taxonID	type	description	language	source
039F5848FF99FFE0E5F3FA5AFC42CBF7.taxon	diagnosis	Diagnosis. Carapace with three strong, sharp, anteriorly directed teeth, one mediodorsal tooth situated posterior to carapace mid-length, and two teeth situated in post-hepatic position, anterior to mediodorsal tooth; frontal margin of carapace with or without orbital teeth, with well-developed rostrum, latter distally acute, with ventral margin bearing subterminal tooth; pterygostomial angle not produced anteriorly; cardiac notch deep. Eyes partly or largely visible in dorsal and lateral views. First to fourth abdominal somites rounded posteroventrally; fifth somite angular or slightly projecting posteroventrally; sixth somite without articulated plate. Telson slender, with two pairs of spiniform setae on dorsal surface; posterior margin straight, with two pairs of spiniform setae; anal tubercles absent. Antennular peduncle with strong mesioventral tooth on first segment; stylocerite reaching beyond distal margin of first segment, acute distally; lateral flagellum with well-developed accessory ramus. Antenna with scaphocerite ovate, with broad blade reaching beyond distolateral tooth; carpocerite short, not reaching half-length of scaphocerite. Mouthparts typical for family; mandible with bisegmented palp; maxillular palp with both lobes furnished with setae. Third maxilliped with lateral plate rounded or subacutely produced; ultimate segment tapering into corneous tip, without robust spiniform setae. Chelipeds strongly unequal and asymmetrical, carried folded; major cheliped elongate, slender; ischium with at least two spiniform setae; merus flattened ventrally; carpus subcylindrical, widening distally; chela smooth, finger cutting edges serrated; minor cheliped not elongate; ischium with at least two stout spiniform setae; chela simple, finger cutting edges straight. Second pereiopod with ischium bearing spiniform seta (e); carpus five-segmented, first segment longest. Third and fourth pereiopods very slender, with flexible ischio-meral articulation; ischium with spiniform setae; merus and carpus unarmed; propodus with small slender spiniform setae; dactylus simple, conical, relatively slender. Fifth pereiopod with propodal brush well developed or reduced. Second pleopod with appendix masculina and appendix interna, including ovigerous individuals. Uropod with slender exopod and endopod; diaeresis more or less sinuous. Gill / exopod formula: 5 pleurobranchs (above P 1 – 5); 1 arthrobranch (at Mxp 3); 0 podobranch; 2 lobe-shaped epipods (Mxp 1 – 2); 5 mastigobranchs (Mxp 3, P 1 – 4), 5 sets of setobranch (P 1 – 5); 3 exopods (Mxp 1 – 3).	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF99FFE0E5F3FA5AFC42CBF7.taxon	materials_examined	Type species. Triacanthoneus toro n. sp. Other species included. Triacanthoneus pacificus n. sp., T. alacranes n. sp.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF99FFE0E5F3FA5AFC42CBF7.taxon	etymology	Etymology. Name derived from the Latin adjective triacanthus (= with three spines) and the second part (- oneus) of Salmoneus, a closely related genus. Gender masculine.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF99FFE0E5F3FA5AFC42CBF7.taxon	distribution	Distribution. Transisthmian: tropical Western Atlantic (Panama, Gulf of Mexico) and tropical Eastern Pacific (Panama, Colombia). Phylogenetic position. Triacanthoneus n. gen. shares numerous features with Salmoneus, including the presence of a well-developed rostrum; absence of an articulated flap on the sixth abdominal somite; a complete gill-exopod formula; unequal and asymmetrical chelipeds, with the major cheliped carried folded; serrated cutting edges of the major chela fingers; and the presence of an appendix masculina in ovigerous individuals. More specifically, Triacanthoneus n. gen. has similarities with some species of the S. gracilipes Miya, 1972 group, especially S. armatus, which also has a small mediodorsal tooth on the carapace, apically bifid rostrum, partly