Typhlotanais spinicauda, : Hansen, 1913

Błażewicz-Paszkowycz, Magdalena, 2007, Figure 6. Typhlotanais Compactus, Female A In Family Nototanaidae Sieg, 1976 And Typhlotanaidae Sieg, 1984, Zootaxa 1598, pp. 1-141 : 116-117

‘ spinicauda ’ group

Diagnosis: Body over seven times as long as wide. Carapace slightly tapering proximally. Pereonites rectangular, carapace and pereonites lateral margin parallel. Pleotelson apex supporting two strong spines; small gap between cheliped basis and proximal margin of pereonite-1 ventrally. Antennule sparsely setose; labrum with relatively long setae on upper margin; mandible molar with crenulated margin with blunt spines or tubercles. Maxilliped basis longer than wide, without seta; endites with two large tubercles and two setae distally. Cheliped relatively narrow (chela three times as long as wide), merus and carpus dorsally well-calcified; pereopod-1 articles without spiniform setae. Pereopods 2 and 3 merus and carpus with spiniform setae; pereopods 4–6 with large prickly tubercle (longer than half of carpus length), propodus dorso-distal setae reaching half of dactylus, dactylus and unguis combined just as long as propodus. Both uropod rami two-articled; endopod proximal article with spiniform setae on inner margin, exopod shorter than endopod proximal article.

Species included: Typhlotanais spinicauda Hansen 1913 , Typhlotanais squamiger n. sp.

Remarks: A pleotelson with the apex supported by two strong terminal spiniform setae, and spiniform setae on the inner margin of the uropod endopod proximal article in Typhlotanais spinicauda and T. squamiger n. sp. are unique characters among known ‘typhlotanaids’ and the potential for erecting a new genus to which to assign these two species is fairly high. Because only a few specimens were available for study, resolution of a generic status is premature; instead, a ‘ spinicauda ’ morpho-group is proposed to emphasize the close similarity between T. spinicauda and T. squamiger n. sp.

T. spinicauda and T. squamiger share large prickly tubercles and a general body habitus with T. mixtus possibly indicating a phylogenic affinity. The last taxon, however, lacks spiniform setae on the merus of pereopods 2 and 3, and it has a large gap ventrally between the cheliped basis and the proximal margin of pereonite-1 (the gap is much smaller in the ‘ spinicauda ’ group).

The presence of strong terminal spines on the pleotelson and a row of spiniform setae on the inner margin of the uropod endopods is characteristic for Tanabnormia cornicauda Gu ṭu, 1986. This character suggested to Guṭu the possibility of a predatory potential of the species, although no specific evidence for this kind of feeding was given. During the dissection of the one specimen of T. squamiger n. sp. the gut was found to contain only fine particles resembling fine benthic sediments, similar to the gut contents found in most shallow water tanaids ( Błażewicz-Paszkowycz and Ligowski, 2002). This feature may have more to do with defense of the posterior of the animal when in its tube or burrow.