Rhicnosthetus chagasi, Bouzan & Iniesta & Brescovit, 2021

Bouzan, Rodrigo Salvador, Iniesta, Luiz Felipe Moretti & Brescovit, Antonio Domingos, 2021, Periclimenaeus djiboutensis Bruce 1970, Zoological Studies 60 (21), pp. 1-14 : 4-11

Rhicnosthetus coriaceus ( Schubart, 1947) ( Figs. 4–5 , 11 )

Leptodesmus coriaceus Schubart, 1947: 11 , figs. 10–11 (syntypes: 10 males, 10 females and 6 juveniles from Santa Terezinha, (-10.471803°; -50.515290°), formerly Barra do Tapirapé, Mato Grosso, Brazil, 23.XI.1939 − 15.III.1940, A. L. de Carvalho coll., deposited in MZSP and MNRJ). Only 2M and 2F deposited in MZSP, and 3M 2F deposited in MNRJ were examined (male lectotype, MNRJ 11812, and all remaining material as paralectotypes are here designated).

Rhicnosthetus coriaceus : Hoffman, 2006: 55, figs. 26–27.

Diagnosis: Males of R. coriaceus differ from all other species of the genus based on the combination of gonopodal characteristics: prefemoral process robust and reaching half the size of the acropodite ( Fig. 4a ) and acropodital process not exceeding the size of the solenomere ( Fig. 4d ).

Descriptive notes on females: (Paralectotype, MNRJ 11625). Pair of legs on body ring 3 with the coxae possessing a small process. Posterior margin of the vulvae aperture smooth, without projections ( Fig. 8b ). Vulvae rounded shaped in ventral view ( Fig. 5a ) and elliptical shaped in lateral view ( Fig. 5b ). Apical region with the intermediate membrane elevated ( Fig. 5d ) and medial region with a small aperture ( Fig. 5c ), ventral view. Total length: 55.41. Total width: 8.35. Posterior margin of the vulvae aperture: 1.59 width. Vulvae: length 0.75, width 0.50. External valve: length 0.62, width 0.32. Internal valve: length 0.48, width 0.24. Operculum: length 0.28, width 0.42. External valve (EV, Fig. 5a, 5d ) bigger; with long and scattered setae in comparison of the internal valve (IV, Fig. 5a, 5d ). Operculum large and densely covered by setae (OP, Fig. 5a–b ).

Distribution: Known only from the state of Mato Grosso, Brazil ( Fig. 11 ).

Rhicnosthetus chagasi sp. nov. ( Figs. 1–2 , 6–8 , 11 ) urn:lsid:zoobank.org:act:861C83D6-EBD8-445D-B56D-3FCCF84BFE47

Material examined: Male holotype and female paratype from Chácara dos Idosos, Cotriguaçu (-9.901695°; -58.570062°), Mato Grosso, Brazil, deposited in IBSP 7782 and IBSP 7783, respectively. Non-types: BRAZIL. Mato Grosso: Cotriguaçu (-9.901695°; -58.570062°), Chácara dos Idosos, no data and collector, Mato Grosso, Brazil, 2M and 1F (CZUFMT MYR 851); Fazenda São Nicolau, 13.XII.2009, L. D. Battirola coll., 4M and 3F (IBSP 5366).

Etymology: The specific epithet is a patronym in honor of Dr. Amazonas Chagas Júnior, for his friendship and several contributions to our knowledge of Myriapods in Brazil.

Diagnosis: Males of R. chagasi sp. nov. differ from all other species of the genus based on the combination of gonopodal characteristics: prefemoral process slender and reaching half the size of the acropodite ( Fig. 6d ) and a falciform acropodital process exceeding the size of the solenomere ( Fig. 6f ).

