Paratrichorhina, Bezerra-Pereira & Grangeiro & Lima, 2023

Bezerra-Pereira, Carlos Anderson Soares, Grangeiro, Daniela Correia & Lima, Lucas Ramos Costa, 2023, A new genus and two new species of Platyarthridae Verhoeff, 1949 (Crustacea: Isopoda: Oniscidea) from Brazil, Zootaxa 5325 (3), pp. 436-450 : 437-438

Paratrichorhina n. gen.

Type species. Paratrichorhina piauiensis n. sp., by present designation.

Diagnosis. Animals with dorsal habitus narrow; dorsal surface covered with fan shaped scale-setae; cephalothorax with suprantennal line, frontal line absent, eyes with reduced number of ommatidia; pereonites epimera with one line of noduli laterales per side, glandular pores not visible; pleotelson triangular with apex acute; first antenna three-jointed with aesthetascs; second antenna with flagellum of two articles, distal article 3–4 times higher than basal; mandibles molar with penicil dichotomized; outer endite of the first maxilla bearing pectinate teeth; second maxilla bilobate; maxilliped basis with some conspicuous setae and sulcus lateralis and palp with two setae on proximal article; pleopod exopods without respiratory areas.

Etymology. Greek ‘pará’ = beside, near + Trichorhina . The new genus name refers to morphological similarities with the genus Trichorhina .

Remarks. The family Platyarthridae is recognized by the following characteristics: animals not exceeding 6 mm long; dorsal surface with fan shaped scale-setae; first antenna three-jointed; second antenna with flagellum of two articles, with basal article much shorter than apical one; suprantennal line present; small noduli laterales present; pleopods exopods without respiratory area; telson triangular and inability to roll up ( Schmidt 2003; Javidkar et al. 2015). Paratrichorhina n. gen. was allocated to the family Platyarthridae because it exhibits these characters.

This genus is erected based on the presence of pectinate teeth on the outer endite of the first maxilla, absent in the following genera: Platyarthrus , Gerufa , Papuasoniscus , Lanceochaetus , Echinochaetus and Cephaloniscus . However, in Platyarthridae , two genera have species with this characteristic: in Niambia the subgenus Manibia Barnard, 1932 and Trichorhina , nevertheless, the presence of these species in cited genus is doubtful (see General discussion).

The species of Paratrichorhina n. gen. differ from the species of Niambia by the following: 1. N. (Manibia) lata : a) cephalothorax barely involved by pereonite 1 (vs. completely involved); b) second antenna, when extended backward, does not extend beyond the pereonite 1 (vs. surpassing); c) frontal line absent (vs. present); d) dorsal surface smooth (vs. granular); e) eyes with three ommatidia (vs. 10 ommatidia) f) outer endite of first maxilla with 4+5 teeth, four of them pectinated (vs. with 4+4 teeth, all pectinated); 2. N. (Manibia) microps : a) second antenna, when extended backward, does not extend beyond the pereonite 1 (vs. surpassing); b) frontal line absent (vs. present); c) dorsal surface smooth (vs. granular); d) eyes with three ommatidia (vs. six ommatidia); e) outer endite of first maxilla with 4+5 teeth, four of them pectinated (vs. with 4+4 teeth, all pectinated).

It differs from species in Trichorhina by: 1. T. micros : a) frontal line absent (vs. present); b) eyes with three ommatidia (vs. 3–4 ommatidia); c) a row of noduli laterales in pereonites I–VII (vs. double row); outer endite of first maxilla with 4+5 teeth, four of them pectinated (vs. with 5+4 teeth, one bifid and three pectinated); 2. T. minutissima : a) frontal line absent (vs. present); b) eyes with three ommatidia (vs. 6–7 ommatidia); c) a row of noduli laterales in pereonites 1–7 (vs. double row); outer endite of first maxilla with 4+5 teeth, four of them pectinated (vs. with 4+5 teeth, two bifid and three pectinated).