Circoniscus xikrin López-Orozco, Campos-Filho & Carpio-Díaz, 2024
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publication ID |
https://doi.org/ 10.5852/ejt.2024.921.2421 |
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publication LSID |
lsid:zoobank.org:pub:BE1232A7-064A-4D0C-B9BE-05559274B29D |
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DOI |
https://doi.org/10.5281/zenodo.10623427 |
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persistent identifier |
https://treatment.plazi.org/id/039B87F6-FF8D-181A-F25B-BA793BA6A272 |
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treatment provided by |
Plazi |
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scientific name |
Circoniscus xikrin López-Orozco, Campos-Filho & Carpio-Díaz |
| status |
sp. nov. |
Circoniscus xikrin López-Orozco, Campos-Filho & Carpio-Díaz sp. nov.
urn:lsid:zoobank.org:act:A22A4823-7BC1-428A-AE59-39C00021300B
Figs 1 View Fig , 5–7 View Fig View Fig View Fig
Diagnosis
Pigment and eyes absent; schisma on pereonite 1, pereonite 2 without ventral lobe; telson with acute apex; antennula bearing eleven lateral aesthetascs arranged in six sets; pleopod 1 and 2 exopods with respiratory areas; pereopod 7 ischium elongated, bearing semicircular lobe on rostral portion, merus bearing semicircular lobe on rostral portion; pleopod 5 exopod apex short and acute.
Etymology
The new species is named for the Xikrin native people, inhabitants of Terras Indígenas Cateté and Trincheira Bacajá, State of Pará.
Material examined
Holotype
BRAZIL – Pará, Canaã dos Carajás • ♂; SB_0049 cave (also registered as GEM 1460 and known as Samuel II by local people); 6°18′58.4″ S, 49°53′41.1″ W; 629 m a.s.l.; 16 Feb, 2022; J.E. Gallão, J.S. Gallo, D.F. Torres and V.F. Sperandei leg.; part in micropreparations; LES 0028772 About LES . GoogleMaps
Paratype
BRAZIL – Pará, Parauapebas • 1 ♀; N3_0026 cave; 6°02′40.3″ S, 50°13′10.6″ W; 18 Feb. 2022; same collectors as for holotype; LES 0028773 About LES GoogleMaps .
Description
MEASUREMENTS. Maximum body length: male 5.8 mm, female 6 mm.
BODY. Color pale yellowish, with typical muscle spots insertions. Exoantennal conglobation ( Fig. 5A View Fig ); body strongly convex ( Fig. 5A View Fig ); dorsal surface smooth, bearing small fan-shaped scale-setae ( Fig. 5B View Fig ). 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. 5C–E View Fig ).
PEREON. Pereonite 1 epimera with schisma, anterior corners directed frontwards ( Fig. 5A, E–F View Fig ); pereonite 2 without ventral lobes, epimera with outer margin rounded ( Fig. 5A, E–F View Fig ); pereonites 3–4 epimera with outer margin rounded ( Fig. 5A View Fig ); pereonites 5–7 epimera subquadrangular ( Fig. 5A View Fig ).
PLEON. Pleonites 3–5 epimera with outline continuous with that of pereonite 7, apex acute and directed backwards ( Fig. 5G View Fig ); telson triangular, broader than long, with slightly concave sides, acute apex ( Fig. 5G View Fig ).
ANTENNULA. Composed of three articles, distal article longest, conical, proximal portion protruding, bearing 11 lateral aesthetascs arranged in six sets plus apical tip ( Fig. 5H View Fig ).
ANTENNA. Short and stout, not surpassing pereonite 2 when extended backwards; flagellum consisting of two subequal articles, distal article bearing 17 lateral aesthetascs in two groups; apical organ short than distal article of flagellum ( Fig. 5I View Fig ).
MOUTH. Mandibles with molar penicil of seven branches; left mandible ( Fig. 6A View Fig ) with 2+ 1 free penicils, right mandible ( Fig. 6B View Fig ) with 1 + 1 penicils. Maxillula ( Fig. 6C View Fig ) inner endite with two apical penicils, distal margin bearing outer tip; outer endite with 4+ 6 teeth, inner set with four teeth apically cleft. Maxilla ( Fig. 6D View Fig ) inner and outer lobe rounded and covered with thick setae. Maxilliped ( Fig. 6E View Fig ) as in C. mendesi sp. nov.
UROPOD. Protopod flattened and enlarged, filling gap between pleonite 5 and telson, surpassing distal margin of telson; exopod inserted on median margin; endopod short, twice as long as exopod and inserted proximally ( Fig. 6F View Fig ).
PEREOPOD 1. Elongated, carpus short, transverse antennal grooming brush; dactylus with inner claw not surpassing median portion of outer claw, ungual seta, and dactylar organ simple not surpassing distal margin of outer claw ( Fig. 7A View Fig ).
PLEOPOD EXOPODS. Pleopod 1 and 2 exopods with respiratory areas.
Male
PEREOPOD 1. Without particular modifications ( Fig. 7A View Fig ).
PEREOPOD 7. Basis and ischium elongated, sternal margin straight, with one semicircular lobe on distal portion in rostral view; merus bearing semicircular lobe in proximal portion in rostral view ( Fig. 7B View Fig ).
GENITAL PAPILLA. Triangular ventral shield and subapical orifices ( Fig. 7C View Fig ).
PLEOPODS. Pleopod 1 ( Fig. 7C View Fig ) exopod ovoid, with semicircular apex; endopod about twice as long as exopod and bent outwards, apex acute and bearing small setae along inner margin. Pleopod 2 ( Fig. 7D View Fig ) exopod triangular, outer margin concave with one seta; endopod flagelliform, longer than exopod. Pleopod 3–4 exopods as in Fig. 7E–F View Fig , respectively. Pleopod 5 ( Fig. 7G View Fig ) exopod triangular, outer margin almost straight with one tiny seta, inner margin covered with small setae, apex short and acute.
Taxonomic remarks
Circoniscus xikrin sp. nov. is clearly distinguishable from C. buckupi , C. carajasensis , and C. mendesi sp. nov. in the semicircular lobe on the rostral surface of the male pereopod 7 ischium and merus, and telson with acute apex.
Ecological remarks
The specimens were collected in the aphotic zone, inhabiting very moist soil. This species is considered to be a troglobitic due to the absence of body pigments and eyes, and elongated pereopods.
Distribution
Presently known only from SB_0049 cave in PARNA dos Campos Ferruginosos, Canaã dos Carajás, and N3_0026 cave system, Parauapebas, Pará, Brazil ( Fig. 1 View Fig ).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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