Alitropus H. Milne Edwards, 1840

Vigneshwaran, P., Ravichandrana, S. & Kumar Ajith ,, T. T., 2022, Redescription of the monotypic micro-predatory isopod genera Alitropus H. Milne Edwards, 1840 and Barybrotes Schioedte & Meinert, 1879 (Isopoda, Cymothoida), with a taxonomic key to the Cymothooidea Leach, 1814 from India, Journal of Natural History 55 (45 - 46), pp. 2909-2934 : 2913

Genus Alitropus H. Milne Edwards, 1840

Alitropus Milne-Edwards, 1840: 245 . — Schioedte and Meinert, 1879: 403. — Stebbing, 1911: 180. — Ingle and Fernando, 1963: 105. — Bruce, 1983: 782. — Bruce 2009: 214.

Type species. Alitropus typus H. Milne Edwards 1840 , by monotypy.

Remarks. The genus Alitropus is so far considered to be monospecific and it was established by Milne Edwards (1840, p. 245) for the species Alitropus typus collected in the Bay of Bengal. Later, Schioedte and Meinert (1879, p. 402) described another species, Alitropus foveolatus , from an unknown locality, but this addition was assumed to be based on the male A. typus – this species exhibiting considerable sexual dimorphism in the shape of the body. Pillai (1954) gave a preliminary description of a new species, Alitropus dimorphus , from Travancore waters, but in a letter to the Bombay Natural History Society (BNHS) dated 21 November 1955, he said that he had re-examined his material and had concluded that these specimens were a variant of A. typus .

Later, Weber (1892) and Nierstrasz and De Marees van Swinderen (1931) questioned the validity of this genus and regarded it as synonymous with Rocinela . Stebbing (1911), however, thought that the genus was valid. Stebbing (1911) pointed out that the pereopods were slender and unarmed, whereas in species of the genus Rocinela the corresponding pereopods are stout and are armed with robust setae. Alitropus differs from Rocinela in lacking afrontal cephalic projection and in having slender pereopods that lack an enlarged propodus. Bruce (1983) is of the view that the highly reduced coxae on pereonites 5–7 separate Alitropus from the other aegid genera.