Circoniscus mendesi Lopez-Orozco, Campos-Filho & Bichuette 2024, sp. nov.
Creators: name: López-Orozco, Carlos Mario
name: Campos-Filho, Ivanklin Soares
name: Gallo, Jéssica S.
name: Gallão, Jonas E.
name: Carpio-Díaz, Yesenia M.
name: Borja-Arrieta, Ricardo
name: Bichuette, Maria Elina
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Scleropactidae
Circoniscus
Circoniscus mendesi

description: Circoniscus mendesi López-Orozco, Campos-Filho & Bichuette sp. nov.
urn:lsid:zoobank.org:act: 5AEA1F23-397B-4C4B-A423-3659311F11C8
Figs 1–4, 8A–B
Diagnosis
Pigment and eyes absent; schisma on pereonite 1 and ventral triangular lobe in pereonite 2; antennula bearing eight lateral aesthetascs arranged in three sets; pleopod 1 and 2 exopods with respiratory areas; pereopod 7 merus bearing triangular lobe on rostral portion; pleopod 5 exopod apex elongated and acute.
Etymology
The new species is named after Francisco Alves Mendes Filho, popularly known as Chico Mendes, a rubber tapper and activist who gained an international reputation for the defense of the Amazonian biodiversity. Furthermore, the present name honors all workers of the ICMBio (in Portuguese, Instituto Chico Mendes de Conservação da Biodiversidade), who continue to keep alive Mendes’ ideals.
Material examined
Holotype
BRAZIL – Pará, Parauapebas • ♂; CAV-N1-0174; 6°01′27.20″ S, 50°17′54.73″ W; 649 m a.s.l.; 22 Aug. 2021; M.E. Bichuette, J.E. Gallão and D.F. Torres leg.; LES 0028767.
Paratypes
BRAZIL – Pará, Parauapebas • 1 ♂, 1 ♀; same collection data as for holotype; part in micropreparations; LES 0028768 • 3 ♂♂, 4 ♀♀; same collection data as for holotype; LES 0028769 • 1 ♂, 1 ♀; same locality as for holotype; 12 Feb. 2022; J.E. Gallão, J.S. Gallo, D.F. Torres and V.F. Sperandei leg.; LES 0028770 • 3 ♂♂; same collection data as for preceding; LES 0028771.
Description
MEASUREMENTS. Maximum body length: male 5 mm, female 6 mm.
BODY. Color pale yellowish, with typical muscle spots insertions. Exoantenal conglobation (Fig. 2A); body strongly convex (Fig. 2A); dorsal surface smooth, bearing small triangular scale-setae (Fig. 2B). Noduli laterales not discernible at 400× magnification.
CEPHALON. Wider than long, frontal shield obtuse on medial upper margin and straight lateral margins, lateral lobes and eyes absent (Fig. 2C–E).
PEREON. Pereonite1 epimera with schisma, anterior corners directed frontwards (Fig.2A,E–F); pereonite 2 with ventral triangular lobes, epimera with outer margin rounded (Fig. 2A, E–F); pereonites 3–4 epimera with outer margin rounded (Fig. 2A); pereonites 5–7 epimera subquadrangular (Fig. 2A).
PLEON. Pleonites 3–5 epimera with outline continuous with that of pereonite 7, apex acute and directed backwards (Fig. 2G); telson triangular, slightly broader than long, with slightly concave sides, rounded apex (Fig. 2G).
ANTENNULA. Composed of three articles, distal article longest and conical, bearing eight lateral aesthetascs arranged in three sets and apical tip (Fig. 2H).
ANTENNA. Short and stout, not surpassing pereonite 1 when extended backwards; flagellum consisting of two subequal articles, distal article bearing seven lateral aesthetascs in two groups; apical organ longer than distal article of flagellum (Fig. 2I).
