Alpheus luiszapatai, Ramos-Tafur, 2018

Ramos-Tafur, Gabriel E., 2018, Alpheus luiszapatai, a new species of rare and colorful deep water alpheid shrimp (Crustacea: Decapoda: Alpheidae) from Arusí, Chocó Department, Pacific Coast of Colombia, Zootaxa 4403 (3), pp. 540-556 : 542-551

Alpheus luiszapatai sp. nov.

( Figs. 2–5 )

Holotype. Female , CL 22.9 mm; TL 62.4 mm: NE of Arusí , Chocó Department, Pacific Coast of Colombia, 05°40’05’’N, 77°25’03’’W ( Fig. 1 ), “ Dituva ” (Russian commercial shrimp trawler working under contract with INPA – Buenaventura), bottom trawl N° 153, deep ~ 245 m (136 fathoms) 9:00 AM; water surface temperature 28°C; with Solenocera spp., and several fishes and invertebrates unidentified; 28 Jul 1992, coll. Wilson Niño (scientific observer onboard), USNM 1468999 .

Comparative material examined. Alpheus floridanus Kinsley, 1878 (sensu lato). West coast of Florida, Gulf of Mexico: 1 female, CL 6.3 mm, TL 19.8 mm; ~ 38 miles W of Egmont Key (27°37’00’’N, 83°28’00’’W), R/ V Hernan Cortez, sta C, Cruise HC29, net-trawl, depth 37 m, 18 Jul 1966, coll. Robert F. Presley, ( FSBCI 046889 ) .— 1 male CL 9.3 mm, TL 25.5mm; 1 ovigerous female, CL 8.8 mm TL 27.2 mm; ~ 24 miles W of Sanibel Island Light, Fort Myers (26°23’59’’N, 82°28’00’’W), R/ V Hernan Cortez, sta J, Cruise HC31, dredging, depth 18 m, 4 Sep 1966, coll. Robert F. Presley, ( FSBCI 046885 ) .— 2 males, CL 8.3, 9.4 mm, TL 27.2, 30.1 mm; ~ 38 miles W of Egmont Key (27°37’00’’N, 83°28’00’’W), R/ V Hernan Cortez, sta C, Cruise HC 35, net-trawl, depth 37 m, 25 Jan 1967, coll . Robert F. Presley , ( FSBCI 046887 ).— 1 male CL 7.8mm, TL 21.6 mm , 1 female CL 8.6 mm, TL 23.9 mm, ~ 38 miles W of Egmont Key , same coordinates as previous, R/V Hernan Cortez, sta C, Cruise HC45, nettrawl, depth 37 m, 2 Nov 1967, coll. Robert F. Presley, ( FSBCI 046888 ) .— Gulf of Mexico North: 1 male, CL 7.9 mm, TL 25.2 mm, Mississippi River Delta (29°04’36’’N, 88°59’13’’W), R/ V Oregon II, sta 282, Cruise 243, depth 32 m, 19 November 2000, coll . NOAA crew (FSBCI 080550).— E coast of Florida : 1 male, CL 7.7 mm, TL 22.6 mm, ~ 28 miles E of Cape Canaveral, (28°50’13N, 80°08’34’’W), R/ V Delaware II, sta 0 75, Cruise 83-05, dredging, depth 64 m, 23 Apr 1983, coll . William G. Lyons , David K. Camp, et al. ( FSBCI 046882 ).— 4 males CL 6.1 mm, 7.4 mm, 9.1 mm, 10.9 mm, TL 17.4 mm, 20.7 mm, 24.2 mm. 24.6 mm , 1 female, CL 8.0 mm, TL 23.3 mm, 2 ovigerous females CL 7.5 mm, 7.9 mm, TL 22.6 mm, 23.8 mm, ~ 51 miles E of Matanzas Inlet (29°40’03’’N, 80°16’ 25’’W), R/ V Delaware II, sta 109, Cruise 83-05, dredging, depth 64 m, 25 Apr 1983, coll .

William G. Lyons, David K. Camp, et al. (FSBCI 046883).— 1 male, CL 7.4 mm, TL 24.7mm, ~ 18 miles ENE of Sebastian Inlet (27°54’24’’N, 80°06’42’’W), R/ V Delaware II, sta 0 14, Cruise 84-05, dredging, depth 38 m, 18 May 1984, coll. William G. Lyons, David K. Camp, et al. ( FSBCI 046881 ) .— 1 male, CL 9.1 mm, TL 29.9 mm, ~ 28 miles ENE of Cape Canaveral (28°50’41’’N, 80°10’36’’W), R/ V Delaware II, sta 0 68, Cruise 84-05, dredging, depth 53 m, 21 May 1984, coll. William G. Lyons, David K. Camp, et al. ( FSBCI 046884 ) .

