Deltamysis Bowman & Orsi, 1992

Scripter, Matthew J., Price, W. Wayne & Heard, Richard W., 2020, Redescription of Deltamysis holmquistae Bowman & Orsi, 1992 (Crustacea Mysida: Mysidae), a mysid species new to the Atlantic Ocean with observations on the taxonomic status of Kochimysis Panampunnayil & Biju, 2007, Zootaxa 4729 (4), pp. 501-518 : 504

Genus Deltamysis Bowman & Orsi, 1992

Synonym: Kochimysis Panampunnayil & Biju, 2007

Emended diagnosis (Based on adult D. holmquistae paratypes and western Atlantic material): Carapace with anterior margin produced into a short, rounded rostrum. Male antennular peduncle, article 3 with reduced, rounded, sometimes indistinct, setiferous lobe. Antennal scale with transverse suture, separating short distal article. Thoracic endopod 2 with carpus and propodus simple in female; with papillations on lateral margins in male. Thoracic endopod 3 not stouter than other thoracic endopods. Thoracic endopods 3 and 4 with carpopropodus divided into 3 subarticles. Thoracic endopods 5–8 with carpopropodus divided into 4 subarticles. Pleopods rudimentary in both sexes. Uropodal endopod without spiniform setae along medial margin in region of statocyst. Penis of moderate size, extending forward to bases of thoracopods 4–5. Telson entire, lateral margins armed along posterior 0.25–0.37 length with 6–9 spiniform setae per margin (including apical setae); apex with 2 pairs of spiniform setae, inner pair 0.25–0.50 times as long as outer pair.

Remarks: We compared our morphological observations on the paratypes of D. holmquistae from northeastern Pacific (California) and northwest Atlantic specimens (Florida and Texas) examined during the present study with the specific description of K. pillaii from the northern Indian Ocean. There was a significant degree of intraspecific morphological variation observed within the type series of D. holmquistae , as well as, in specimens from the northwest Atlantic (see Table 1 ). These observations demonstrated a high degree of overlap for the characters used in the generic and specific designations for K. pillaii and these findings strongly indicate that the two taxa represent a single variable and geographically dispersed species (see Discussion). Based on these comparisons and the morphological similarities, we herein formally subsume the monotypic genus Kochimysis Panampunnayil & Biju, 2007 , as a junior subjective synonym of Deltamysis Bowman & Orsi, 1992 .