Description of Alpheopsis gorei sp. nov., a mesophotic alpheid shrimp from the western Atlantic (Decapoda: Caridea)

Abstract

A new mesophotic alpheid shrimp, Alpheopsis gorei sp. nov., is described from several offshore localities in the northern and north-eastern Gulf of Mexico off Texas, Louisiana and western Florida. However, the distribution range of the new species extends to the Atlantic coast of Florida, with a previous record from deep-water reefs off Key Largo, under A. trispinosa Stimpson, 1860. The presently known bathymetric range of A. gorei sp. nov. is 42.1-126.2 m and the species appears to be free-living, mainly among coralline nodules and in crevices of deep coral rubble. The new species is morphologically closest to the eastern Altantic A. africana Holthuis, 1952 and A. azorica Anker, Poddoubtchenko & d’Udekem d’Acoz, 2005, the eastern Pacific A. equidactylus Lockington, 1877, and the Indo-West Pacific A. trispinosa, A. garricki Yaldwyn, 1971 and A. keijii Anker, 2007, differing from each of them by at least two morphological characters.

Keywords:
Atlantic Ocean; USA; Gulf of Mexico; Florida; Crustacean; Deep-water shrimp; Alpheidae; ROV; ARMS

INTRODUCTION

The Alpheopsis trispinosa (Stimpson, 1860) species group first proposed by Coutière (1899) was recently reviewed by Anker (2017a), who recognised 10 species: A. trispinosa, A. equidactylus Lockington, 1877, A. chilensis Coutière, 1897, A. shearmii (Alcock & Anderson, 1899), A. africana Holthuis, 1952, A. diabolus Banner, 1956, A. garricki Yaldwyn, 1971, A. azorica Anker, d’Udekem d’Acoz & Poddoubtchenko, 2005, A. keijii Anker, 2017 and a species provisionally listed as A. sp. aff. trispinosa = A. trispinosa sensu Gore (1981). As argued by Anker (2017a), the inadequately described A. garricki, although morphologically barely distinguishable from A. trispinosa, should be treated as a valid species until more evidence (morphological and molecular analyses) becomes available. The last of the above-listed species, A. sp. aff. trispinosa, which was originally reported by Gore (1981) as A. trispinosus based on material from the Florida Keys, remained undescribed, until now. Examination of material collected in various parts of the Gulf of Mexico between 2018 and 2024, by (i) deep-water scuba divers using diving rebreathers for retrieval of debris (DEB), (ii) remotely operated underwater vehicles (ROV), (iii) autonomous reef monitoring structures (ARMS), and (iv) box dredges, confirmed that the western Atlantic species is indeed new to science. In the present study, this species is finally described and illustrated, based on the recently collected material, with the original figures provided by Gore (1981: fig. 3) serving as complementary illustrations.

MATERIAL AND METHODS

The type material of the new species is deposited in the collections of the National Museum of Natural History, Smithsonian Institution, Washington DC, USA (USNM). The material originally reported by Gore (1981) was originally deposited in the collection of the Indian River Coastal Zone Museum at Link Port, Fort Pierce, FL, USA (IRCZM), which was later integrated into Florida Atlantic University (FAU) Harbor Branch Oceanographic Institute; however, its current condition remains unknown.

For the samples collected by DEB and ROV, each specimen (or lot of specimens) received a unique field collection number (fcn) connected to station data, where SIMDBC stands for Smithsonian Institution (SI) / Mesophotic Deep Benthos Communities (MDBC) of NOAA, followed by expedition code, which includes the name of the research vessel, for instance, R/V Island Intervention (II) or Pisces (PC), expedition year and leg (first or second), full date, and number of debris retrieval dive (DEB) or remote operated vehicle dive (ROV). ARMS and dredge samples received unique SH- and SJP- codes.

Carapace length (cl) was measured along mid-dorsal line from the rip of the rostrum to the posterior margin of the carapace. P1 is abbreviation for the first pereiopod (cheliped).

