Polydesmida Pocock, 1887

Bouzan, Rodrigo Salvador, Iniesta, Luiz Felipe Moretti & Brescovit, Antonio Domingos, 2021, Periclimenaeus djiboutensis Bruce 1970, Zoological Studies 60 (21), pp. 1-14 : 2-3

Order Polydesmida Pocock, 1887 Suborder Leptodesmidea Brölemann, 1916 Family Chelodesmidae Cook, 1895 Subfamily Chelodesminae Cook, 1895 Genus Rhicnosthetus Hoffman, 2006

Rhicnosthetus Hoffman, 2006: 43–55 .

Type species: Rhicnosthetus rondoni Hoffman,

2006, by original designation.

Diagnosis: Males of Rhicnosthetus differ from those of other chelodesmid genera by the combination of the following characters: microgranular tergal texture ( Fig. 2a–b ), seminal groove running along a broad lobe on the acropodite ( Figs. 6e , 7a, c–d ) (reduced in R. penabarbosai sp. nov.; Figs. 9e , 10a, c–d ), small spine in the median region of the prefemoral process ( Fig. 4a– b ) (reduced in R. chagasi sp. nov.; Figs. 6d , 7a ) and a hook-shaped acropodital process ( Fig. 3a–b ).

Distribution: Known from the Brazilian states of Rondônia and Mato Grosso ( Fig. 11 ).

Composition: Four species, Rhicnosthetus rondoni , R. coriaceus , R. chagasi sp. nov. and R. penabarbosai sp. nov.

Figures

Fig. 2. Male of Rhicnosthetus chagasi sp. nov. (CZUFMT MYR 851). (a) Paranota, dorsal view; (b) Detail of the microgranular tergal texture; (c) sternite of body ring 9 in ventral view; (d) leg (7th leg pair) in lateral view. Scale bars: a, c = 1 mm; b = 300 µm; d = 2 mm.

Fig. 6. Rhicnosthetus chagasi sp. nov. (holotype, IBSP 7782), dorsal view of anterior (a), midbody (b) and posterior (c) body rings. Scale bars = 2 mm. Left gonopod. (d), mesal view; (e), ventral view; (f), ectal view. Scale bars: 1 mm. Abbreviations: AP, acropodital process; PfP, prefemoral process; SG, seminal groove; SP, spiniform process.

Fig. 7. Rhicnosthetus chagasi sp. nov. (CZUFMT MYR 851), left gonopod. (a) mesal view; (b) detail of the acropodite, mesal view; (c) ectal view; (d) detail of the acropodite and prefemoral process, ectal view. Scale bars: a–c = 500 µm; d = 400 µm. Abbreviations: AP, acropodital process; PfP, prefemoral process; S, solenomere; SG, seminal groove; SP, spiniform process.

Fig. 9. Rhicnosthetus penabarbosai sp. nov. (holotype, IBSP 7784), dorsal views of anterior (a), midbody (b) and posterior (c) body rings. Scale bars = 2 mm. Left gonopod. (d), mesal view; (e), ventral view; (f), ectal view. Scale bars: 1 mm. Abbreviations: AP, acropodital process; PfP, prefemoral process; SG, seminal groove; SP, spiniform process.

Fig. 10. Rhicnosthetus penabarbosai sp. nov. (paratype, IBSP 7785), left gonopod. (a) mesal view; (b) detail of the acropodite and prefemoral process, mesal view; (c) ectal view; (d) detail of the acropodite and prefemoral process, ectal view. Scale bars: a–b = 500 µm; c = 400 µm; d = 300 µm. Abbreviations: AP, acropodital process; PfP, prefemoral process; S, solenomere; SG, seminal groove; SP, spiniform process.

Fig. 4. Rhicnosthetus coriaceus (MNRJ 11625), left gonopod. (a) mesal view; (b) detail of the acropodite and prefemoral process, mesal view; (c) ectal view; (d) detail of the acropodite and prefemoral process, ectal view. Scale bars: a–c = 500 µm; d = 400 µm. Abbreviations: AP, acropodital process; PfP, prefemoral process; S, solenomere; SG, seminal groove; SP, spiniform process.

Fig. 3. Rhicnosthetus rondoni (CZUFMT MYR 864), left gonopod. (a) mesal view; (b) detail of the acropodite and prefemoral process, mesal view; (c) ectal view; (d) detail of the acropodite and prefemoral process, ectal view. Scale bars: a, c–d = 500 µm; b = 400 µm. Abbreviations: AP, acropodital process; PfP, prefemoral process; S, solenomere; SG, seminal groove; SP, spiniform process.

Fig. 11. Distribution map of Rhicnosthetus species. Symbols: triangles: R. rondoni; square: R. coriaceus; circle: R. chagasi sp. nov.; cross: R. penabarbosai sp. nov.