Alpheus aequus Kim & Abele, 1988: 1 male, CL 2.9 mm, 1 female, CL 4.3 mm, La Barra , Isla Gorgona, Pacific Colombia, 28 Sep 1988, coll. Rebeca Franke, (CRBMUV 88011). — 1 female, CL 4.4 mm, Estrecho de Tasca , Isla Gorgona, 18 Sep 1989, coll. Rebeca Franke, ( USNM 244252 ) .

Alpheus rostratus Kim & Abele, 1988: 1 male, CL 4.4 mm, 1 ovigerous female, CL 3.9 mm, Isla Gorgonilla , Isla Gorgona, Pacific Colombia, 10 Mar 1989, coll. Rebeca Franke, ( USNM 244247 ) .

Alpheus paracrinitus Miers, 1881: 1 male, CL 3.6 mm, La Barra, Isla Gorgona , Pacific Colombia, 1 Feb 1987, coll. Rebeca Franke, USNM 244254 .— 1 male CL 3.0 mm La Barra, Isla Gorgona , Pacific Colombia, 28 Sep 1988, coll. Rebeca Franke, (CRBMUV 88018). — 1 male, CL 3.2 mm, 1 female, CL 3.5 mm, Playa Pizarro , Isla Gorgona, Pacific Colombia, 12 Apr 1987, coll. Rebeca Franke, ( USNM 244259 ) .

Diagnosis. Large size alpheid shrimp, CL 22.9 mm, putatively placed in Alpheus brevirostris (Olivier, 1811) species group. Rostrum short, triangular, tip slightly directed downward, not reaching middle of visible part of first antennular segment. Ocular hoods rounded, unarmed. Scaphocerite with lateral tooth slightly overreaching lamella, shorter than carpocerite. Basicerite armed with strong acute lateral tooth. Eyes partially visible in frontal view, eyestalk furnished with two small triangular teeth. Ocellar beak present. Mandible with seven acute plus three rounded teeth on incisor process; molar process ending centrally in broad triangular tooth. First maxilliped with caridean lobe visibly inflated. Exopod of third maxilliped overreaching distal end of antepenultimate segment. Major cheliped and minor cheliped with merus crenulated in both inferior margins, furnished with small spines and long setae on each pit. Major chela subrectangular in lateral view, pear shape in cross section; without distodorsal transverse groove; lateral and mesial margins flanking fossa of pollex elevated, dorsally crenulated, with tufts of long setae on each pit. Minor chela with acute triangular tooth at each side of dactylar articulation. Third leg with ventral movable spine on ischium; merus without ventrodistal tooth or spines; propodus with 8–12 ventral movable spines; dactylus conical. Telson without longitudinal median depression. Exopodal uropod with sinusoidal diaresis.

Description of female holotype. Large-sized shrimp species, pertaining to Alpheus brevirostris (Olivier, 1811) species group ( Fig. 2 ). Carapace smooth, glabrous, compressed laterally, with conspicuous cardiac notch, and shallow grooves behind and under ocular hoods; pterygostomial region slightly angled, but not projected; ventral margin sinuous and broadly rounded.

Rostrum short, triangular, somewhat longer than wide at base ( Figs. 3 A–B ), with acute tip slightly curved and directed downward, slightly overreaching distal margin of ocular hoods and barely reaching to middle of visible part of first antennular segment; two elongated setae present in each side of rostral carina (one entire seta present, other three lost during manipulation of specimens but pits and basal parts of setae still visible), with distal end reaching little beyond of middle part of second antennular segment. Rostral base with ventral part roofed by small patch of short setae. Rostral carina linear dorsally, slightly reaching posterior end of eyes. Ocular hoods inflated dorsally, produced anteriorly, anterior margin smooth without acute teeth or spines, very convex distally and deeply concave near base of rostrum; adrostral furrows shallow, but clearly marked. Ocellar beak present, well developed, with broadly rounded tip, directed upward, clearly visible in fronto-lateral view ( Fig. 3C ). Eyes partially visible in frontal view, eyestalk ornamented with two conspicuous and acute triangular teeth, the smallest situated near of cornea, second one larger, close to ocellar beak.

