Other Common Names
Hoglice (some Eurasian species)
Numbers
over 350 species globally; in our area about 126 described species and numerous (at least 25 known and countless unknown) undescribed species in 10 genera
Identification
Key to Asellid genera of North America:
1a. Eastern and Great Plains → 2
1b. Montane and Pacific → 5
2a. Head with large lateral plates, often with a large notch in the sides; pleopod 3 with an oblique suture; epigean. stygobitic and phreatobitic → Lirceus
2b. Head lacking large lateral plates; pleopod 3 usually with a transverse suture (oblique in some Lirceolus) → 3
3a. Pereopod 1 ambulatory, pereopods 2-3 strongly natatory and hairy; N FL stygobite → Remasellus parvus (monospecific genus)
3b. Pereopod 1 subchelate (at least in ♂’s), pereopods 2-3 ambulatory and not as hairy →
4a. ♂ pleopod 2 exopod lacking plumose setae or catch lobe, protopod overlapping with exopod; pereopod 1 propus without processes; pleopod 3 with transverse or oblique suture; uropods very short, under half as long as telson OR telson smaller than pereonite 7; TX+MO stygobites → Lirceolus (dubiously seperated from Caecidotea[/i])
4b. ♂ pleopod 2 exopod with or without plumose setae, with catch lobe, protopod not overlapping with exopod; pereopod 1 propus with or without processes; pleopod 3 with transverse suture; uropods usually longer, averaging around 0.5x-2x as long as telson (shorter in a few species), telson generally larger than pereonite 7; epigean, stygobitic or phreatobitic → Caecidotea (in part)
5a. Eyed epigean species, usually heavily pigmented → 6
5b. Eyeless, generally with little to no pigment → 7
6a. ♂️ pleopod 2 endopod with large basal spur; ♂️ pereopod 1 palm process without processes; Alaska and San Fransisco → Asellus
6b. ♂️ pleopod 2 endopod with a small basal process or lacking basal process; ♂️ pereopod 1 palm process with or without processes; widespread → Caecidotea
7a. Head with a small rostrum; ♂️ pleopod 2 endopod basal spur absent; WA, MT and Alberta → Salmasellus
7b. Head lacking rostrum; ♂️ pleopod 2 endopod basal spur present (small and inconspicuous in Bowmanasellus); Pacific coast states → 8
8a. Mandible with only a stub of a palp; ♂️ pleopod 1 protopod with only 1 linking hook; endemic to Malheur Cave in SW OR → Oregonasellus elliotti (monospecfic genus)
8b. Mandible with a 3-segmented palp; ♂️ pleopod 1 protopod with more than 1 linking hook, usually 2-3; not in Malheur Cave → 9
9a. ♂️ pleopod 2 endopod with odd bumpy globose structure (“lateral process”) posterior to tip, medial process forming a distal spine; Sequoia and Kings Canyon NP in CA → Bowmanasellus sequoiae (monospecific genus)
9b. ♂️ pleopod 2 endopod lacking odd bumpy globose structure posterior to tip, cannula forming a distal spine (when present); PNW to central-southern California → 11
10a. ♂️ pleopod 2 endopod basal spur mostly obscured dorsally, cannula alone at tip; hyporheic PNW → Columbasellus acheron (monospecific genus)
10b. ♂️ pleopod 2 endopod basal spur plainly visible doe sally, cannula backed by a very long broad round-tipped caudal process; general phrearobitic C CA → Calasellus
Habitat
Surface water species are restricted to 3 genera in North America (Caecidotea, Lirceus and Asellus)
Subterranean members of Caecidotea and Lirceus are also known, along with 7 small narrow-ranged subterranean-only genera (Lirceolus, Bowmanasellus, Calasellus, Columbasellus, Oregonasellus, Remasellus and Salmasellus)
Remarks
Across most of the continent there are only 1-2 genera in a given location, although in southern and western regions a few other genera are also known.
Caecidotea: +80 species found across the continent from west-central BC to Nova Scotia to the Everglades, probably absent from the southwest
Lirceus: +15 species endemic to the eastern US (S Quebec to E OK to N FL)
Asellus: only 2 species are known from North America: Asellus alaskensis from far northeastern Alaska and Asellus hilgendorfii introduced to central California. More are known from Eurasia
Remasellus: one species (R. parvus) endemic to N FL
Lirceolus: about 5-7 species mostly found in Texas (one in MO depending if it's placed here or in Caecidotea, while another reaches Coahuila), may just be a grade of abberant species in Caecidotea
Salmasellus: 2 species in the northwest in WA, Alberta and MT
Columbasellus: one species known from along the Columbia River in WA, probably more widespread
Oregonasellus: one species endemic to Malheur Cave, OR
Calasellus: at least 3 species (1 undescribed) in central CA
Bowmanasellus: one species endemic to Sequoia National Park in CA