Systematics

Alpheidae Rafinesque, 1815

Alpheopsis Coutière, 1897

Alpheopsis gorei sp. nov.

(Figs. 1-3)

Figure 1
Alpheopsis gorei sp. nov., paratype, ov. female, cl 3.9 mm, off Texas, USA (USNM 1716684) [A-K]; holotype, male, cl 4.1 mm, off Texas, USA (USNM 1720637), [L]; paratype, male, cl 3.6 mm, off Mississippi, USA (USNM 1552850) [M-S]; (A) frontal region, dorsal; (B) same, lateral view; (C) fourth (posterior part), fifth and sixth pleonites, lateral; (D) third maxilliped, lateral; (E) same, tip of ultimate article, mesial; (F) second pereiopod, lateral; (G) third pereiopod, lateral; (H) same, propodus (distal part) and dactylus, mesial; (I) fourth pereiopod, lateral; (J) fifth pereiopod (ischium unarmed), lateral; (K) uropod, dorsal; (L, M) rostro-orbital region of carapace, dorsal; (N) telson, dorsal, (O) antennule, lateral; (P) fifth pereiopod (ischium armed), lateral; (Q) same, setobranch with detached strap-like epipod of fourth pereiopod, lateral; (R) second pleopod, anterior; (S) same, appendices masculina and interna, anterior. All scales in mm.

Figure 2
Alpheopsis gorei sp. nov., paratype, ov. female, cl 3.9 mm, off Texas, USA (USNM 1716684) [A-D]; holotype, male, cl 4.1 mm, off Texas, USA (USNM 1720637), [E]; (A) left cheliped, mesial; (B) same, lateral; (C) same, carpus and chela, ventrolateral; (D) same, dorsomesial; (E) same, lateral. All scales in mm.

Figure 3
Alpheopsis gorei sp. nov., paratype, ov. female, cl 3.5 mm, off Louisiana, USA (USNM 1745065), shrimp alive, dorsal. Photograph by Sarah Tweedt.

• Alpheopsis trispinosusGore, 1981: 149, fig. 3; Felder et al., 2009: 1056.

• Alpheopsis sp. aff. trispinosa - Anker, 2017a: 578, 579 (key).

Type material: Holotype: male (cl 4.1 mm), USNM 1720637, USA, Texas, Flower Garden Banks National Marine Sanctuary, East Flower Garden Bank, 27°53′52.8″N 93°35′56.4″W, recovered debris (TABS buoy), depth: 75.5-88.5 m, 30.07.2024 [fcn SIMDBC_01083 / II2402_20240730_07_DEB01]. Paratypes: 1 ov. female (cl 4.9 mm), USNM 1720635, same collection data as for holotype [fcn SIMDBC_01081 / II2402_20240730_07_DEB01]; 1 female (cl 2.3 mm), USNM 1716685, USA, Texas, Flower Garden Banks National Marine Sanctuary, McGrail Bank, McGrail South Limb, centroid 27°57′43.2″N 93°34′55.2″W, ROV, depth: 126.2 m, 27.07.2024 [fcn SIMDBC_00903, II2401_20240727_05_ROV32]; 1 ov. female (cl 3.9 mm, dissected), USNM 1716684, same collection data [fcn SIMDBC_00903-B, II2401_20240727_05_ROV32]; 1 male (cl 3.4 mm), USNM 1745077, USA, Texas, Flower Garden Banks National Marine Sanctuary, McGrail Bank, 27°57′25.8″N 92°34′52.7″W, ARMS, depth: 85 m, 10.08.2021 [fcn SH20632]; 1 male (cl 2.9 mm), USNM 1745078, same collection data [fcn SH20662]; 1 male (cl 3.5 mm), 1 ov. female (cl 3.5 mm), USNM 1720687, USA, Texas, Flower Garden Banks National Marine Sanctuary, Elvers Bank, Swiftia Ranch, 27°51′07.2″N 92°55′12.0″W, ROV, depth: 93.1-97.2 m, 01.08.2024 [fcn SIMDBC_01133, II2402_20240801_04_ROV1]; 1 ov. female (cl 3.5 mm), USNM 1745065, USA, Louisiana, Diaphus Bank 80 km W of Mississippi Trough, 28°05′17.6″N 90°34′12.5″W, ARMS, depth: 81 m, 08.08.2021 [fcn SH20111]; 1 male (cl 3.6 mm, missing both P1), USNM 1552850, USA, Louisiana, off Caillou Bay, centroid 28°05.55′N 91°01.30′W, R/V Pelican, NSF-RHODOLITH_07, 05-04-18-04 box dredge, depth: 70 m, shell hash/fine rubble, leg. S. Pecnik et al., 04.05.2018 [fcn SJP188]; 1 female (cl 2.6 mm), USNM 1693848, USA, Florida, off Panama City, sta. WFL13, centroid 29°30′32.3″N 86°08′40.6″W, ROV, depth: 85.7 m, base of gorgonian (Thesea nivea), 25.07.2023 [fcn SIMDBC_00501 / PC2302L3_20230725_01_ROV37].

