Spinodiosaccus, Gómez & Corgosinho & Rivera-Sánchez, 2021

Gómez, Samuel, Corgosinho, Paulo Henrique Costa & Rivera-Sánchez, Karen I., 2021, Proposal of new genera and species of the subfamily Diosaccinae (Copepoda: Harpacticoida: Miraciidae), European Journal of Taxonomy 759 (1), pp. 1-62 : 26-27

Spinodiosaccus gen. nov.

urn:lsid:zoobank.org:act:B8A6B755-8375-48B0-BC31-EBCCB4B9F9DE

Type and only species

Spinodiosaccus primus gen. et sp. nov., by monotypy.

Diagnosis (based on Spinodiosaccus primus gen. et sp. nov.)

Miraciidae : Diosaccinae . Body fusiform. Rostrum not fused to cephalothorax, elongate, almost as long as the first, second and third antennulary segments combined, with one subdistal sensilla on each side issuing at the third quarter of its length. Pro- and urosomites without extensions; with a flexible unsclerotized cuticle between prosome and urosome, the latter seemingly more evident in the male. Female genital double-somite (genital – second urosomite – and third urosomites fused) completely fused ventrally, with a dorsolateral cuticular rib marking former division between somites. Anal somite trapezoidal, without anal operculum. Caudal rami short, 1.6 times as wide as long in dorsal view, unornamented, with slender tube pore ventrally; with seven setae. Female antennule eight-segmented, with aesthetasc and seta fused basally on fourth segment and with apical acrothek on last segment. Male antennule haplocer, 11-segmented, with aesthetasc and seta fused basally on fifth segment and with apical acrothek on last segment. Antennulary setae typically smooth. Antenna with allobasis; exopod three-segmented, armature formula 1-1-1,3,0. Mandibular palp biramous; endopod one-segmented, exopod two-segmented. Maxillule biramous; rami one-segmented. Maxilla with three endites; ENP one-segmented. Maxilliped subchelate; (syn)coxa with four, basis with two setae; ENP one-segmented, with claw and three accompanying setae. P1–P4 with three-segmented rami. P1–P2 EXP shorter than endopod, P3 EXP and ENP of approximately the same length, P4 ENP shorter than EXP. Male P1 basis sexually dimorphic, with inner unipinnate spine and inner modified accessory spine. Male P2 sexually dimorphic, two-segmented; first segment with one inner seta; second segment with two inner, one inner subdistal almost straight element, and two setae (one medial, one apical) issuing from elongate cylindrical extension fused to segment basally, and one strong outer subdistal spine, the latter strongly tapering distally. P2–P4 EXP1 without, EXP2 with inner seta; P2–P4 ENP1 with inner seta; P2 ENP2 with two, P3–P4 ENP2 with one inner seta, inner distal seta of EXP3 visibly shorter than other elements of same segment. Both P5 EXP separated in the female, baseoendopods fused medially in the male; rami of P5 distinct in both sexes; P5 EXP with six setae in both sexes, whip-like in the female, two medial outer elements transformed into short spines in the male; P5 endopodal lobe with five setae in the female, with two setae in the male.

Armature formula of P1–P5 as follows:

Sexual dimorphism expressed in the male antennule, P1 basis, P2 ENP, P5, P6, and in the genital and third urosomite separated in males.

Etymology

The prefix ‘spino’ from the Latin ‘spīna’, ‘spine’, refers to the two medial elements of the male P5 EXP modified into strong short spines. Gender masculine.

Apomorphies of Spinodiosaccus gen. nov.

This new genus can easily be recognised by i) the male A1 with 11 segments resulting from the reexpression of the plesiomorphic condition, ii) the absence of an inner seta on the P1 EXP2 and iii) the absence of inner armature on P2–P4 EXP1.

Figures

Armature formula of P1–P5 as follows: