Chaimowiczia, Cardoso 1 & Bastos-Pereira 1 & Souza 2 & Ferreira 1, 2021

Cardoso 1, Giovanna Monticelli, Bastos-Pereira 1, Rafaela, Souza 2, Leila Aparecida & Ferreira 1, Rodrigo L., 2021, Chaimowiczia: a new Iuiuniscinae genus from Brazil (Oniscidea, Synocheta, Styloniscidae) with the description of two new troglobitic species, Subterranean Biology 39, pp. 45-62 : 45

Genus Chaimowiczia gen. nov.

Type species.

Chaimowiczia tatus sp. nov.

Diagnosis.

Body non-volvational. Cephalon with antennal lobes, distinct suprantennal line bent in middle, vertex with lateral grooves. Body outline continuous with pereonites epimera well developed, widely separated, pleonites 1 and 2 bridge the gap between pereon and pleon, pleonites 3-5 with epimera well developed. Telson with subtriangular distal half depressed with rounded apex. Antennula of three articles covered with setae, distal article with two apical aesthetascs. Antenna with flagellum of three distinct articles covered with setae. Mandibles pars molaris large and projected. Maxillula outer ramus with entire teeth and two long and thick setose stalks; inner ramus with three penicils at apex. Maxilla inner lobe wider than outer lobe. Maxilliped basis trapezoidal; endite bearing one penicil between two strong teeth. Pereopods with unbranched dactylar setae. Genital papilla lanceolate. Male pleopod 1 exopod and endopod subequal in length, endopod two-jointed, with flagelliform distal article. Male pleopod 2 endopod with two thickset articles, distal one tapering apically.

Etymology.

The genus is named after Dr Flavio Chaimowicz, a physician who provided important contributions for the Brazilian speleology. Gender feminine.

Remarks.

The diagnosis of Styloniscinae , Notoniscinae and Kuscheloniscinae has been presented in old publications that unfortunately include few characters of their members ( Vandel 1952; Strouhal 1961). Meanwhile, more details have been provided for Iuiuniscinae ( Souza et al. 2015). According to Vandel (1952: 95), Styloniscinae exhibit i. body smooth or tuberculated, without longitudinal ribs, and ii. pleon-epimera 1-5 narrow, with a gap between the pereon and pleon. For Notoniscinae , Vandel (1952: 95-96) noted i. pereonites dorsum tuberculated or with longitudinal ribs (sometimes with conspicuous protuberances also on the pleonites); ii. pleon-epimera 3-5 or 4-5 well developed, reducing the gap between the pereon and pleon; iii. genital tract of styloniscid type; iv. eyes with 3 ommatidia. For Kuscheloniscinae Strouhal (1961: 217) indicated the following: i. outline of pleon continuous with that of pereon; ii. pleon-epimera 3-5 very reduced; iii. anterior pereonites with protuberances and lateral ribs. Finally, Iuiuniscinae are characterized by i. dorsal integument smooth or without ribs or large protrusions; ii. enlarged epimera; iii. pereopod 1 much shorter than the others flanking the head; iv. pleon-epimera forming acute tips; v. telson distal half lower than the proximal half, and vi. habit to build mud shelters to molt and to protect juveniles ( Souza et al. 2015). Chaimowiczia gen. nov. can be promptly distinguished from all the already described Styloniscidae by the pronounced rectangular-shaped lateral projections of pereonites, which is not observed in other members of this family. Moreover, tubercles are absent and the body outline is continuous without a gap between pereon and pleon. Epimera are developed in pleonites 3 to 5 forming tips, and telson distal half is narrower than the proximal half. Based on these characters, Chaimowiczia gen. nov. was allocated into the subfamily Iuiuniscinae .

Chaimowiczia gen. nov., as well as Iuiuniscus , occurs in the São Francisco River Basin and the caves are in the limestone plateaus of the Bambuí Group ( Auler et al. 2001) (Fig. 1 ). The new genus resembles Iuiuniscus by the widely separated pereonites 1-7 epimera directed outwards, pleonites 3-5 epimera well developed; mandibles pars molaris large and projected. However, Chaimowiczia gen. nov. is not able to build mud shelters as Iuiuniscus. These genera also differ in the number of aesthetascs in antennula distal article ( Iuiuniscus 12 Iuiuniscus versus 2 in Chaimowiczia gen. nov.), in the number of articles in antennal flagellum ( Iuiuniscus 8 Iuiuniscus versus 3 in Chaimowiczia gen. nov.), teeth morphology in the maxillula outer ramus (outer group with curved teeth in Iuiuniscus versus straight in Chaimowiczia gen. nov.; inner group with two longer teeth in Iuiuniscus versus subequal in Chaimowiczia gen. nov.), male pleopod 1 exopod and endopod proportion (exopod longer than endopod in Chaimowiczia gen. nov. Iuiuniscus versus the opposite in Iuiuniscus ), shape of male pleopod 1 exopod, shape of male pleopod 2 exopod (triangular in Iuiuniscus versus semicircular in Chaimowiczia gen. nov.), and notably by the morphology of pereon and pleon (with very prominent and very acute tips in pereon and pleon epimera in Iuiuniscus Iuiuniscus versus not so prominent nor so acute tips in Chaimowiczia gen. nov.).

Figures

Figure 1. South America with the distribution of Chaimowiczia gen. nov. and Iuiuniscus. Delimited area in the states of Minas Gerais and Bahia states with the karst area of the Bambui Group are represented in gray, rivers from Sao Francisco River Basin are represented in blue.