Antennules slender. First antennular segment ventral margin with deep, broad subtriangular carina, ventral margin broadly rounded ( Fig. 3D ); distal margin sinuous. Second segment elongated, about 2.9 times as long as broad, and 1.3 times as long as visible part of first segment, and 2.7 times as long as third segment. Stylocerite broad anteriorly, tapering distally to form a sharp point, with tip not reaching distal margin of first antennular segment.

Scaphocerite rather narrow, with outer margin slightly concave at middle, about 3.5 times as long as broad; lateral tooth of left blade overreaching slightly end of third antennular segment, but shorter than distal end of carpocerite; lateral tooth of right blade missing. Inner blade or squamous portion shorter than lateral tooth. Carpocerite slender 5.0 times as long as broad, overreaching distal end of antennular peduncle by 0.7 length of third antennular segment. Basicerite with strong lateral acute tooth, dorsal margin unarmed ending distally as rounded knob.

Mouth parts ( Fig. 4 ), left side dissected. Mandible ( Fig. 4A ) with incisor process well developed, furnished with seven acute, plus three rounded teeth on distal margin; palp two segmented, furnished with abundant marginal setae; molar process robust, ending centrally as broad triangular tooth. First maxilla ( Fig 4B ) with elongated bilobed palp, inner lobe with large distal seta. Second maxilla ( Fig. 4C ) with scaphonagthite inflated and palp with tip bilobed. First maxilliped with globose caridean lobe and epipod bilobed, which is bigger than endites ( Fig. 4D ). Second maxilliped with upper part of epipod inflated and elongated exopod ( Fig. 4E ). Third maxilliped ( Fig. 4F ) overreaching distal part of basicerite by near 0.5 distal of ultimate segment, overall heavily setose; ultimate segment tapering distally, more than 1.2 times as long as penultimate segment; penultimate segment triangular in cross section, about 4.0 times as long as broad; antepenultimate segment triangular in cross section, about 1.5 times as long as penultimate segment. Exopod slightly overreaching distal end of antepenultimate segment. Precoxa without arthrobranch or pleurobranch, with strap like epipod.

First pair of pereopods dissimilar in shape and size. Left first pereopod or major cheliped ( Figs. 2 , 5A–B ) overreaching distal end of carpocerite by entire length of chela. Chela elongated and compressed laterally about 3.1 times as long as broad, with fingers occupying distal 0.25; palm ovoid in cross section. External palm smooth without notches, sculptures or big tubercles on dorsal or ventral margins, but with patches of small tubercles, granules and pits present proximally on ventral margin and several setae on dorsal and inferodistal margins. Longitudinal depression or external palmar groove shallow, irregular but well defined, starting near of linea impressa, extending distally to dactylar articulation; additional shallow slender depression or inferior palmar groove present below of last one, but of smaller size, extending from distal third of palm to below base of fixed finger. Proximal margin with deep and wide sinuous cicatrix, extending irregularly across of dorsal to ventral margins—this cut is a clear deep fracture of exoskeleton, which could had been caused by an older accident—. Linea impressa or oblique suture, transversal, well defined, cut short of proximal margin by cicatrix. Superodistal margin truncated, slightly upturned, furnished with patches of long setae. Mesial palm with ventral margin irregular, shaped by presence of small protuberances, pits and setae. Dorsal margin with well defined sinuous longitudinal depression or superior longitudinal groove, extending along entire margin and adorned with small irregular tubercles and long setae, ending distally as truncated projection, furnished with few long setae. Noticeable shallow irregular depression or internal palmar groove present, visible from middle of palm to dactylar articulation, ending distally in an area covered by stiff short setae and mesial triangular tooth. Conspicuous swollen area present at middle lower central part, which in dorsal or ventral view looks hump-shaped. Adhesive plate present in front of distosuperior truncate area, surrounded ventrally by abundant stiff short setae. Immovable finger with tip broadly truncate, ornate with tufts of long setae. Cutting edge with deep fossa, ovoid in dorsal view, flanked externally and mesially with blunt projections, external projection broadly rounded with dorsal margin furnished with 5 small pits, given appearance of crenulated margin or margin with rounded teeth, each furnished with tufts of 10 or more long setae; mesial blunt projection slightly angular, dorsal margin with 6 deep visible pits, each with tufts of elongated setae, some of them reaching dorsal margin of dactylus ( Fig. 5G ). Movable finger compressed laterally, with dorsal margin strongly arcuate, tip bluntly rounded, overreaching slightly tip of immovable finger; subdistal patches of long setae on mesial and external faces; adhesive plate present, ovoid, well developed; plunger of moderate development, with ventral margin flattened and with single sensilla seta present in middle of flat area or closing surface, but with more of one dozen plumose setae in proximal concavity before plunger ( Fig. 5H ).