exposed eyestalks, and the cheliped ischia armed with two stout spiniform setae (Anker 2010). However, in S. armatus, the small mediodorsal tooth is distinctly more anterior compared to the much stronger mediodorsal tooth of Triacanthoneus n. gen., and therefore, these two teeth do not appear to be homologous. In addition, all three species of Triacanthoneus n. gen. possess a strong post-hepatic tooth on each side and anterior to the mediodorsal tooth. The ischio-meral articulation of Triacanthoneus n. gen. appears to be flexible (see Figs. 4 G, I, 9 G, I), which is not the case in Salmoneus (see figures in Anker 2003 a, 2003 b; Anker & Marin 2006; Anker 2010). The presence of three sharp teeth on the carapace and a facilitated ischio-meral articulation at once separate Triacanthoneus n. gen. from Salmoneus and all other alpheid genera. It remains clear that a taxonomic revision of Salmoneus sensu lato, combined with a molecular analysis, is becoming more and more necessary; some of the species groups (e. g. S. jarli Holthuis, 1951 and S. gracilipes groups) may indeed need to be elevated to generic rank. Other remarks. Curiously, all known specimens of Triacanthoneus n. gen., seven in total, are both ovigerous and have a well-developed appendix masculina, reminiscent of the situation in Salmoneus (Carvacho 1989; Anker 2010) and suggesting some form of hermaphroditism. Furthermore, all three species of the new genus are characterised by the relatively small number (usually no more than 20, cf. Figs. 1, 7) large eggs or embryos, indicating advanced larval development.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9AFFE5E5F3F955FECDCD29.taxon	materials_examined	Type material. Holotype: ovigerous female (CL 4.1 mm), USNM 1145375, Panama, Caribbean coast, Bocas del Toro, Isla Colón, Punta Caracol, subtidal sand flat with rubble and sparse seagrass, near mangroves, depth 1.5 m, under rubble in sand, coll. A. Anker, 1 April 2008, fcn 08 - 022. Paratypes: 1 ovigerous female (CL 3.4 mm), USNM 1145376, Panama, Caribbean coast, Bocas del Toro, Isla Colón, Punta Caracol, subtidal sand flat with rubble and sparse seagrass, near mangroves, depth 1.5 m, under rubble in sand, coll. A. Anker, J. A. Baeza, I. Marin, 28 April 2007, fcn 07 - 156 (dissected); 1 ovigerous female (CL 3.4 mm), OUMNH. ZC 2010 - 01 - 005, same collection data as for previous specimen, fcn 07 - 157; 1 ovigerous female (CL 2.5 mm), UP, Bocas del Toro, east of Isla San Cristobal, Laguna Porras, Sta. 9, 9 º 16 ’ 514 ” N, 82 º 14 ’ 833 ” W, depth 7 m, loose coral rubble, coll. S. De Grave & M. Salazar, 2 August 2005, fcn 08 - 254.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9AFFE5E5F3F955FECDCD29.taxon	description	Description. Small-sized alpheid shrimp. Carapace with one strong sharp mediodorsal tooth situated slightly posterior to carapace mid-length and two strong sharp dorsolateral teeth situated ventral and anterior to mediodorsal tooth, in post-hepatic area (Figs. 1, 2 B, D). Rostrum straight, more than 1.5 times as long as broad at base; lateral margins slightly concave; tip overreaching distal margin of first segment of antennular peduncle; ventral margin with distinct, anteriorly directed subapical dent; rostral carina well developed, reaching posteriorly to mediodorsal tooth; orbital teeth absent (Fig. 2 A – C). Pterygostomial angle not protruding anteriorly, broadly rounded (Fig. 2 B). Pleura of first to fourth abdominal somites rounded posteroventrally; fifth pleuron with posteroventral angle produced in small tooth (Fig. 1). Telson narrow, at least 3.5 times as long as wide in proximal third, tapering distally; dorsal surface with two pairs of strong spiniform setae situated at some distance from lateral margins, at about 0.5 and 0.8 telson length, respectively; posterior margin straight, each posterolateral angle with two pairs of spiniform setae, mesial being 0.6 times as long as lateral, and two plumose setae between mesial spiniform setae (Fig. 2 L, M). Eyes partly exposed in dorsal and