Triacanthoneus Anker, 2010

Anker, Arthur, 2020, Taxonomic remarks on the alpheid shrimp genus Triacanthoneus Anker, 2010 with description of a second eastern Pacific species (Malacostraca: Decapoda), Zootaxa 4772 (3), pp. 450-468 : 466-467

Key to the presently known species assigned to Triacanthoneus Anker, 2010

1A. Carapace with strong sharp dorsolateral teeth in hepatic or post-hepatic position; orbital teeth absent or present as broadly triangular lobes........................................................................................ 2

1B. Carapace without strong sharp dorsolateral teeth in hepatic or post-hepatic position; orbital teeth present, acute, arising from or near post-orbital margin................................................................................ 3

2A. Carapace with strong rostral + dorsal carina; eyestalk without anteromesial tubercle; cutting edges of major chela fingers with more than 20 minute teeth; third and fourth pereiopods with ischia unarmed [deep under coral rubble and in marine caves; depth range: 8–15 m; Belize and Cuba]............................................................. T. chapelianus

2B. Carapace without rostral + dorsal carina; eyestalk with subtriangular anteromesial tubercle; cutting edges of major chela fingers with less than 10 shallow, bump-like teeth; third and fourth pereiopods with ischia armed with stout cuspidate setae [under coral rubble, in burrows among mangrove roots]; depth range: 0.5–2 m; Caribbean coast of Panama]..... T. armatus comb. nov.

3A. Major chela with fingers much shorter than palm; antennular stylocerite with dorsal carina ending in acute or subacute tooth distally [East Pacific].................................................................................. 4

3B. Major chela with fingers as long as to much longer than palm; antennular stylocerite with dorsal carina, if present, unarmed distally [West Atlantic]................................................................................ 5

4A. Carapace with one robust seta in front of mid-dorsal tooth; rostrum horizontal or slightly descending, not ascending; telson narrow, about 3.3 times as long as maximal (proximal) width; minor cheliped carpus about 3.5 times as long as distal width [under large rocks on muddy sand; depth range: 0–2 m; Panama and Colombia]................................ T. pacificus

4B. Carapace with three robust setae in front of mid-dorsal tooth; rostrum ascending; telson moderately broad, about 2.6 times as long as maximal (proximal) width; minor cheliped carpus about 4.5 times as long as distal width [under large rocks on coarse sand; depth: 8–10 m; Panama]............................................................. T. blanca sp. nov.

5A. Rostrum with ventral tooth situated at rostral mid-length; major chela fingers extremely elongate, much longer than palm, distally strongly crossing, cutting edges with very conspicuous slender raptorial teeth intercalated between smaller teeth; pleural region with acute process above coxa of fifth pereiopod; epiopod of second maxilliped with podobranch; large-sized species (cl 8.0– 9.1 mm) [anchialine caves; Mexico]....................................................... T. akumalensis

5B. Rostrum with ventral tooth in subdistal position; major chela fingers subequal to palm to slightly longer, moderately elongate, distally not strongly crossing, cutting edges evenly serrated with small teeth, without raptorial teeth; pleural region without acute process above coxa of fifth pereiopod; epipod of second maxilliped without podobranch; small-sized species (cl under 4.5 mm) [coral reefs and adjacent rubble flats, sometimes close to mangroves; depth range: 0.5–15 m; Caribbean Sea].... 6

6A. Dorsal surface of telson with two pairs of small cuspidate setae, both pairs situated in posterior third of telson; eyestalk with cornea not particularly reduced, anteromesial surface with very small blunt tubercle; major and minor cheliped ischia with two spiniform setae; orbital teeth present in form of low bumps or subtriangular lobes [coral reefs and adjacent rubble flats; depth range: 0.5–15 m; southern Gulf of Mexico and Cuba]............................................... T. alacranes

6B. Dorsal surface of telson with two pairs (rarely with three pairs) of fairly large and robust cuspidate setae, first pair situated at mid-length of telson; eyestalk with cornea somewhat reduced, anteromesial surface with conspicuous conical tubercle; major and minor cheliped ischia with three spiniform setae; orbital teeth absent [sand flats with abundant coral rubble close to sea grass and mangroves; depth range: 0.5–2 m; Panama, possibly also southern Gulf of Mexico, as T. cf. toro , see above]..................................................................................................... T. toro