Atlantasellus Sket, 1979

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Suggested Common Name: Pillslaters
Number of subordinate taxa: 2 species, endemic to our area
Etymology: Atlantic + Asellus, after the location of this genus' first species on Bermuda in the middle of the Atlantic. Common name refers to the odd combination of traits this genus has, with the conglobulating ability combined with the asellote-like (="slater") general morphology
Taxonomic History: Atlantasellus Sket, 1979
Size Range: to 2.14mm
Description: Body ovate, subcylindrical, conglobulating. Head frontal margin tridentate, valleys cupping antenna 1 bases. Eyes absent. Antenna 1 peduncle segments 1-2 expanded, segment 1 cup-shaped, segment 2 wider than long; flagellum contributing to conglobulation.  Antennae 2 scale absent. Maxilliped basis tip weakly trilobed. Pereopod 1 prehensile. Pereopods 2-7 with 2 claws. Pereopods 2-4 coxae free, elongate. Pereonites 5-7 coxae completely fused to form coxal plates. ♂ pleopod 1 present, not fused, protopod very short and wide, endite long and narrow. Pleopod 4 biramous, rami subequal in size. Pleopod 5 consisting of a single ovate plate. Telson ovate, notched at tip between uropod insertions, base of notch with tooth or convex. Uropods vestigial, unsegmented.
Type taxon: Atlantasellus cavernicolus Sket, 1979
Notes: As with the family, the one and only published description of this genus was in Sket, 1979. A fuller diagnosis consisting of features shared between the two known species is included here
Both species in this genus are cavernicolus, with one species currently listed as Critically Endangered and the other likely to be endangered in some way or form by its minute range.

Subordinate taxa: Atlantasellus cavernicolus, Atlantasellus dominicanus

Key to species
1 a. Posterolateral corners of head stout, triangular; left mandible spine row with 2 spines; pereopod 5 uniramous; telson corners far surpassing uropods, tip pointed; pleopod 3 with sclerotized ridges; pleopod 4 exopod longer than endopod; Bermuda --> Atlantasellus cavernicolus
b. Posterolateral corners of head extended, sickle-shaped; left mandible spine row with 3 spines; pereopod 5 with a rudimentary exopod; telson corners not extending past uropods, tip rounded; pleopod 3 without sclerotized ridges; pleopod 4 exopod shorter than endopod; Hispaniola --> Atlantasellus dominicanus

Sources

Jaume, D. (2001). A new atlantasellid isopod (Asellota: Aselloidea) from the flooded coastal karst of the
Dominican Republic (Hispaniola): evidence for an exopod on a thoracic limb and biogeographical
implications. Journal of Zoology, 255(2), 221-233.

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

Wägele, J. W. (1983). On the origin of the Microcerberidae (Crustacea: Isopoda). Journal of Zoological Systematics and Evolutionary Research, 21(4):249-262.

Published: Feb 15, 2023