lateral views; cornea somewhat reduced, well pigmented, occupying anterolateral portion of eyestalk, anteromesial margin with small blunt process (Fig. 2 A, B). Antennular peduncle stout, with second segment distinctly longer than wide; first segment with distally acute stylocerite reaching to about 0.4 length of second segment; ventromesial carina of first segment with anteriorly directed tooth; lateral flagellum biramous, fused portion composed of at least three segments; accessory ramus composed of four or so partly fused segments with groups of aesthetascs (Fig. 2 A, B, F). Antenna with stout basicerite bearing sharp distoventral tooth; scaphocerite reaching to end of antennular peduncle, ovate; blade broad, with anterior margin convex, reaching slightly beyond strong distolateral tooth; carpocerite barely reaching 0.5 length of scaphocerite (Fig. 2 A, B, G). Mouthparts typical for genus, as illustrated (Fig. 3 A – F). Third maxilliped with coxa bearing rounded lateral plate above mastigobranch; antepenultimate segment elongate, flattened; penultimate segment elongate, slender; ultimate segment tapering distally, ending in corneous tip, without robust setiform setae on apex; arthrobranch well developed (Fig 3 G). Chelipeds very unequal in size and asymmetrical in shape, carried folded (Fig. 4 A, D). Major cheliped enlarged, elongate, slender; ischium rather long, slender, ventrolateral surface with three stout spiniform setae; merus much longer than ischium, slender, smooth, ventrally flattened; carpus distinctly shorter than merus, subcylindrical, distally somewhat broadening, smooth; chela subcylindrical, smooth; fingers longer than palm, compressed, slightly twisted, cutting edges evenly serrated, with at least 18 subtriangular teeth (Fig. 4 A – C). Minor cheliped not particularly enlarged, slender; ischium long, ventrolateral surface with three stout spiniform setae; merus slightly longer than ischium, somewhat compressed, smooth; carpus slightly shorter than merus, subcylindrical, slightly widening distally, smooth; chela simple, smooth, with fingers slightly longer than palm, finger cutting edges straight, except for a few small distal teeth (Fig. 4 D, E). Second pereiopod slender; ischium about as long as merus, with three spiniform setae on ventrolateral surface; carpus five-segmented, first segment longest, slightly longer than sum of four other segments, ratio of carpal segments (from proximal to distal) more or less equal to: 5.5: 1: 1: 1.5: 1.5; chela simple, longer than most-distal carpal article (Fig. 4 F). Third pereiopod very slender, compressed; ischium elongate, with two spaced spiniform setae on ventrolateral surface; merus elongate, almost 10 times as long as wide, smooth; carpus longer than merus, with slender stiff distoventral seta; propodus with one slender spiniform seta on ventral margin and one stouter distal spiniform seta adjacent to dactylus; dactylus almost 0.5 propodus length, simple, conical, very slender, gradually curving distally, furnished with setae on dorsal margin (Fig. 4 G, H). Fourth pereiopod almost identical to third pereiopod. Fifth pereiopod longer and more slender than third or fourth pereiopods; ischium unarmed; carpus distinctly longer than merus, propodus with two small spiniform setae on ventral margin and at least six rows of slender serrulate setae on distolateral surface, most-distal row with longest setae reaching well beyond dactylar base (Fig. 4 I). Second pleopod of all four (ovigerous) specimens with appendix interna and appendix masculina, latter shorter than appendix interna, with stiff apical and subapical setae (Fig. 2 I). Uropod with lateral lobe of protopod ending in small subacute tooth; exopod and endopod slender; exopod with sinuous diaeresis and blunt distolateral tooth adjacent to robust spiniform seta (Fig. 2 J, K). Gill-exopod formula as described for genus (see above). Colour in life semitransparent-white, gonads yellow (Fig. 10 A – C).	