Carpus cup shape with several distodorsal setae; inner inferior margin ending as distal triangular tooth; dorsal margin slightly flattened, with small rounded mesial lobe. Merus about 3.5 times as long as broad; externally with oblique depression, extending from near of proximal margin to above middle of segment; dorsal margin almost straight ending in non-acute projection; inferior outer margin serrate, distal end projected as bifurcate obtuse tooth; inferior inner margin strongly serrate, bearing in each pit small spine and long setae ( Fig 5C ), many of them broken off during capture or during manipulation in laboratory; distal margin with acute triangular tooth. Ischium separated from merus by conspicuous deep sulcus, clearly visible in external side, with distal projecting acute tooth and long setae, plus four obtuse protuberances along of ventral margin.

Right first pereopod or minor cheliped slender, covered by numerous long setae, more abundant on fingers ( Figs. 5D–E ), about 4.9 times as long as broad, fingers longer, not gaping, occupying 0.6 of chela; tips well crossing when closed. Palmar chela almost rounded in cross section. Small adhesive plate present on dactylus and upper part of dactylar articulation of palm. External palm with numerous small tubercles on ventral margin; shallow longitudinal palmar groove present; dorsal margin with longitudinal shallow groove, which is visible on both faces; external dactylar articulation with small triangular tooth, and small subacute projection under it. Mesial palm with ventral margin tuberculate; palmar groove shallow; mesial triangular tooth of dactylar articulation well developed; fringe of short stiff setae around adhesive plate, extending to dorsal margin. Cutting edge of both fingers with small serrations and rows of small stiff setae.

Carpus cup shaped, with well developed subtriangular tooth on upper mesial margin, followed by small indentations, similar to tiny furrows, and with additional acute tooth on ventromesial margin. Merus about 3.5 times as long as broad; with dorsal margin convex, smooth; oblique external depression present, extending from near of proximal margin to middle of segment; inferior external margin serrated, ending distally in a non–acute tooth. Inferior internal margin with serrations more pronounced and separated between them, furnished with small spines and long setae ( Fig 5F ), ending distally in small triangular tooth. Ischium separated from carpus for deep sulcus, clearly visible in external side, forming distally and obtuse tooth and furnished with long setae.

Second pereopod slender, reaching beyond distal end of antennular peduncle by proximal articulation of second segment of carpus. Merus slightly longer than ischium. Carpus composed by five segments, proximal the longest; radio of carpal articles 4.0: 2.8: 1.0: 1.0: 1.5 ( Fig. 3E ). Chela small, as long as sum of third and fourth segments, with finger as long as palm, covered by numerous plumose setae, cutting surface of both fingers armed with a sparse row of small and short setae, like spinules.

Third pereopod slender ( Fig. 3F ); ischium armed with small ventrolateral spine; merus unarmed, about of 6.4 time as long as wide; carpus unarmed with upper and inferior distal margins slightly projected; propodus of right leg with six ventral spines plus pair of distoventral spines, situated just at articulation with dactylus, accompanied by bunch of long and short setae; propodus of third left leg with a total of 12 spines on inferior margin, 8 in a row, distal four organized in two pairs, one subdistal and distal pair flanking dactylus ( Fig. 3G ); dactylus conical, with acute tip, near of 0.25 length of propodus, with small bunch of small setae situated dorsally near of tip.

Fourth pereopod almost same as third pereopod; ischium with ventrolateral spine; propodus with six ventral spines and pair of distoventral spines.

Fifth pereopod slender, ischium without spine; propodus with four spines on ventral margin and a pair of distoventral spines ( Fig. 3H ), dense tuft of short setae on ventral third of distal margin; dactylus conical, with acute tip, and small bunch of tiny setae situated dorsally near of tip.

Pleura of abdominal segments 1-4 with broadly rounded margins ( Fig. 2 ). Pleura of second abdominal segment with two separate shallow grooves, proximal one U–shaped, clearly visible in middle part of segment; distal one irregular shaped, well marked extending from middle part to near of inferior margin. Fifth abdominal segment with inferodistal margin slightly acute. Sixth abdominal segment entire without accessory plate in distolateral angle. Sternites smooth, without teeth or spines. Second pleopod with appendix interna, without appendix masculine. Protopods smooth without spines, but distally ending as subacute tooth.