Description: Male (Holotype, IBSP 7782). Coloration in life: head reddish brown. Antennae with yellow and brown antennomeres. Body dark brown, with the paranota tip yellow ( Fig. 1 ); (long-preserved in 70% ethanol): Head ocher with the apex brown. Antennae yellowish. Body light brown and paranota tip yellowish ( Fig. 6a–c ). Body rings: cuticle with microgranular texture ( Fig. 2b ); paranota rectangular with posterior edges slightly produced ( Fig. 2a ); ozopore central-posteriorly situated on paranota ( Fig. 2a ). Stigma oval. Sternites with podosterna rough (= longitudinally striated – Hoffman, 2006) ( Fig. 2c ). Sternite of body ring 4 with a pair of small rounded projections appressed against each other. Sternite of all the body rings with two pairs of small rounded projections ( Fig. 2c ). Pair of legs on body ring 3 with coxae possessing a rectangular-shaped gonapophysis. Gonopod aperture on seventh body ring oval, posterior edge without any modifications. Legs yellowish, without modifications, with scattered thin setae ( Fig. 2d ). Telson with the same color as the body. Total length: 54.60. Total width: 8.04. Collum, length, 1.88, width, 6.81. Antennomere lengths (1> 7): 0.65; 1.39; 1.38; 1.43; 1.29; 1.37 0.35. Podomeres lengths (1> 7): 0.66; 0.95; 2.38; 0.77; 0.84; 1.47; 0.45. Gonopod aperture, length 0.94, width 1.81 Telson, length 1.57. Gonopod: length 2.11, width 1.72. Coxae: length 0.74, width 1.00. Telopodite: length 2.11, width 0.80.

Gonopods ( Figs. 6d–f , 7a–d ): coxae equivalent to about half the length of the telopodite and prominently rounded in ectal view ( Figs. 6f , 7c ). Coxae with two setae on the distal dorsal side. Presence of small spiniform process hidden by the coxa in mesal view (SP; Fig. 6d ). Cannula: hook-shaped. Prefemoral region long, 1/2 length of telopodite. Prefemoral process long and slim, with the apical region curved and reaching half the length of the acropodite (PfP; Figs. 6d , 7a ). Prefemoral process with a reduced small spine in the medial region of the process. Acropodite elongated and robust; composed of a large and concave lobe on dorsal side conducting the seminal groove along its edge (SG; Fig. 6d, f ); and distal and falciform acropodital process (AP; Fig. 6d, f ). Solenomere and acropodital process close to the apical region of the acropodite ( Fig. 6d–f ).

Female (Paratype, IBSP 7783). Body as in male. Pair of legs on body ring 3 with the coxae possessing a small, blunt process ( Fig. 8a ). Posterior margin of the vulvae aperture smooth, without projections ( Fig. 8b ). Vulvae rounded shaped in ventral view ( Fig. 8c ) and elliptical shaped in lateral view ( Fig. 8d ). Apical region with a large aperture ( Fig. 8f ) and medial region with a small aperture ( Fig. 8e ), ventral view. Total length: 54.72. Total width: 7.78. Posterior margin of the vulvae aperture: 1.73 width. Vulvae: length 0.77, width 0.573. External valve: length 0.51, width 0.24. Internal valve: length 0.54, width 0.18. Operculum: length 0.24, width 0.38. External valve (EV, Fig. 8c–d ) with long and scattered setae in comparison of the internal valve (IV, Fig. 8c–d ). Operculum large and densely covered by long setae; small setae restricted in the centro-apical part (OP, Fig. 8c–d ).

Distribution: The species is known from the region of Cotriguaçu, state of Mato Grosso, Brazil ( Fig. 11 ).

Rhicnosthetus penabarbosai sp. nov. ( Figs. 9–11 ) urn:lsid:zoobank.org:act:D500C918-01ED-40FF-9764-4937B79B1A7F

Material examined: Male holotype and male paratype from Chapada dos Parecis (-14.339394°; - 56.39202°), Diamantina, Mato Grosso, Brazil, XI.1993, D. Novaes & R. Pardini coll., deposited in IBSP 7784 and IBSP 7785, respectively.