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9AFFE5E5F3F955FECDCD29.taxon	etymology	Etymology. Specific name derived from the third word of the type locality, Bocas del Toro; toro also means bull in Spanish, alluding to the two horn-like projections on the carapace; used as a noun in opposition. Habitat. Sand flats with abundant rubble and seagrass, at some distance from fringing mangroves, at depth range of 1.5 – 7 m; most specimens were found on sand deep under large pieces of rubble, one was found among loose rubble.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9AFFE5E5F3F955FECDCD29.taxon	materials_examined	Type locality. Bocas del Toro, Caribbean coast of Panama.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9AFFE5E5F3F955FECDCD29.taxon	distribution	Distribution. Presently known only from the type locality on the Caribbean coast of Panama.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9AFFE5E5F3F955FECDCD29.taxon	discussion	Remarks. One of the paratypes has a somewhat aberrant rostrum, with two instead of one subapical dent (Fig. 2 N).	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9FFFEAE5F3FC5AFF36C989.taxon	materials_examined	Type material. Holotype: ovigerous female (CL 2.8 mm), USNM 1145374, Panama, Pacific coast, Playa Venao, intertidal, exposed at low tide, under rocks in sand, coll. J. A. Baeza (processed by A. Anker), 18 March 2007, fcn 07 - 090. Additional material examined. 2 ovigerous females (CL 2.9, 3.4 mm), UVC, Colombia, Pacific coast, Bahía Malaga, Los Negros, sand-rock bottom, depth 2 m, ARMS (large plastic basket with shells), 25 April 2009, coll. J. F. Lazarus-Agudelo et al. (processed by A. Anker), fcn COL- 00135, COL- 00136.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9FFFEAE5F3FC5AFF36C989.taxon	description	Description. Small-sized alpheid shrimp. Carapace with one strong sharp mediodorsal tooth situated distinctly posterior to carapace mid-length and two strong sharp dorsolateral teeth situated ventral and anterior to mediodorsal tooth, in post-hepatic area; stiff seta present on mid-dorsal line anterior to mediodorsal tooth (Fig. 5 B, C). Rostrum straight, more than 1.7 times as long as broad at base; lateral margins slightly concave; tip overreaching mid-length of second segment of antennular peduncle; ventral margin with strong, anteroventrally directed subapical dent; rostral carina well developed, reaching posteriorly to mediodorsal tooth, with one stiff seta approximately at carapace mid-length; orbital teeth obscure, present as small bumps lateral to eye (Fig. 5 A – E). Pterygostomial angle not protruding anteriorly, broadly rounded (Fig. 5 B). Pleura of first to fourth abdominal somites rounded posteroventrally; fifth pleuron with posteroventral angle subacute. Telson narrow, almost four times as long as wide in proximal third, tapering distally; dorsal surface with two pairs of strong spiniform setae situated at some distance from lateral margins, at about 0.5 and 0.75 telson length, respectively; posterior margin straight, each posterolateral angle with two pairs of spiniform setae, lateral being 0.7 times as long as mesial, and two long plumose setae between mesial spiniform setae (Fig. 5 J). Eyes partly exposed in dorsal and lateral views; cornea somewhat reduced, well pigmented, occupying anterolateral portion of eyestalk, anteromesial margin with small blunt process (Fig. 5 A, B). Antennular peduncle stout, with second segment distinctly longer than wide; first segment with distally acute stylocerite reaching to 0.4 – 0.5 length of second segment; ventromesial carina of first segment with anteriorly directed tooth; lateral flagellum biramous, fused portion composed of at least three segments; accessory ramus composed of four or so partly fused segments with groups of aesthetascs (Fig. 5 A, B). Antenna with stout basicerite bearing sharp distoventral tooth; scaphocerite reaching or almost reaching to end of antennular peduncle, ovate; blade broad, with anterior margin convex, reaching slightly beyond strong distolateral tooth; carpocerite