Additional material: 2 mutilated specimens (cl 3.4, 3.5 mm, 2 loose P1 present in the vial), USNM 1741138, USA, 2528G, no further data (probably northern Gulf of Mexico off USA), don. D.L. Felder, 11.1977 (identified as A. trigonus).

Material listed by Gore (1981) [not examined]: 1 ov. female (cl 5.1 mm), IRCZM 89:4667, USA, Florida, Key Largo Marine Sanctuary, Elbow Reef, sta. I-688, 25°07.79′N 80°14.32′W, 56.4 m, manipulator, sponge with worm snail (Siliquaria modesta) colony, 06.06.1979; 2 males (cl 3.8 mm, 3.6 mm), 1 female (cl 2.3 mm), IRCZM 89:4667, same collection data; 1 male (cl indet.), IRCZM 89:4668, USA, Florida, Key Largo Marine Sanctuary, French Reef, sta. I-679, 25°01′12.0″N 80°20′22.8″W (tentative coordinates based on location and depth), 42.1-76.2 m, manipulator, in coralline rocks, 03.06.1979 [specimen illustrated by Gore (1981: fig. 3)].

Description: Small-sized alpheid shrimp (cl < 5.0 mm). Carapace sparsely covered with erect setae; rostrum 1.4-2 times as long as wide, slightly elevated, tip acute, reaching 0.3-0.5 length of first article of antennular peduncle; orbital hoods feebly swollen; orbital teeth acutely projecting, subtriangular, with wide base; pterygostomial angle poorly defined, broadly rounded (Fig. 1A, B). First to fourth pleura rounded to slightly angular posteroventrally; fifth pleuron with posteroventral angle subacutely projecting; sixth pleonite with subquadrate posterior lobe and triangular articulated plate (Fig. 1C). Telson relatively broad, tapering distally, about 1.7 times as long as greatest width; dorsal surface with two pairs of spiniform setae inserted at some distance from lateral margin, at about 0.5 and 0.7-0.8 telson length, respectively; posterior margin broadly rounded, with two pairs of spiniform setae, mesial stouter and three times as long as lateral, and with three pairs of plumose setae between mesial spiniform setae (Fig. 1N).

Eyes completely concealed by orbital hoods, not visible in dorsal and lateral views; eyestalk with well-pigmented cornea (Fig. 1A, B). Each epistomial sclerite with small blunt process.