Telson with lateral margins slightly convex, ( Fig. 3I ) near of 1.8 times as long as broad of anterior margin, armed with two pairs of dorsal spines; dorsal surface smooth with no distinct longitudinal median depression.

Distal margin regularly convex, bearing setae and armed with pair of spines at each lateral corner; tiny outer spines barely visible. Uropodal endopod bearing inconspicuous seta-like spines on distal margin and with no distinct inner depression at anterior half. Right uropodal exopod with transverse suture sinusoidal, forming two convex lobes; lateral margin terminating in small acute tooth flanking movable spine, which is longer than lateral tooth. Left uropodal exopod with lateral tooth and movable spine missing.

Color in life. Unknown, but the following coloration was obtained directly from specimen after several days in ice, thawed, and fixed in formalin: antennules and antennae with small bands of orange and red, and abundant small dots light blue. Eyes black. Dorsal part of carapace and abdomen, telson and uropods orange with abundant small light blue dots, telson and uropodal setae reddish. Lateral parts of carapace light orange; pleurae of the abdominal segments light yellow; pleopods with protopodites light yellow ochre, endopodites and exopodites light orange. Pereopods 2-5 light yellow with bands of light brown on each articulation. Carpus, merus and ischium of first pair of legs and third maxilliped orange, with small dots purple on ventral parts. Major and minor chelae yellow ochre with small spots of light blue on upper parts of palms and fingers; ventral part of chelae and tubercles brown reddish and ventral margins light purple, setae light reddish.

Habitat. Alpheus luiszapatai sp. nov. was found in rocky and mud-sandy bottoms, in deep waters from the poorly explored north Pacific coast of Colombia, and apparently shares these substrates with shrimps of the Solenoceridae family, caridean shrimps ( Pandalidae and Hippolytidae ), brachyuran crabs, stomatopods, and several fishes (see Puentes et al. 2007, Tables Nos. 1–2, for a detailed list of the bycatch composition). Despite of its size, apparently is an elusive species, which has not been possible collected again by the several fisheries studies carry on the same area.

Etymology. The new species is named in honor of my friend and colleague Luis “Lucho” Zapata Padilla, for brought the holotype to my attention (plus several samples of interesting crustaceans collected in different parts of Colombian Pacific, still so many of them waiting to be studied), and especially for his constant collaboration, and more important as a public acknowledgment for his valuable scientific contributions to the study and management of Pacific coast of Colombia fisheries.

Remarks. As was mentioned above, the genus A lpheus is one of the most prolific of the order Decapoda . At the species level, its congeners exhibit a highly and intricate morphological diversity, which creates difficulty in taxonomy. For instance, since early species descriptions to facilitate their complicated nomenclature, the genus was initially arranged by Coutière (1899) into five species groups, and later added two more groups ( Coutière 1905). Although these groups have been subsequently determined not to be monophyletic, they have been very useful and used recently in the systematic and descriptions of species of this genus (e.g. Banner & Banner 1981, 1982, 1986; Chace 1972, 1988; Kim & Abele 1988; Bruce 1994; McClure & Wicksten 1997, 2000; Anker & De Grave 2016). In addition, the genus is also well known for the abundant cryptic species which can be only separated by coloration pattern of the body, and detailed molecular analysis, techniques that only recently had been implemented to describe and isolated these complicated species groups (e.g. Knowlton & Mills 1992; Anker et al. 2007a, 2008a, 2008b, 2009, Anker 2012; Bracken-Grissom & Felder, 2014, and Bracken-Grissom et al. 2014).

Alpheus luiszapatai sp. nov. possesses a short rostrum, with smooth, rounded orbital hoods, which lacking teeth or spines, the major chela is slightly rectangular in lateral view, not twisted, and without any sign of sculptures or notches, and the meri of the third to fifth pereopods are smooth without ventrodistal tooth or spines. These external morphological features putatively place Alpheus luiszapatai sp. nov. within the Alpheus brevirostris (Olivier, 1811) species group. This group according with Banner & Banner (1982), holds some of the largest individuals reported from the Alpheidae (e.g. Alpheus stephensoni Banner & Smalley, 1969 , and Alpheus kagoshimanus Hayashi & Nagata, 2000 ), with several of them collected by commercial shrimp trawls. That statement match exactly in the size and method of capture of the new species herein described.