MOUTH. Mandibles with molar penicil of many branches; left mandible (Fig. 3A) with 2+1 free penicils, right mandible (Fig. 3B) with 1 + 1 penicils. Maxillula (Fig. 3C) inner endite with two apical penicils, distal margin bearing outer tip; outer endite with 5+ 5 teeth, inner set with four teeth apically cleft. Maxilla (Fig. 3D) inner lobe rounded and covered with thick setae; outer lobe about twice as wide as inner lobe, covered with thin setae. Maxilliped (Fig. 3E) basis rectangular bearing sparse scale-setae; palp with one setae on proximal article, medial and distal articles with two tufts of setae; endite subrectangular, medial seta long, surpassing distal margin, distal margin covered with thin setae and bearing one seta on outer portion, rostral surface with setose sulcus ending with one short penicil.
UROPOD. Protopod flattened and enlarged, filling gap between pleonite 5 and telson, surpassing distal margin of telson; exopod inserted on median margin, endopod twice as long as exopod and inserted proximally (Fig. 3F).
PEREOPOD 1. Carpus short, transverse antennal grooming brush; dactylus with inner claw surpassing median portion of outer claw, ungual seta and dactylar organ simple, surpassing distal margin of outer claw (Fig. 4A).
PLEOPOD EXOPODS. Pleopod 1 and 2 exopods with respiratory areas.
Male
PEREOPOD 1. Without particular modifications (Fig. 4A).
PEREOPOD 7. Ischium elongated, sternal margin straight; merus bearing triangular lobe on rostral portion (Fig. 4B).
GENITAL PAPILLA. Triangular ventral shield and subapical orifices (Fig. 4C).
PLEOPODS. Pleopod 1 (Fig. 4C) exopod ovoid; endopod about twice as long as exopod and bent outwards, apex acute and bearing small setae along inner margin. Pleopod 2 (Fig. 4D) exopod triangular, outer margin concave with one seta; endopod flagelliform, longer than exopod. Pleopod 3–4 exopods as in Fig. 4E–F. Pleopod 5 (Fig. 4G) exopod triangular, outer margin almost straight with one tiny setae, inner margin covered with small setae, apex elongated and acute.
Taxonomic remarks
The genus Circoniscus comprises 11 species with a distribution restricted to South America (Schmidt 2007; Campos-Filho et al. 2017, 2018, 2023; Ocampo-Maceda et al. 2022). To date, except for Circoniscus pallidus Arcangeli, 1936, in the State of São Paulo, and Circoniscus caeruleus Campos-Filho, Sfenthourakis & Bichuette, 2023, in the state of Mato Grosso, all species are recorded from the State of Pará (Campos-Filho et al. 2018, 2023). The genus was morphologically defined by Schmidt (2007). Among the species of the genus, Circoniscus buckupi Campos-Filho & Araujo, 2011 and C. carajasensis Campos-Filho & Araujo, 2011 are considered troglobitic, with records from several caves in the State of Pará (Campos-Filho & Araujo 2011; Campos-Filho et al. 2022c).
In the absence of body pigments and eyes, C. mendesi sp. nov. is similar to C. buckupi and C. carajasensis; however, it can be distinguished by the triangular sternal lobe of the male pereopod 7 merus, and male pleopod 5 exopod acute. The triangular steral lobe on the merus 7 is also present in the species of Circoniscus in the paper of Campos-Filho et al. (2023) from Gruta Lagoa Azul, Bonito, State of Mato Grosso; however, this species is considered to be a troglophilic with characters easily distinguishable from Circoniscus mendesi sp. nov.
Ecological remarks
The specimens were collected in the twilight zone, living under rocks, in leaf litter, between roots, and in moist soil (Fig. 11A–B). This species is considered to be troglobitic due to the absence of body pigments and eyes and to the presence of elongated pereopods.
Distribution
Presently known only from N1_0174 cave, FLONA de Carajás, Parauapebas, Pará, Brazil (Fig. 1).
description: Published as part of López-Orozco, Carlos Mario, Campos-Filho, Ivanklin Soares, Gallo, Jéssica S., Gallão, Jonas E., Carpio-Díaz, Yesenia M., Borja-Arrieta, Ricardo & Bichuette, Maria Elina, 2024, Iron-isopods: new records and new species of terrestrial isopods (Isopoda, Oniscidea) from Brazilian Amazon iron ore caves, pp. 116-135 in European Journal of Taxonomy 921 (1) on pages 120-125, DOI: 10.5852/ejt.2024.921.2421, http://zenodo.org/record/10623397