Antennular peduncles moderately slender; stylocerite slender, with acute tip reaching (sometimes slightly) beyond distal margin of first article; ventromesial carina with strong, anteriorly directed tooth; second article about 1.5 times as long as wide; lateral flagellum biramous; fused portion short, with at least five subdivisions in adult specimens; accessory ramus well developed, with at least four groups of aesthetascs (Fig. 1A, B, O). Antenna with basicerite relatively small, armed with sharp tooth on distal ventrolateral margin; scaphocerite ovate, with sharp distolateral tooth reaching far beyond anterior margin of blade but not exceeding distal margin of antennular peduncle, lateral margin straight to feebly concave; carpocerite overreaching distolateral tooth of scaphocerite, usually reaching to end of antennular peduncle (Fig. 1A, B).

Mouthparts typical for genus in external view (not illustrated). Third maxilliped slender, pediform; coxa with distally bilobed lateral plate above strap-like epipod; penultimate article about 2.3 times as long as distal width; ultimate article strongly tapered distally, tip armed with two slender spiniform setae; exopod well developed, reaching or exceeding distal margin of antepenultimate article; arthrobranch small, with few lamellae (Fig. 1D, E).

Chelipeds typically subequal in size, sometimes somewhat unequal (difference in volume not exceeding 20%), subsymmetrical in shape, carried extended; ischium unarmed, with strongly oblique articulation at distal margin; merus slender, unarmed, with dorsal margin about 3.7-4.1 times as long as maximum width, distomesial angle blunt; carpus very short, cup-shaped, with rounded distal lobes; chela moderately slender, with fingers about half as long as palm; palm about 2.7 times as long as maximal height (width) in largest specimens, closer to 3.0 in smaller specimens, subcylindrical in cross-section, with deep longitudinal groove on dorsal surface, starting at about palm mid-length and fusing with short transverse groove close to dactylar articulation; ventral surface of palm proximal to carpus with small tubercle; fingers slightly twisted, not gaping when closed, with blunt tips, tip of dactylus reaching somewhat beyond that of pollex; cutting edge of pollex with three low blunt teeth in proximal half, sometimes with four teeth extending to 0.6 of pollex length; cutting edge of dactylus with one small tooth fitting into gap between two larger teeth of pollex (Fig. 2; see also Fig. 3).

Second pereiopod slender; ischium subequal to merus in length; carpus with five subarticles, first longer than sum of remaining four; chela significantly longer than distal-most carpal subarticle, with fingers much longer than palm (Fig. 1F). Third pereiopod slender; ischium with two spiniform setae on ventrolateral surface; merus at least seven times as long as wide, unarmed; carpus 0.7 length of merus, unarmed; propodus with row of six or seven slender spiniform setae along ventral margin and two longer spiniform setae distally, adjacent to dactylar base; dactylus about 0.35 length of propodus, slender, simple, subconical, gradually curving distally (Fig. 1G, H). Fourth pereiopod similar to third pereiopod in length, article proportions and armature, slightly more slender (Fig. 1I). Fifth pereiopod much more slender than fourth pereiopod; ischium usually with one spiniform seta on ventrolateral surface, sometimes unarmed; merus about eight times as long as wide; carpus 0.8 length of merus; propodus with row of five to seven spiniform setae, one longer distal spiniform seta adjacent to dactylar base, and well-developed grooming brush composed of numerous rows of microserrulate setae increasing in length distally (Fig. 1J, P, Q).

Male second pleopod with slender appendix masculina reaching far beyond appendix interna, but not reaching tip of endopod; apex with several long stiff setae (Fig. 1S). Uropod with lateral lobe of protopod distally bidentate, lateral tooth stronger; exopod broadly ovate, with subacute distolateral tooth adjacent to prominent, elongate spiniform seta; diaresis sinuous, with strong subtriangular tooth mesially flanking spiniform seta; endopod ovoid, without specific features (Fig. 1K).

Gill/exopod formula: Five pleurobranchs on body wall above first to fifth pereiopods; five strap-like epipods on coxae of third maxilliped and first to fourth pereiopods; five setobranchs on coxae of first to fifth pereiopods; one arthrobranch at base of third maxilliped; podobranch absent; three exopods on first to third maxilliped (Figs. 1D, F, I, P, Q, 2B).

