Atlantasellus cavernicolus Sket, 1979

Main Page | Isopoda > Microcerberidea > Atlantasellidae > Atlantasellus > Atlantasellus cavernicolus

Suggested Common Name: Bermuda Pillslater
Etymology: cavernicola = cave-dwelling [Latin], refering to the cave-dwelling habits of this species. Common name refers to this species' range, being endemic to the isolated island of Bermuda
Taxonomic History: Atlantasellus cavernicolus Sket, 1979
Size Range: to about 1.1mm
Description: (modified from Sket, 1979) Body somewhat elongate, domed, conglobulating, translucent, very sparsely setose. Head large; frontal margin tridentate with a triangular rostrum and triangular anterolateral lobes “cupping” antenna 1 bases. Antenna 1 half as long as head, flattened, sparsely setose, segments 1-2 lateral margin with thin lamella, segment 1 cup-shaped, segment 2 wider than long, segments 3-4(-5) subsequentally smaller. ♂ antenna 1 5-segmented with 4 flagellar aesthetascs. ♀ antenna 1 4-segmented with 2 flagellar aesthetascs. Antenna 2 “normal”, about 2x longer than antenna 1. Mandible incisor tip simple, slightly concave; lacinia fan-shaped, tip serrated; molar long, brush-like, divided into 4 setae distally; palp long, segment 2 longer than others, segment 3 with distal row of 7 setae. Maxilla 1 exopod with 9 unequally long distal setae; endopod short with 1 long distal seta. Maxilla 2 exopod bifid, both lobes with 2-3 long serrate setae; endopod with 1(-2) serrate seta(e). Maxilliped basis distal margin crenate, with thin narrow marginal lamella, distomedially with 2 linking hooks; palp medial margin with thin lamella. Pereonites 1-7 epimera vertical, broadly rounded distally. Pereopod 1 propus round-triangular, much longer than wide, palm with 1 proximal smooth spine and 3 more distal unimarginally serrate spines; merus and ischium short; basis long. Pereopods 2-7 subsimilar (pereopod 2 slightly shorter), slender, sparsely setose, segments cylindrical; dactyl 2-clawed. Pereopods 2-4 carpus with dorsodistal comb-shaped thickened seta. Pleonites 1-2 a bit shorter than pereonites with similar epimera. ♂ pleopod 1 protopod short, very broad, apically slightly lobed; endite long, narrow, set medially on protopod, with 1 plumose and 1 simple apical seta. ♂ pleopod 2 as long as pleopod 1; protopod nearly cylindrical, longer than wide; exopod minute, apparently 2-segmented; endopod proximally cylindrical, partially wrapped in a folded lamella, distally opened by a wide notch, laterally with small hooks. Pleopod 3 round-triangular proximally, sclerotized with prominent keels and edges with a few distolateral setae. Pleopod 4 rami subequal, subparallel; exopod with a distal suture and a proximolateral notch (remnants of a suture?), with 3 distomarginal plumose setae; endopod with 3 distomarginal setae. Pleopod 5 a simple uniramous plate. Telson elongate-semicircular, margins curved downward (inwards distally); tip tridentate from uropod insertions, central tooth acute. Uropod minute, ovoid, uniarticulate, with several setae. Anus subterminal, outside branchial chamber.
Geographic Range: Endemic to Bermuda, only known from a few caves in the northeastern part of the main island (the type specimen being recorded from Walsingham Sink Cave).
Notes: This species is listed on the IUCN Red List as Critically Endangered due to habitat degradation. Chemical and sewage leakages in the residental areas above the few caves where A. cavernicolus occur are the main concerns for the conservation of this species.
The only other species in the genus, A. dominicanus, does not co-occur with A. cavernicolus and has an exopod on pereopod 5, see the key for details.

Sources

Sket, B. (1979). Atlantasellus cavernicolus n. gen., n. sp. (Isopoda Asellota, Atlantasellidae n. fam.) from Bermuda. Biol, vestn. (Ljubljana), 27(2),175-183.

Iliffe, T.M. 1996. Atlantasellus cavernicolus. The IUCN Red List of Threatened Species 1996: e.T2355A9435213. https://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T2355A9435213.en. Accessed on 15 January 2023.

Published: Feb 15, 2023