Microcerberus caroliniensis Wägele, Voelz & McArthur, 1995

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Suggested Common Name: Carolina Cerberus
Etymology: after South Carolina, where the only known localities of this species occur.
Taxonomic History: Microcerberus caroliniensis Wägele, Voelz & McArthur, 1995
Size Range: 1.5-2mm
Description: (modified from Wägele, Voelz & McArthur, 1995) Body nearly 10x longer than wide, pigmentless. Antenna 1 peduncle 3-segmented, segment 1 subsimilar to segment 3 with large plumose seta, segment 2 lacking setae; flagellum 3-segmented, segment 3 with with 1 plumose, 1 short simple and 1 long simple setae along with a long aesthetasc. Antenna 2 peduncle 6-segmented, segment 3 broad, laterally with 2 setae, with medial tooth; flagellum 7-segmented, segment 7 with 4 distal setae and a sensillum (resembling an aesthetasc). Mandible incisor 4-toothed; lacinia narrower on right; spine row with 3 (left) or 2 (right) serrated spines; molar slender, pointed; palp segment fused to mandible body. Labium U-shaped, each lateral lobe with 3 short sensilla. Maxilla 1 exopod lateral endite with 8 medially directed serrated spines, 2 proximally separated from others, medial endite short with 3 apical setae. Maxilla 2 rami with single strong spine. Maxilliped basis shorter than palp segment 3, lobe surpassing palp segment 1; palp segment 5 2-clawed. Pereonites 1-4 sternites strongly chitinized. Pereopod 1 inserted dorsolaterally; dactyl with 2 ventrodistal setae and 2 ventrodistal stout spines; claw elongate; propus palm with 5 serrate spines and 1 distal spine. Pereopods 2-4 inserted dorsally; dactyl short, rectangular, 2-clawed, dorsal claw slender; propus and carpus long-cylindrical; propus palm with proximal cuticular scales and distal spinelike and longer setae; merus short; basis with 2 long plumose dorsal setae; coxae visible dorsally. Pereonites 5-7 tergites thin, sclerites sometimes formed by dorsal cuticle supporting lateral border of tergites and area at base of pereopods. Pereopods 5-7 inserted dorsally, subsimilar to pereopods 2-4; propus palm with proximal spinelike seta; carpus with prominent plumose dorsal seta; coxae not visible dorsally. Pleonites 1-2 tergites present, long. ♂ pleopod 2 exopod ovate, seta lateral; endopod conical, long-pointed, tip curved laterally, lateral margin with cuticular comblike scales. Pleopod 3 uniramous, with 1 seta, covering base of pleopod 4. Pleopod 4 visible dorsally (moreso in ♂’s); protopod elongate, corrugated, longer in ♂’s, triramous. Pleopod 5 absent, replaced by 1-2 setae. Telson 1.5x longer than pleonites, nearly as long as pereonite 7, narrowing abruptly distally to truncate tip. Uropod protopod with 3 simple setae; exopod absent; endopod long-cylindrical with 4 plumose distal/subdistal setae.
Geographic Range: Currently only known from 2 nearby localities on Meyers Branch Creek in South Carolina near the SC/GA border. Found in wells about 1.2-2.4m deep about 7.4-31.9m from the creek.
Notes: This species can be distinguished from all other Microcerberids in the region (besides the undescribed species) by the elongate triramous pleopod 4. It appears to be closest to M. plesai (a Balkan species!) among known species in the genus, but can be differentiated from that species by the lack of a uropod exopod.

Sources

Coineau, N., & Elaine, F. (2001). Palaeobiogeography of the Freshwater Isopods Microcerberidae (Crustacea) from Caribbean and North America. In 13th International Congress of Speleology, 4th Speleological Congress of Latin América and Caribbean, 26th Brazilian Congress of Speleology. Brasilia, Brazil, July, 15-22.

Wägele, J. W., Voelz, N. J., & Vaun McArthur, J. (1995). Older than the Atlantic Ocean: discovery of a fresh water Microcerberus (Isopoda) in North America and erection of Coxicerberus, new genus. Journal of Crustacean Biology, 15(4):733-745.

Published: Feb 15, 2023