Colour pattern: Translucent with bright red transverse bands on carapace and pleon, distributed as following: one partly interrupted band across middle of carapace, one broad band across posterior quarter of carapace, and six broad bands on pleon, one per pleonite, occupying posterior half of pleonite or (widest bands) posterior two-thirds of its surface, first and second band dividing ventrally, forming inversed U; carapace also with smaller red streaks and patches on anterior flanks and around rostro-orbital area; antennules and antennae speckled with red chromatophores, flagella pale orange; chelipeds mostly speckled with red chromatophores, propodo-dactylar articulation area more orange, occlusal margins of fingers and fingertips transparent yellow, amber-like; second pereiopods and walking legs (third to fifth pereiopods) with transverse bands; telson and uropods red on most of posterior portion, translucent proximally except for red uropodal protopod; freshly laid eggs bright yellow (Fig. 3).

Etymology: The new species is named after the decapod taxonomist, marine ecologist and biogeographer, Dr. Richard H. Gore, who first reported it from Florida (Gore, 1981, as A. trispinosus).

Distribution: Western Atlantic: presently known from several offshore banks of Texas-Louisiana Shelf and West Florida Shelf in the northern and north-eastern Gulf of Mexico, and two offshore reefs on the Atlantic side of the northern Florida Keys (Fig. 4); specific localities include Texas: Flower Garden Banks National Marine Sanctuary (East Flower Bank, McGrail Bank, Elvers Bank); Lousiana: off Caillou Bay, Florida: off Panama City, off Key Largo (Elbow and French Reefs) (Gore, 1981; present study); records from central-eastern coast of Florida (off Fort Pierce and Wabasso) require confirmation (see below).

Figure 4
Presently known distribution of Alpheopsis gorei sp. nov. in the Gulf of Mexico and Atlantic Ocean. Type locality is indicated with a red dot; other localities are marked with yellow dots; records off central-eastern coast of Florida marked with yellow dots and “?” require confirmation. Map prepared using Google Earth [https://earth.google.com/web].

Ecology: Deep subtidal and mesophotic species, presently known bathymetric range: 42.1-126.2 m; free-living among coralline nodules and conglomerates (rhodoliths), in crevices of or under dead coral fragments and other debris; one specimen was found near the base of a gorgonian (Thesea nivea Deichmann), whilst another one came from a sponge with a colony of worm snails (Siliquaria modesta Dall) (Gore, 1981).

Remarks:Alpheopsis goreisp. nov. was first reported by Gore (1981) as A. trispinosus, based on material from the Atlantic side of Florida Keys. Within the A. trispinosa group, the new species is morphologically most similar to two other Atlantic congeners, A. africana and A. azorica, the eastern Pacific A. equidactylus, and the Indo-West Pacific A. trispinosa, A. garricki and A. keijii. The remaining species of the A. trispinosa group, viz. A. chilensis, A. shearmii and A. diabolus, present a suite of more distinctive characters (Banner & Banner, 1977; Retamal, 1981; Banner, 1956; Carvacho et al., 2000) and appear to be more distantly related to A. gorei sp. nov.

