Taxonomic revision of Brasiloniscus (Oniscidea, Pudeoniscidae) with description of a new species

The Neotropical genus Brasiloniscus, erected by Lemos de Castro (1973), is revised and validated herein. The genus was originally described including two species, B. maculatus and B. verrucosus, but no type species was designated. According to § 13 of ICZN (1999) the name of the genus is therefore unavailable. Both species are redescribed, and B. maculatus is designated as the type species of the genus. The genus name will thus be available for the systematics of Oniscidea. In addition, a new species, B. littoralis gen. et sp. nov., is described based on material from the Brazilian Atlantic Forest from the state of Rio de Janeiro.


R e s e a r c h a r t i c l e
urn:lsid:zoobank.org:pub:EA9CCBD2-8E44-4AFA-A5EE-A5913D66965A

Remarks
The characters used by Lemos de Castro (1973) to defi ne the genus, such as cephalon with large frontal shield, pereonite 1 epimeron with well-developed dorsolateral furrow, pereonites 2 and 3 epimera with ventral lobes, and neopleurae 3-5 with distal portion not narrowed, are in fact characteristics observed at the family level, since these are also present in Pudeoniscus.
The genus Brasiloniscus gen. nov. differs from Pudeoniscus in having the pereonite 1 epimeron with lateral schisma and ventral lobe well developed, cephalon with frontal shield larger and antennal fl agellum with articles subequal in length.

Remarks
Lemos de Castro (1973) mentioned the absence of respiratory area on pleopod exopods. However, the examination of the type material revealed the presence of uncovered respiratory areas in all pleopod exopods. New illustrations are provided here along with characters that were not mentioned in the original description. (Lemos de Castro, 1973)  BODY. Habitus in lateral view as in Fig. 3A. Material depigmented due to long preservation in ethanol 70% (Fig. 7B). Dorsum (Fig. 3A) with well-developed ribs and tubercles on median and paramedian areas of pereonites; noduli laterales short, inserted far from lateral margin and in each pereonite progressively near to posterior margin. CEPHALON ( Fig. 3B-C). Lateral lobes slightly bent upwards, frontal shield with lateral sides concave; eyes consisting of 15 ommatidia.
MOUTH. Buccal pieces (not drawn) as in B. maculatus.

Remarks
Lemos de Castro (1973) provided the description of this species based on females. Even though the respiratory area can be seen, it is not possible to compare the male characters. Also, as mentioned by Lemos de Castro (1973), B. verrucosus gen. et comb. nov. differs from B. maculatus gen. et comb. nov. by the distinct dorsal tuberculation, the shape of telson with distal portion narrower, the shape of schisma on pereonite 1, and the shape of ventral lobes on pereonites 1 and 2. All these characteristics were confi rmed here, however male characters remain unknown.

Diagnosis
Body with dorsal surface slightly tuberculate, telson triangular with lateral sides concave and distal portion narrow, dactylar seta with fringe of small setae on apex, male pleopod 1 exopod as long as wide with deep re-entrance on distal portion, and male pleopod 1 endopod with distal portion acute bearing a slight lobe on inner margin.

Etymology
The new specifi c epithet refers to the Latin adjective 'littoralis', used to describe the seashore/coast, in reference to the locality where the specimens were collected.

BODY. Habitus in lateral view as in
PLEOPOD EXOPODS. Respiratory areas as in diagnosis.

Remarks
The new species resembles B. maculatus gen. et comb. nov. in the shape of body and male pleopod 1; it can be easily distinguished in the shape of the telson, pereopod 7 base without lobe on distal sternal margin, and dactylar seta with fringe of thin setae on the distal portion.

Discussion
The phylogenetic relationships of Pudeoniscidae were discussed by Wägele (1989) and Schmidt (2003), both authors recovered the family with an uncertain position within the Oniscidea. Schmidt (2003) included Pudeoniscidae in a clade named 'taxon 6', without any synapomorphic characters. Based on P. birabeni Vandel, 1963, the author considered the respiratory fi elds Oniscus-type (= Atracheodillotype, see also Paoli et al. 2002) or the Y-or T-shaped dorsal scale-setae as possible synapomorphies to the family. Yet no clear synapomorphic characters are known (Schmidt 2008), and despite all efforts the phylogenetic position of the family is still unknown.
Brasiloniscus gen. nov. and the characters of its species have been revised, and the genus validated herein. The genus is mainly recognized by the epimera of pereonite 1 with dorsolateral furrow to fi t antennae during conglobation and a schisma on the postero-lateral corner, shape of the telson, antennal fl agellum with three articles, uropod with the exopod inserted distally, and uncovered Atracheodillotype respiratory lungs on pleopod exopods.