Etymology: The specific epithet is a patronym in honor of Dr. João Paulo P. Pena Barbosa, for his outstanding contributions to our knowledge concerning the Chelodesmidae , and for his friendship and advice over the years.

Diagnosis: Males of R. penabarbosai sp. nov. differ from all other species of the genus by having the prefemoral process as long as the acropodite ( Figs. 9d– f , 10a–d ) and by having the solenomere and acropodital process divided at the base of the acropodital region ( Fig. 9e ).

Description: Male (Holotype, IBSP 7784). Coloration (long-preserved in 70% ethanol): Head ocher. Antennae yellowish ocher. Body ocher and paranota tip yellowish – not uniform throughout the body, probably due to ethanol depigmentation ( Fig. 9a–c ). Body rings: cuticle with microgranular texture; paranota rectangular with posterior edges slightly produced ( Fig. 9b ); ozopore central-posteriorly situated on paranota. Stigma oval. Sternites with podosterna smooth. Sternite of body ring 4 with a pair of small rounded projections appressed against each other. Sternite of all the body rings with two pairs of small rounded projections. Pair of legs on body ring 3 with coxae possessing a rectangular-shaped gonapophysis. Gonopod aperture on seventh body ring oval, posterior edge without any modifications. Legs yellowish ocher, without modifications, with scattered, thin setae. Telson with the same color as the body. Total length: 43.05. Total width: 6.04. Collum, length, 1.80, width, 5.70. Antennomere lengths (1> 7): 0.55; 1.31; 1.19; 1.05; 1.22; 1.21 0.25. Podomeres lengths (1> 7): 0.65; 0.75; 1.98; 0.63; 0.86; 1.23; 0.37. Gonopod aperture, length 0.74, width 1.35 Telson, length 1.16. Gonopod: length 1.66, width 1.27. Coxae: length 0.51, width 0.98. Telopodite: length 1.55, width 0.52.

Gonopods ( Figs. 9d–f , 10a–d ): coxae equivalent to about half the length of the telopodite and prominently rounded in ectal view ( Figs. 9f , 10c ). Coxae with two setae on the distal dorsal side. Presence of small spiniform process hidden by the coxae in mesal view (SP; Fig. 10a ). Cannula: hook-shaped. Prefemoral region long, 1/2 length of telopodite. Prefemoral process long and slender, with the apical region curved and as long as the solenomere (PfP; Fig. 9d–f ). With small spine in the medial region of the process. Acropodite elongated and slender in comparison with the other species of the genus; consisting of a reduced concave process without a lobe and conducting the seminal groove along its edge on dorsal side (SG; Fig. 10d ) and distal, slender and falciform acropodite process (AP; Figs. 9d–f , 10c–d ). Solenomere and acropodital process divided at the base of the acropodital region ( Fig. 9e ). Solenomere with a broad large apex ( Fig. 10b ).

Female: Unknown.

Distribution: The species is known only from the type locality ( Fig. 11 ).

Figures

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. 5. Rhicnosthetus coriaceus (MNRJ 11625), left vulva. (a) ventral view; (b) latero-ventral view; (c) detail of the medial region, ventral view; (d) detail of the apex, ventral view. Scale bars: a = 300 µm; b = 400 µm; c–d = 100 µm. Abbreviations: EV, external valve; Op, operculum; IV, internal valve.

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

Fig. 8. Rhicnosthetus chagasi sp. nov. (CZUFMT MYR 851), female. (a) Legs of body ring 3, lateral view; (b) posterior margin of the vulvae aperture; (c) ventral view; (d) lateral view; (e) detail of the medial region, ventral view; (f) detail of the apex, ventral view. Scale bars: a = 1 mm; b = 500 µm; c–d = 400 µm; e–f = 100 µm. Abbreviations: EV, external valve; Op, operculum; IV, internal valve.

Fig. 1. Live male specimen of Rhicnosthetus chagasi sp. nov., from Fazenda São Nicolau, Cotriguaçu, Mato Grosso, Brazil. Photographed by: Dr. Domingos de Jesus Rodrigues.

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.