The new species can be separated from A. trispinosa and A. garricki by the much more slender dactylus of the third pereiopod, about 7.5 times as long as proximal width vs. at most 3.5 times as long as proximal width in A. trispinosa and A. garricki (cf. Fig. 1G; Gore, 1981: fig. 3E, F; Banner & Banner, 1973: fig. 14h, i; Anker, 2017a); from A. trispinosa, A. azorica and A. equidactylus by the much shorter stylocerite, which is only slightly overreaching the distal margin of the first article of the antennular peduncle vs. reaching almost to the mid-length of the second article in A. trispinosa and A. azorica, and almost to the end of the second article in A. equidactylus (cf. Fig. 1A; Holmes, 1900: 187; Gore, 1981: fig. 3A; Banner & Banner, 1973: fig. 14a; Anker et al., 2005: fig. 1b, c); from A. azorica by the presence of strap-like epipods on the coxae of the third maxilliped and first to fourth pereiopods vs. on the coxae of the third maxilliped and first and second pereiopods in A. azorica (cf. Fig. 1D, F, G, I; Anker et al., 2005: 102); from A. azorica and A. africana by the subequal chelipeds, which are distinctly unequal in the other two species (cf. Fig. 2; Gore, 1981: 149; Anker et al., 2005: figs. 1a, 2, 6; see also Fig. 5A, B); from A. africana and A. keijii by the somewhat stouter antennular peduncles and less sinuous diaeresis of the uropodal exopod (cf. Fig. 1A, K; Gore, 1981: fig. 3A, G; Anker et al., 2005: fig. 5a, j; Anker, 2017a: fig. 1a, k); from A. equidactylus by the absence of “spinules” (small spiniform setae?) on the distal margin of the first and second articles of the antennular peduncle, which are present in the Californian species according to Wicksten (1992: 55); and from A. keijii by the much stronger dentition on the cheliped fingers (cf. Fig. 2; Gore, 1981: fig. 3B, C; Anker, 2017a: figs. 2, 3b). The above comparison indicates that the two species that are morphologically and presumably also phylogenetically closest to A. gorei sp. nov. are A. equidactylus (Fig. 5C, D) and A. africana, followed by A. azorica (Fig. 5A, B).

Figure 5
Two species of the Alpheopsis trispinosa Stimpson, 1860 group closely related to Alpheopsis gorei sp. nov.: Alpheopsis azorica Anker, d’Udekem d’Acoz & Poddoubtchenko, 2005 [A, B] and A. equidactylus Lockington, 1877 [C, D]; (A) specimen of undetermined sex (probably male) from Tenerife Island, Canary Islands, Spain, not deposited; (B) specimen of undetermined sex (probably male) in situ, Canary Islands, Spain; (C) specimen of undetermined sex (probably male) in situ, off Redondo Beach, southern California, USA; (D) specimen of undetermined sex (probably male) from Santa Cruz Island, southern California, USA (not deposited). Photographs by Keider Neves (A), RedPROMAR (B), Phil Garner / Southern California Marine Life (C) and Greg Jensen (D).

Alpheopsis goreisp. nov. can be easily distinguished from A. chilensis by the sharp orbital teeth, which are blunt in A. chilensis, as well as by the much shorter stylocerite, which is slightly overreaching the distal margin of the first article of the antennular peduncle in the new species vs. reaching almost to the distal margin of the second article in A. chilensis (cf. Fig. 1A; Gore, 1981: fig. 3A; Coutière 1899: fig. 27; Carvacho et al., 2000: fig. 1a); from A. shearmii by the non-swollen orbital hoods covering the eyes, latter also with relatively larger corneas, and much broader telson (cf. Fig. 1A, B; Gore, 1981: fig. 3A; Banner & Banner, 1977: 1a, e); and from A. diabolus by the cheliped dactylus not reaching far beyond the tip of the pollex and not strongly twisted as in A. diabolus, the third to fifth pereiopods terminating in simple dactyli, which are distinctly biunguiculate in A. diabolus, and much narrower telson, with a very different disposition of the two pairs of dorsal spiniform setae (cf. Figs. 1G, I, J; Gore, 1981: fig. 3E, F; Banner, 1956: fig. 3G, H, i).

