Ektraleptochelia, Bamber, Roger N. & Marshall, David J., 2015

Bamber, Roger N. & Marshall, David J., 2015, Tanaidaceans from Brunei, V. The Leptocheliidae (Crustacea: Peracarida: Tanaidacea), with four new species, Zootaxa 3948 (3), pp. 342-360 : 355-356

Genus Ektraleptochelia gen. nov.

Diagnosis: Female: Catenariin with eyes present, pigmented. Antennule proximal flagellar segment fused to distal peduncle article. Antenna peduncular article 3 with fused distal spine. Maxillular endite spines blunt. Cheliped carpus with setose dorsal margin. Uropod exopod one-segmented.

Type species. Ektraleptochelia phoxops sp. nov. by original designation.

Etymology. From the Greek ektrapelos— strange, and Leptochelia .

Gender. Feminine.

Remarks. Ektraleptochelia gen. nov. shows the distal structure of the antennule, with two flagellar segments, characteristic of the Catenariinae ; however, the proximal flagellar segment is fused to the third peduncular article, while in Catenarius the type-genus of the subfamily, the two segments are distinct. The one aesthetasc present is not attached to the distal flagellar segment, which only bears four simple setae, but to the proximal flagellar segment, as characteristic of the subfamily.

Note that, even after fusion, the flagellar segment is identifiable, as aesthetascs are only borne by flagellar segments. In some other leptocheliid genera, such as Mesotanais Dollfus, 1897 and Konarus Bamber, 2006 , the single flagellar segment is fused to the peduncle but still bears the aesthetasc, which then appears to be attached to the distal peduncular article.

The only previously-known genus of the Catenariinae , Catenarius , has pointed distal spines on the maxilliped endite and a two-segmented uropod exopod, features which were considered diagnostic of the subfamily by Bamber (2013b). However, as has been seen above, variation in these last two characters also occurs within the Konariinae and the Leptocheliinae , so now have to be considered variable within subfamilies rather than diagnostic. Instead, they serve to distinguish the catenariin genera.

The complete fusion of the distal spine on the third article is unusual, but this situation is found in Leptochelia guduroo Bamber, 2008 , while L. daggi Bamber, 2005 and L. karragarra Bamber, 2008 show partial fusion of the antennal article 3 spine (although all three have distal spines on article 2). Within the Paratanaidae , such species as Paratanais incomptus Bird & Bamber, 2013 and Aparatanais malignus ( Larsen, 2001) show intraspecific variation in the fusion or articulation of this spine. This pattern clearly indicates that the feature in Ektraleptochelia and L. guduroo is a fused spine rather than an apophysis.

Other features common to Catenarius and Ektraleptochelia are the proximal setae on the dactyli of the cheliped and pereopod 1, and the proportions of the propodus-dactylus-unguis of pereopod 1.

The diagnosis of the subfamily has been modified above in the light of the data from the new genus.