Acinoproscelos, Bamber & Błażewicz-Paszkowycz, 2013

Bamber, Roger N. & Błażewicz-Paszkowycz, Magdalena, 2013, Another inordinate fondness: diversity of the tanaidacean fauna of Australia, with description of three new taxa, Journal of Natural History (J. Nat. Hist.) 47 (25 - 28), pp. 1767-1789 : 1776-1777

Genus Acinoproscelos gen. nov.

Diagnosis (Manca II)

Anarthrurid facies but with setulose labrum (not laterally compressed), maxilliped palp article 3 with six inner marginal and one submarginal setae, slender distal spines on the merus and carpus of pereopods 1 to 3. Antenna articles 2 and 3 with dorsodistal setae; mandible without molar; maxillule endite with four distal setae and one subdistal spines and subdistal seta; maxilliped endite with one long distal seta; third maxilliped palp article with six marginal setae; cheliped basis extended proximally along pseudocoxa, cheliped propodus without lateral fold, ventrally with one seta; carpus of pereopods 4 and 5 with three slender distal spines; uropod endopod of two segments, exopodal process with two distal setae.

Type species

Acinoproskelos vermes sp. nov. by monotypy.

Etymology

From the Greek akaina – a thorn, spine, pro – before, and skelos – leg: hence, spiny foreleg; being the only anarthrurid (so far) to have spines rather than simple setae on the first three pereopods (masculine).

Remarks

The new species described below shows clear affinities to the known genera of Anarthruridae (see Bird 2004; Larsen 2005), particularly to the deep-sea genus Anarthruropsis Lang, 1968 , for example in the cheliped attachment via a large pseudocoxa, the uropod morphology, the reduced mandible, maxillule and narrow maxilliped endites, the lack of tapering of the distal antennular article, the pereopod ischium setation, inter alia. However, Acinoproskelos gen. nov. is unique in the family in having the labrum distally setulose (naked in the other genera), in having as many as six marginal setae on the third maxilliped palp article (up to four in the other genera) and in having slender spines on the merus and carpus of the anterior three pairs of pereopods (simple setae only in the other genera). The otherwise close similarity to the previously described anarthrurid genera precludes any idea of separate familial status.

The present specimen appears to be a manca-II: it is without pereopods on the sixth pereonite, and without pleopods (although the latter is a feature of adults in the type-genus of the family, Anarthrura Sars, 1882 ). Larsen (2005), in describing Anarthruropsis edentula Larsen, 2005 from 15 specimens, remarked on the fact that they were all at the manca-II stage, and postulated possible neoteny in his species. However, both species are known from very small numbers of individuals, and such a condition in either species can only be resolved with further material. Bird (2001, 2004) found over half of the specimens in his material of Thorkelius latiremis (Hansen, 1913) were mancae.