The degree of the cheliped asymmetry in the A. trispinosa group seems to be variable, although most species have similar right and left chelipeds, e.g., they are more or less equal in size and symmetrical in shape. The only exceptions are A. africana and A. azorica, in which in all known specimens, the chelipeds are markedly unequal in size, with the minor chela also being noticeably more slender (Holthuis, 1952; Anker et al., 2005; see also Fig. 5A, B). In A. equidactylus, the degree of asymmetry between the right and left chelipeds remains unclear. Holmes (1900: figs. 45, 46) illustrated a major cheliped (palm length: 7 mm) and a much smaller minor cheliped (palm length: 5 mm) for his specimen of A. equidactylus from Santa Barbara, California (figures republished by Schmitt, 1921: fig. 53), and discussed the possible misinterpretation of the single cheliped present in the dried type specimen from Monterey by Lockington (1877). However, the colour photograph of A. equidactylus published by Anker (2017a: fig. 4d) shows a shrimp with subsymmetrical and only slightly unequal chelipeds, with the minor (left) cheliped palm being at most 15% smaller by volume than the major (right) cheliped, which is also the case of some paratypes of A. gorei sp. nov. (Fig. 3), whereas the chelipeds of another recently photographed specimen of the Californian species are equal and symmetrical (Fig. 5D). The chelipeds of the holotype of A. garricki are equal in size and symmetrical in shape (Anker, 2017a), as in A. trispinosa. As noted by Anker (2017a), both A. equidactylus and A. garricki require full redescriptions (if the latter is not shown to be conspecific with A. trispinosa), including more data on the relative size and degree of asymmetry of their chelipeds.

The description of A. gorei sp. nov. confirms the consistency of the colour pattern type in the A. trispinosa group: all species with known colour patterns display red or dark reddish bands across the carapace and pleon (Figs. 3, 5; see also Anker, 2017a: fig. 4). This is in sharp contrast to the morphologically more heterogeneous A. aequalis Coutière, 1897 group, in which species can be uniformly white, orange, or variously red-banded (e.g., Anker, 2015, 2017b; Anker et al., 2016; pers. obs.).

In his account of A. trispinosus, Gore (1981) listed five additional incomplete specimens collected with a Smith-MacIntyre grab off central-eastern coast of Florida, more precisely off Fort Pierce (27°44.3′N, 79°58.0′W, 72 m) and Wabasso (27°52.5′N, 79°57.5′W, 75-98 m). He noted that they “possess a trispinose front and lack carapacial carinae … unfortunately, all are missing chelipeds so specific identification remains tentative.” The presence of A. gorei sp. nov. off central-eastern Florida is likely due to the proximity (300 km) of these collection sites to the confirmed Atlantic localities of the new species off Key Largo and similar depth range. However, it must be noted that in A. chalciope De Man, 1910, which was unknown to Gore (1981) as it was reported for the first time from the western Atlantic by Anker et al. (2016) [as A. chalciope sensu lato], the carapace also lacks carinae and is armed with two acute orbital teeth. In addition, some Brazilian specimens referred to A. chalciope sensu lato in Anker et al. (2016) were collected between 60 m and 128.9 m, i.e., at similar depths as A. gorei sp. nov. in the Gulf of Mexico and off Florida.

Key to the presently known species of the Alpheopsis trispinosa ( Stimpson, 1860) group (modified from Anker, 2017a)

• 1A. Dactylus of 3^rd to 5^th pereiopod binguiculate; cheliped dactylus distinctly longer than pollex, distally curved and strongly twisted………………………………………………………………………………………………………………………………………………………………………..A. diabolus [W and C Pacific: Taiwan to Hawaii and French Polynesia, 0-20 m]

• 1B. Dactylus of 3^rd to 5^th pereiopod simple; cheliped dactylus subequal to pollex, distally not strongly curved or twisted…………………………………………………….2

• 2A. Stylocerite reaching or almost reaching distal margin of 2^nd article of antennular peduncle…………………………………………………………………………...3

• 2B. Stylocerite reaching at most to mid-length of 2^nd article of antennular peduncle…..5

• 3A. Orbital teeth rounded, obtuse in adults (comparatively large species, cl > 5 mm)…..A. chilensis [SE Pacific: Peru and Chile, including Juan Fernández Is., 0-20 m]