Worldwide the Alpheus brevirostris species group consists of 48 described species (Justin Scioli pers. comm.). In the eastern Pacific only three species pertaining to this group have been previously reported: Alpheus aequus Kim & Abele, 1988 , from Costa Rica to Galapagos Islands, Alpheus naos Anker, Hurt & Knowlton, 2007b , from Panama, and Alpheus hephaestus Bracken-Grissom & Felder, 2014 , from Baja California to Ecuador. Material from eastern Pacific of the last species was misidentified by previous authors as Alpheus floridanus Kingsley, 1878 (see Kim & Abele 1988: 53, and Bracken-Grissom & Felder 2014: 470, for a complete synonymy). Only recently it was separated from the complex group of cryptic species of A. floridanus , using molecular analysis, coloration in life, and a set of a few diagnostic morphological characters.

Alpheus luiszapatai sp. nov. can be easily differentiated from A. aequus (see Kim & Abele 1988; 55, Figs. 23 e–f; Ramos 1995: 145 Fig. 9; Anker et al. 2007b, 17 Figs. 10, 11f) and A. naos (see Anker et al. 2007b, 12, Figs. 7– 9, 11 d–e). In the two previously described species, the major chela is smooth and exhibits a conspicuous distodorsal transverse groove near of dactylar articulation, the area flanking the fossa in both faces of pollex is smooth, without pits or long setae; the minor chela lacks acute tooth on each side of dactylar articulation; the inferior margins of the meri of the major and minor chelipeds are smooth; and the basicerite is unarmed. In Alpheus luiszapatai sp. nov. the distodorsal area of major chela is smooth without any trace of groove and is decorated with small tubercles; the projection flanking the fossa of pollex, in both lateral and mesial faces, is furnished with pits and long setae; the minor chela is armed in each side of dactylar articulation with an acute tooth; the inferior margins of the meri of major and minor chelipeds are crenulated and furnished with small spines and setae; and the basicerite is armed with conspicuous lateral tooth. Furthermore, Alpheus luiszapatai sp. nov. is the largest shrimp with CL exceeding 22 mm, and was recovered from the type locality at depths below 200 m. A. aequus and A. naos are small shrimps with CL not exceeding more than 7 mm, and are typical shallow water species, living from the intertidal zone to recorded depths of 5.0 m.

Alpheus christofferseni Anker, Hurt & Knowlton, 2007b , from Brazil and Alpheus ribeiroae Anker & Dworschak, 2004 , from Cape Verde Island, eastern Atlantic, are two closely related species putatively in Alpheus brevirostris species group, with transverse groove in distodorsal margin of major chela, an external morphological character that quickly separate them from Alpheus luiszapatai sp. nov. These remarks also apply to separate the new species described herein from the Indo–West species of Alpheus brevirostris species group with transverse groove in distodorsal margin of major chela, such as Alpheus bellulus Miya & Miyake, 1969 , Alpheus brevicristatus De Haan, 1844 , Alpheus brevirostris (Olivier, 1811) , Alpheus cythereus, Banner & Banner, 1966 , Alpheus djeddensis, Coutière, 1897 , Alpheus fenneri Bruce, 1994 , Alpheus macellarius Chace, 1988 , Alpheus miersi Coutière, 1898 , Alpheus moretensis Banner & Banner, 1982 , Alpheus novaezealandiae Miers, 1876 . Alpheus platyunguiculatus ( Banner, 1953) , Alpheus pubescens De Man, 1908 , Alpheus rapax Fabricius, 1798 , Alpheus savuensis De Man, 1908 , Alpheus tricolor Anker, 2001 , and Alpheus williamsi Bruce, 1994 (see Banner & Smalley 1969; Banner & Banner 1981, 1982, 1986; Bruce 1994; Anker & De Grave 2016).

Alpheus luiszapatai sp. nov. could be easily differentiated of A. hephaestus by the shape of the major chela. In A luiszapatai sp. nov. the major chela is pear shaped in cross section, and the projections flanking the fossa of the pollex are dorsally furnished with long setae, whose basal pits forming a crenulated dorsal margin. Instead, in A. hephaestus the major chela is ovoid in cross section, and the margins flanking the socket in the fixed finger are practically non–existing, plus the setation is scarce or absent. Additionally, in A. hephaestus the rostral dorsal carina is well extended to middorsal point of carapace, the dactylus of third to fifth pereopods are subspatulate, and the diaeresis on the exopodal uropod is almost straight. In A. luiszapatai sp. nov. the rostral carina is short, poorly developed and not reaching the posterior part of the eyes, the dactylus of third to fifth pereopods are conical, and the diaeresis of the exopodal uropod is clearly sinusoidal. A. hephaestus exhibits a reddish color pattern in life and has been reported from maximum depths less than 100 m; the pattern color in life of A. luiszapatai sp. nov. is more orange-yellowish with small dots blue and purple, and was collected below 200 m depth.

