Mexicope Hooker, 1985

Riehl, Torben, Schienbein, Katharina Ellen & Mifsud, Constantine, 2024, A new species of Mexicope Hooker, 1985 (Crustacea, Isopoda) — the first record of Acanthaspidiidae Menzies, 1962 from the Mediterranean Sea, Biodiversity Data Journal 12, pp. e 121508-e 121508 : e121508-

Mexicope Hooker, 1985

Composition: Mexicope westralia Just, 2001 , Mexicope sushara Bruce, 2004 and Mexicope maletensis Riehl & Schienbein , sp. nov.

Mexicope kensleyi Hooker, 1985 Hooker 1985: pp. 261-265; figs. 5 and 6.

Description

Synonymy

Mexicope Hooker, 1985: 261 . – Just (2001: 913); Bruce (2004: 2) ( Hooker 1985, Just 2001, Bruce 2004).

Diagnosis

Cehalothorax laterally with eyestalks and developed or reduced eyes; eyestalks directed laterally or anterolaterally, with preocular spine. Pereonites 1 and 5–7 with single lateral projection; pereonites 3–4 with bifid lateral projections; pereonite 2 lateral projection single or bifid; lateral projections with apical short setae; pereonites 2–4 and 6–7 posterior projections with long setae recurving dorsally over tergites, pereonite 5 without long setae. Pereonite 7 with sternal spine. Pleotelson margins finely serrated, with spine-like, short, curved setae. Antennula length ca. 0.33 antenna length, article 1 and 2 subequal in length. Mouthparts prognathous; mandibular molar tapering or pointed with apical long setae; mandibular palp present or absent; maxilliped epipod short, reaching half way between coxobasal articulation and palp insertion. Pleopod II fringed with long setae, longest apically; stylet coiled. Uropod length equal or longer than pleotelson, peduncle and rami long and slender; rami length equal or longer than peduncle length.

Remarks on diagnosis

This diagnosis has been completely revised to overcome the inconsistencies and overlaps of previous diagnoses.

Taxon discussion

A new diagnosis for Mexicope is presented here because previous diagnoses of the genera Ianthopsis and Mexicope ( Just 2001, Bruce 2004) show significant overlap in some character states leading to difficulties to differentiate between these genera and to classify the new species described here.

Character states that support classification as either Ianthopsis or Mexicope are the absence of dorsal tubercles on the cephalothorax, the presence of eyes on eyestalks, single lateral projections on pereonite 1, the absence of tergal spines or humps, a fringe of long setae laterally on the second pleopod basis which are longest apically, finely serrated pleotelson margins and uropod rami that are at least as long as the peduncle. The presence of a simple, bulge-shaped rostrum, the antennula length of 0.25 times antenna length, the absence of a triangular lobe on antenna article 6 and the short, curved, robust setae on the pleotelson on the one hand speak for a classification of the new species as Ianthopsis according to the previous diagnosis.

The classification of the new species as Mexicope , on the other hand, is supported by the presence of a pre-ocular spine, rows of elongate, simple setae on the posterolateral projections of pereonites 2–4 and 6–7, the presence of a sternal spine on pereonite 7, prognathous mouthparts, a strongly tapering, pointed mandibular molar with long apical setae, the lack of a mandibular palp, a short maxilliped epipod reaching only half way between the coxo-basal articulation and the palp articulation, a coiled pleopod II stylet and uropods that are as long as the pleotelson.

In summary, over ten, partially complex characters suggest the classification as Mexicope as opposed to only four, relatively weak characters in favour of Ianthopsis (see Table 1).