barely reaching 0.5 length of scaphocerite (Fig. 5 A, B). Mouthparts not dissected, appearing typical for genus in external view. Third maxilliped with coxa bearing rounded lateral plate above mastigobranch; antepenultimate segment elongate, flattened; penultimate segment elongate, slender; ultimate segment tapering distally, ending in corneous tip, without robust setiform setae on apex; arthrobranch well developed (Fig 5 F). Chelipeds very unequal in size and asymmetrical in shape, carried folded (Fig. 6 A, D). Major cheliped enlarged, elongate, slender; ischium rather long, slender, ventrolateral surface with three stout spiniform setae; merus much longer than ischium, slender, smooth, ventrally flattened; carpus much shorter than merus, subcylindrical, distally broadening, smooth; chela subcylindrical, smooth; fingers shorter than palm, compressed, cutting edges evenly serrated, with around 10 subtriangular teeth (Fig. 6 A – C). Minor cheliped not particularly enlarged, slender; ischium long, ventrolateral surface with three stout spiniform setae; merus slightly longer than ischium, somewhat compressed, smooth; carpus shorter than merus, subcylindrical, slightly widening distally, smooth; chela simple, smooth, with fingers longer than palm, finger cutting edges straight (Fig. 6 D, E). Second pereiopod slender; ischium as long as merus, with three spiniform setae on ventrolateral surface; carpus five-segmented, first segment longest, as long as sum of four other segments, ratio of carpal segments (from proximal to distal) more or less equal to: 6: 1.5: 1: 1.5: 2; chela simple, longer than most-distal carpal article (Fig. 6 F, G). Third pereiopod very slender, compressed; ischium elongate, with two spaced spiniform setae on ventrolateral surface; merus elongate, about 10 times as long as wide, smooth; carpus as long as merus; propodus with two slender spiniform setae on ventral margin and one stouter and longer distal spiniform seta adjacent to dactylus; dactylus about 0.45 propodus length, simple, conical, very slender, gradually curving distally, furnished with setae on dorsal margin (Fig. 6 H, I). Fourth pereiopod almost identical to third pereiopod. Fifth pereiopod longer and more slender than third or fourth pereiopods; ischium unarmed; carpus slightly longer than merus, propodus with one small spiniform seta on ventral margin and at least five rows of slender serrulate setae on distolateral surface, most-distal row with longest setae reaching well beyond dactylar base (Fig. 6 J, K). Second pleopod (of both ovigerous specimens) with appendix interna and appendix masculina, latter exceeding than appendix interna, with stiff apical and subapical setae (Fig. 5 G). Uropod with lateral lobe of protopod ending in small subacute tooth; exopod and endopod slender; exopod with sinuous diaeresis and blunt distolateral tooth adjacent to robust spiniform seta (Fig. 5 H, I). Gill-exopod formula as described for genus (see above). Colour in life semitransparent-white, sometimes with pale orange tinge; gonads or eggs yellow-orange (Fig. 10 D – F).	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9FFFEAE5F3FC5AFF36C989.taxon	etymology	Etymology. Name refers to the Pacific Ocean; the two other species of the new genus are confined to the Atlantic Ocean. Habitat. The Panamanian type specimen was collected in the mixed sand-mud-rock intertidal at low tide, on sand under large rocks; the Colombian specimen was extracted from an improvised ARMS (large basket with shells) placed on a rock-sand bottom at about 2 m.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9FFFEAE5F3FC5AFF36C989.taxon	materials_examined	Type locality. Playa Venao, Pacific coast of Panama.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9FFFEAE5F3FC5AFF36C989.taxon	distribution	Distribution. Presently known only from Playa Venao, Panama, and Bahía Malaga, Colombia, in the tropical Eastern Pacific.