Alpheus paracrinitus Miers, 1881 , a cosmopolitan species broadly distributed around the tropics, and Alpheus rostratus Kim & Abele, 1988 , distributed from California to Galapagos Islands, are a couple of species putatively placed in the Alpheus diadema Dana, 1852 , species group, which share some morphological characters with Alpheus luiszapatai sp. nov. The new species can be clearly separated from A. paracrinitus (see Kim & Abele 1988: 49, Fig. 20; Ramos 1995: 146, Fig. 10), and A. rostratus (see Kim & Abele 1988: 51, Fig. 21; Ramos 1995: 148, Fig. 11) by the following set of characters: in the two former congeners the scaphocerite lateral tooth is long, clearly overreaching the lamella; the inferior margins of meri of both chelipeds are unarmed; and the margins of the major cheliped flanking the fossa of the pollex are smooth, not well developed, and furnished dorsally with short setae. In Alpheus luiszapatai sp. nov. the scaphocerite lateral tooth only slightly overreaches the lamella; the inferior margins of meri of both chelipeds are crenulated with small spines and long setae; and the margins of the major cheliped flanking the fossa of the pollex, are conspicuous, crenulate and furnished with long setae. A. paracrinitus has the distodorsal margin of antepenultimate segment of third maxilliped developed as a rounded projection, but in Alpheus luiszapatai sp. nov. the distal margin of third maxilliped is not projected. A. rostratus has a long rostrum, with the tip almost reaching the distal margin of the first antennular segment. In Alpheus luiszapatai sp. nov. the rostrum is short, barely reaching the middle of the first antennular segment. Both of the former species are small with CL not exceeding 9.0 mm and 7.0 mm respectively, and live in shallow waters, to 5- 6 m. Alpheus luiszapatai sp. nov. is a large, deep water species.

The only other species of Alpheus previously collected from deep waters below 200 m in the eastern Pacific is Alpheus bellimanus Lockington, 1877 , putatively placed in the Alpheus macrocheles (Hailstone, 1835) species group. Recently another deep water snapping shrimp belonging to this group, Alpheus lentiginosus Anker & Nizinski, 2011 , was described from deep waters (336–438 m) in the Gulf of Mexico. Both can easily be differentiated from Alpheus luiszapatai sp. nov., by the same set of characters used to define the artificial species group: the orbital hoods are armed with acute teeth, (in Alpheus luiszapatai sp. nov. the orbital hoods are smooth, without teeth or spines); the major cheliped is twisted and has dorsal and ventral transverse grooves (in Alpheus luiszapatai sp. nov. the major cheliped is not twisted, and lacks transverse grooves); and the dactylus of the minor cheliped is strongly compressed, laminar, with tip acute (in Alpheus luiszapatai sp. nov. the dactylus of minor cheliped is not laminar, and the tip is blunt).