• 3B. Orbital teeth sharp in adult and juveniles…………………………………………..4

• 4A. Third pereiopod propodus at most 8 times as long as wide (distal margin of 1^st article of antennular peduncle with spinules according to Wicksten (1992))……………………………………………………………………………………………………………………………………………………………………………………………………………………A. equidactylus [NE Pacific: California, 0-20 m]

• 4B. Third pereiopod propodus slightly more than 8 times as long as wideA. garricki [SW Pacific: New Zealand, including Chatham Is., 36-200 m]

• 5A. Orbital hoods conspicuously swollen (cornea relatively small)A. shearmii [NW Indian Ocean: Arabian Sea, 786 m]

• 5A. Orbital hoods not particularly swollen……………………………………………..6

• 6A. Second article of antennular peduncle 1.5 to 1.8 times as long as wide……………7

• 6B. Second article of antennular peduncle at most 1.2 times as long as wide………….8

• 7A. Stylocerite barely overreaching distal margin of 1^st article of antennular peduncle; chelipeds subequal in size; cutting margin of cheliped pollex and dactylus with 2 and 1 minute teeth, respectivelyA. keijii [Indo-West Pacific: Japan to Papua New Guinea and Madagascar, 90-487 m]

• 7B. Stylocerite reaching distinctly beyond distal margin of 1^st article of antennular peduncle; chelipeds unequal in size; cutting margin of cheliped pollex with 2 small teeth, that of dactylus unarmedA. africana [SE and E Atlantic: Namibia, Angola, Cape Verde? 150-185 m]

• 8A. Stylocerite reaching mid-length of 2^nd article of antennular peduncle; dactylus of 3^rd to 5^th pereiopod stout, about 2.5 times as long as proximal width……………………………………………………………………………………………………………………………………………………………………………..A. trispinosa [S Indo-West Pacific: S and E Australia, Tasmania, 11-135 m]

• 8A. Stylocerite not reaching mid-length of 2^nd article of antennular peduncle; dactylus of 3^rd to 5^th pereiopod slender, more than 3 times as long as proximal width……….9

• 9A. Stylocerite reaching mid-length of 2^nd article of antennular peduncle; rostrum overreaching distal margin of 1^st article of antennular peduncle; strap-like epipods on 3^rd maxilliped and 1^st and 2^nd pereiopodsA. azorica [NE and E Atlantic: Azores, Cape Verde, 20-91 m]

• 9B. Stylocerite slightly overreaching distal margin of 1^st article of antennular peduncle; rostrum not reaching mid-length of 1^st article of antennular peduncle; strap-like epipods on 3^rd maxilliped and 1^st to 4^th pereiopodsA. gorei sp. nov. [NW Atlantic: Texas to Florida, 42-126 m]

DATA AVAILABILITY:

The contents underlying the research text are included in the manuscript.

Acknowledgments:

The author thanks Sarah Tweedt, Christopher Meyer, Paula C. Rodriguez-Flores, Martha Nizinski and all the staff of the Department of Invertebrate Zoology of USNM for their hospitality and assistance during his short visits in 2024 and 2025. Colour photographs in Figs. 3, 5 were provided by Sarah Tweedt (USNM), Greg Jensen (University of Washington), Keider Neves (Biosfera 1, Associação para a Defesa do Meio Ambiente), RedPROMAR (https://redpromar.org), a marine life monitoring and surveillance network led by the Government of the Canary Islands, authorised by the group supervisor, José Antonio González (Universidad de Las Palmas de Gran Canaria), and Phil Garner / Southern California Marine Life (https://www.inaturalist.org/photos/8921928).

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• AI USE:
  No AI tools were used in this manuscript.
• FUNDING:
  Funding to conduct this study was provided by USNM and KAUST baseline research funds awarded to Susana Carvalho and Francesca Benzoni.

• Edited by:
  Marcos Domingos Siqueira Tavares

Publication Dates

• Publication in this collection
  30 Mar 2026
• Date of issue
  2026

History

• Received
  13 June 2025
• Accepted
  10 Oct 2025
• Published
  20 Feb 2026