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF9FFFEAE5F3FC5AFF36C989.taxon	discussion	Remarks. Triacanthoneus pacificus n. sp. differs from T. toro n. sp. and T. alacranes n. sp. by the distinctly more robust major chela; and the more ventrally directed subapical dent on the ventral margin of the rostrum; specifically from T. toro n. sp. by the more posterior position of the mediodorsal tooth on the carapace. It specifically differs from T. alacranes n. sp. by the absence of orbital teeth, the more anterior position of the dorsolateral teeth of the carapace, and several other features (see under T. alacranes n. sp. below).	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF92FFEDE5F3F923FC2BCC92.taxon	materials_examined	Type material. Holotype: ovigerous female (CL 3.7 mm), UNAM-CNCR 26177, Mexico, Yucatán, Arrecife Alacranes (Alacranes Reef), sta ALN 39, La Anegada, 22 ° 27 ' 37.2 '' N, 89 ° 36 ' 40.6 '' W, shallow flat with sand and abundant rocks and coral rubble, near channel, depth 0.5 m, in crevices under rocks, coll. N. Simões and J. Duarte-Gutiérrez, 11 August 2009, fcn JD- 061 B.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF92FFEDE5F3F923FC2BCC92.taxon	description	Description. Small-sized alpheid shrimp. Carapace with one strong sharp mediodorsal tooth situated in posterior third of carapace and two strong sharp dorsolateral teeth situated slightly ventral and slightly anterior to mediodorsal tooth, and slightly posterior to mid-length of carapace, significantly posterior to hepatic area (Figs. 7, 8 B – E). Rostrum straight, more than 1.5 times as long as broad at base; lateral margins slightly concave; tip overreaching distal margin of first segment of antennular peduncle; ventral margin with small, anteriorly directed subapical dent; rostral carina strong, reaching posteriorly to mediodorsal tooth; orbital teeth present, small, sharp, lateral to eye (Fig. 8 A – C). Pterygostomial angle not protruding anteriorly, broadly rounded (Fig. 8 B). Pleura of first to fourth abdominal somites rounded posteroventrally; fifth pleuron with posteroventral angle subacute (Fig. 7). Telson relatively narrow, at least 3.2 times as long as wide in proximal third, tapering distally; dorsal surface with two pairs of small submarginal spiniform setae situated both in posterior half of telson, at about 0.7 and 0.8 telson length, respectively; posterior margin straight, each posterolateral angle with two pairs of spiniform setae, lateral being 0.8 times as long as mesial, and six plumose setae between mesial spiniform setae (Fig. 8 L, M). Eyes partly exposed in dorsal and lateral views; cornea not particularly reduced, well pigmented, occupying entire anterior portion of eyestalk, anteromesial margin without process (Fig. 8 A, B). Antennular peduncle stout, with second segment approximately as long as wide; first segment with distally acute stylocerite reaching to 0.7 length of second segment; ventromesial carina of first segment with anteriorly directed tooth; lateral flagellum biramous, fused portion composed of at least three segments; accessory ramus composed of three or so partly fused segments with groups of aesthetascs (Fig. 8 A, B). Antenna with stout basicerite bearing sharp distoventral tooth; scaphocerite not reaching to end of antennular peduncle, ovate; blade broad, with anterior margin convex, not reaching beyond strong distolateral tooth; carpocerite not reaching beyond 0.5 length of scaphocerite (Fig. 8 A, B). Mouthparts not dissected, appearing typical for genus in external view. Third maxilliped with coxa bearing dorsally slightly produced lateral plate above mastigobranch; antepenultimate segment elongate, flattened; penultimate segment elongate, slender; ultimate segment tapering distally, ending in corneous tip, with small setiform seta on apex; arthrobranch moderately developed (Fig. 8 G, H). Chelipeds very unequal in size and asymmetrical in shape, carried folded (Fig. 9 A, D). Major cheliped enlarged, elongate, slender; ischium moderately elongate, slender, ventrolateral surface with two stout spiniform setae; merus almost twice as long as