In the western Atlantic the Alpheus brevirostris species group without the distodorsal transverse groove of the major chela contains Alpheus floridanus , Alpheus platycheirus Boone, 1927 , Alpheus ulalae Bracken-Grissom & Felder, 2014 , and Alpheus roblesi Bracken-Grissom & Felder, 2014 (a species also reported from Gabon, Africa, eastern Atlantic). The same set of morphological characteristics used in separating Alpheus luiszapatai sp. nov., from A. hephaestus can be applied to distinguish the new species from these western Atlantic species. Likewise, species of Alpheus brevirostris species group from the eastern Atlantic and Indo Pacific area reported by several authors (e.g. Banner & Banner 1981, 1982, 1986; Chace 1988; Bruce 1994; Hayashi & Nagata 2000; Anker & De Grave 2016), which lack of distodorsal transverse groove of the major chela (e.g. Alpheus acutocarinatus De Man, 1909a , Alpheus arenicolus Banner & Banner, 1983 , Alpheus barbatus Coutière, 1897 , Alpheus compressus Banner & Banner, 1981 , Alpheus digitalis De Haan, 1844 , Alpheus djiboutensis De Man, 1909b , Alpheus explorator Boone, 1935 , Alpheus heterocarpus (Yu, 1935) , Alpheus homochirus (Yu, 1935) , A. kagoshimanus , Alpheus lepidus De Man 1908 , Alpheus leptocheles Banner & Banner, 1975 , Alpheus longiforceps Hayashi & Nagata, 2002 , Alpheus macroskeles Alcock & Anderson, 1899 , Alpheus miersi Coutière, 1898 , Alpheus migrans Lewinsohn & Holthuis, 1978 , Alpheus nonalter Kensley, 1969 , Alpheus notabilis Stebbing, 1915 , Alpheus pustulosus Banner & Banner, 1968 , Alpheus quasirapacida Chace, 1988 , Alpheus sibogae De Man, 1908 , A. stephensoni , and Alpheus talismani Coutière, 1898 ), can be easily separated by the same statements used to discriminate A. hephaestus from Alpheus luiszapatai sp. nov. Although, some species had been collected in deep waters (e.g. A. kagoshimanus ), the new species can be easily separated from it, by the absence of acute tooth on the pterigostomial angle of carapace, the length and shape of major and minor chelipeds, and color in live (see Hayashi & Nagata 2000, Figs. 1–3 , 5 ).

Finally, the unique ornamentation or pseudo dentition, furnished with bunches of long setae, exhibited on top of the lateral and mesial protuberances, flanking the socket of fixed finger of major chela, the tuberculation of both chelae, the presence of lateral and mesial tooth on the dactylar articulation of minor chela, the meri of both chelipeds with inferior margins serrate, furnished with spines and setae, the armature of propodi of third to fifth pereopods, and the diareresis of the exopodal uropod of Alpheus luiszapatai sp. nov., are undoubtedly a combination of morphological characteristics, which can be used to distinguishes this deep water new species from the rest of its congeners. Additionally, the presence of two small triangular teeth on the eyestalk is a condition not reported yet or overlooked for species previously described of Alpheus , although the exception is Alpheus zimmermanni Anker, 2007 (see Anker 2007, Fig. 1c ), with a single subtriangular tubercle close to the eye. The only other species of the family Alpheidae , I am aware, that shows remarkably something similar, is presented in the eyes of the mono generic micro shrimp Acanthanas pusillus Anker, Poddoubtchenko & Jeng, 2006 (see Figs. 1 , 2a– e ), with one tooth on the cornea and another tooth in the base of eyestalk.

Figures

FIGURE 1. Map of type locality of Alpheusluiszapatai sp. nov., Arusí, Chocó, Pacific coast of Colombia.

FIGURE 2. Alpheus luiszapatai sp. nov. holotype, female CL 22.9 mm, Arusí, Chocó, Pacific coast of Colombia (USNM 1468999):habitus, lateral view. Scale = 10 mm.

FIGURE 3. Alpheus luiszapatai sp. nov. holotype, female CL 22.9 mm, Arusí, Chocó, Pacific coast of Colombia (USNM 1468999): A, anterior part of the carapace and cephalic appendices, dorsal view; B, same, lateral view; C, same, infero-lateral view; D, first antennular segment, lateral view; E, left second pereopod, lateral view; F, right third pereopod, lateral view; G, left third pereopod, detail of distal propodus and dactyl, mesial view; H, left fifth pereopod, detail of distal propodus and dactylus, mesial view; I, telson and uropods, dorsal view.Scales A, B, E, F, I = 5 mm, C = 2 mm, D = 2.5 mm, G, H = 1mm.

FIGURE 4. Alpheus luiszapatai sp. nov. holotype, female CL 22.9 mm, Arusí, Chocó, Pacific coast of Colombia (USNM 1468999): Left side mouthparts, lateral view: A, left mandible; B first Maxilla; C, second maxilla; D, first maxilliped; E, second maxilliped; F, third maxilliped. Scales A-E = 1 mm, F = 5 mm.

FIGURE 5. Alpheus luiszapatai sp. nov. holotype, female CL 22.9 mm, Arusí, Chocó, Pacific coast of Colombia (USNM 1468999):A, major cheliped, external view; B, same, mesial view; C, merus detail; D, minor cheliped, externalview; E, same, mesial view; F, merus detail; G, fixed finger and dactylus, mesial view, detail, H, dactylus, external view.Scales A, B, D, E = 5 mm, C, F, G = 1 mm, H = 2 mm.