHN-B9290); G, Prismatopus harmandi (Bouvier, 1906), male 46.0 × 24.5 mm, holotype, vicinity of Tokyo (MNHN-B22330). H. Palicus caronii (Roux, 1828), male 6.0 × 7.0 mm, eastern Atlantic (MNHN-B16335): ventral surface of abdomen with long socket on somite 6. b, press-button.