ischium, slender, smooth, ventrally flattened; carpus distinctly shorter than merus, vase-shaped, distally broadening, smooth; chela subcylindrical, smooth; fingers about same length as palm, compressed, slightly twisted, cutting edges evenly serrated, with at least 12 subtriangular teeth (Fig. 9 A – C). Minor cheliped not particularly enlarged, slender; ischium long, with two stout spiniform setae on ventrolateral surface; merus longer than ischium, somewhat compressed, smooth; carpus about 0.6 length of merus, subcylindrical, slightly widening distally, smooth; chela simple, smooth, with fingers slightly shorter than palm, finger cutting edges straight, except for a few small teeth in distal half (Fig. 9 D, E). Second pereiopod slender; ischium about as long as merus, with one spiniform seta on ventrolateral surface; carpus five-segmented, first segment longest, longer than sum of four other segments, ratio of carpal segments (from proximal to distal) more or less equal to: 6: 1: 1: 1.5: 1.8; chela simple, longer than mostdistal carpal article (Fig. 9 F). Third pereiopod slender, compressed; ischium elongate, with two spaced spiniform setae on ventrolateral surface; merus elongate, at least nine times as long as wide, smooth; carpus slightly shorther than merus; propodus with two small spiniform setae on ventral margin and one larger distal spiniform seta adjacent to dactylus; dactylus slightly less than 0.4 propodus length, simple, conical, slender, gradually curving distally, furnished with setae on dorsal margin (Fig. 9 G, H). Fourth pereiopod nearly identical to third pereiopod. Fifth pereiopod longer and more slender than third or fourth pereiopods; ischium unarmed; carpus as long as merus, propodus apparently without spiniform setae on ventral margin, propodal bruish reduced to one distal row of serrulate setae at base of dactylus (Fig. 9 I, J). Second pleopod (of ovigerous specimen) with appendix interna and appendix masculina, latter much shorter than appendix interna, with stiff apical and subapical setae (Fig. 8 I). Uropod with lateral lobe of protopod ending in small blunt tooth; exopod and endopod slender; exopod with sinuous diaeresis and obscure, blunt distolateral tooth adjacent to slender spiniform seta (Fig. 8 J, K). Gill-exopod formula as described for genus (see above). Colour in life semitransparent-white, gonads yellow (Fig. 10 G).	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF92FFEDE5F3F923FC2BCC92.taxon	etymology	Etymology. Specific name derived from Alacranes Reef, the type locality of this new species; used as a noun in opposition. Habitat. Shallow flat with sand and rocks, near slope to a deeper channel; the single specimen was found under a rock at a depth of 0.5 m.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF92FFEDE5F3F923FC2BCC92.taxon	materials_examined	Type locality. Alacranes Reef, about 130 km north of Progreso, Yucatán Peninsula.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF92FFEDE5F3F923FC2BCC92.taxon	distribution	Distribution. Presently known only from the type locality in the southern Gulf of Mexico, off Yucatán.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
039F5848FF92FFEDE5F3F923FC2BCC92.taxon	discussion	Remarks. Triacanthoneus alacranes n. sp. differs from the other two species of the genus by the more posterior and also more dorsal position of the dorsolateral teeth on the carapace; the more posterior position of the mediodorsal tooth on the carapace; the more pronounced rostral carina; the presence of orbital teeth; the presence of only two spiniform setae on the ischium of the major and minor chelipeds (vs. three in the other two species); the reduced propodal brush on the fifth pereiopod; and the wider telson, with much smaller dorsal spiniform setae, all four situated in the posterior half of the telson.	en	Anker, Arthur (2010): A new genus and three new species of alpheid shrimps (Crustacea, Decapoda, Caridea) from the tropical American coasts. Zootaxa 2652: 47-63, DOI: 10.5281/zenodo.198863
