Inachus communissimus Rizza, 1839

Guerao, Guillermo & Abelló, Pere, 2007, The first zoea of Inachus aguiarii, Inachus communissimus and Ergasticus clouei (Decapoda, Brachyura, Majoidea) with implications for the systematics of the family Inachidae, Zootaxa 1429, pp. 55-68 : 57-62

Inachus communissimus Rizza, 1839

( Figs 3–4 )

Size: ds= 0.71± 0.02 mm; cl= 0.62± 0.03 mm; n= 8.

Carapace ( Fig. 3 a–c). With long dorsal spine, curved distally backwards, armed with minute spinules; rostral and lateral spines absent; with fronto-median elevation; postero-lateral margin with 6–8 minute denticles; each latero-ventral margin with one densely plumose “anterior seta”; one pair of antero-dorsal setae and one pair of postero-dorsal setae present; eyes sessile.

Antennule ( Fig. 3 d). Uniramous, unsegmented, smooth and conical; endopod absent; exopod unsegmented with 4 terminal aesthetascs and 0–1 seta.

Antenna ( Fig. 3 e). Biramous, protopod very long (spinous process) with two rows of 15–16 spinules; endopod bud approximately 1/3 the size of spinous process; one-segmented exopod equal in length to the spinous process, distally spinulated, with two small midpoint setae.

Mandible. Incisor and molar processes differentiated; mandibular palp (endopod) absent.

Maxillule ( Fig. 4 a). Coxal with seven setae; basial endite with seven setae; endopod two-segmented, proximal segment without setae, distal segment with four terminal setae; exopod seta absent.

Maxilla ( Fig. 4 b). Coxal endite bilobed with 4+3 setae; basial endite bilobed with 5+4; unsegmented endopod not bilobed, with four terminal setae and microtrichia on lateral margin; exopod (scaphognathite) margin with 11 plumose setae, including distal process.

First maxilliped ( Fig. 4 c). Coxa with one seta; basis with nine setae arranged 2+2+2+3; endopod five-segmented with 3,2,1,2,5 (one subterminal and four terminal) setae, respectively; exopod incipiently two-segmented, distal segment with 4 long plumose natatory setae.

Second maxilliped ( Fig. 4 d). Coxa and basis without seta; endopod three-segmented with 0,1,4 setae, respectively; exopod incipiently two-segmented, distal segment with 4 long plumose natatory setae.

Third maxilliped. Present as small buds.

Pereiopods. Present as small buds, chela bilobed.

Abdomen ( Fig. 3 f). With five somites; somite 2 with one pair of dorso-lateral processes directed anteriorly; somites 3–5 with a pair of postero-lateral processes; somite 1 without setae, somites 2–5 with one pair of postero-dorsal setae; incipient pleopod buds on somites 2–5.

Telson ( Fig. 3 f, g). Telson fork with one pair of lateral spines and distally spinulated; inner margin with three pairs of serrulate setae.

Figures

FIGURE 3. Inachus communissimus. Zoea I. a, carapace; b, detail of the dorsal spine; c, detail of the lateral margin of the carapace; d, antennule; e, antenna; f, abdomen, dorsal view; g, detail of the telson. Scale bar of a = 0. 6 mm; scale bar of d – f = 0. 1 mm.

FIGURE 4. Inachus communissimus. Zoea I. a, maxillule; b, maxilla; c, first maxilliped; d, second maxilliped. Scale bars = 0. 1 mm.