Alpheus lentiginosus
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Ordo: Decapoda
Familia: Alpheidae
Genus: Alpheus
Name
Alpheus lentiginosus Anker, Arthur, 2011 – Wikispecies link – Pensoft Profile
- Alpheus lentiginosus Anker, Arthur, 2011, Zootaxa 2925: 50-55.
Materials Examined
Type material.Holotype: male (CL 7.9 mm), USNM1145505, North Atlantic Ocean, Gulf of Mexico, 188.8 km south of Louisiana, expedition USGS DISCOVRE GOM, cruise JSLII-09- GOM, vessel Seward Johnson – DSR/V Johnson Sea Link II, Sta. JSL 3726, 28° 11 ’ 41 ”N89 ° 47 ’ 59 ”W (28.1947250, - 89.7999167), Lease Block MC 751, Bucket 1, depth 434–438 m, patch reef on soft bottom, base of Lophelia pertusa, S.W. Ross et al., 19 September 2009. Paratype: female (CL 10.1 mm), USNM1145818, North Atlantic Ocean, Gulf of Mexico, 261.82 km south of Louisiana, expedition USGS-GOM-Lophelia I, cruise USGS-GOM, vessel Seward Johnson – DSR/V Johnson Sea Link I, Sta. JSL 4745, 29°05’ 53 ”N88 ° 23 ’06”W (29.0979533, -88.3849800), Lease Block VK 906 / 862, Bucket 11, depth 336 m, K. Sulak et al., 30 July 2004.
Description
Description. Body moderately slender, laterally not compressed. Carapace glabrous, without marked sculpture; frontal margin with well-developed rostrum and orbital teeth; rostrum subtriangular, distally acute, longer than as wide, without setae; tip not reaching half-length of first article of antennular peduncle; rostral carina not distinct; orbital teeth in marginal position, narrow, slightly directed mesially, distally acute, shorter than rostrum; margin between orbital teeth and rostrum almost straight, transversely oblique; orbital hoods moderately swollen, complete, enclosing eyes from all sides (Fig. 1 a, b); orbito-rostral process simple. Pterygostomial angle rounded, not protruding anteriorly (Fig. 1 b); cardiac notch deep. Abdominal somites with posteroventral margins broadly rounded to somewhat angular; sixth somite without articulated flap, distodorsal margin bluntly projecting on each side of telson. Telson subrectangular, tapering posteriorly, more than twice as long as wide at base; lateral margins slightly and broadly convex; dorsal surface with two pairs of strong spiniform setae inserted far from lateral margin, first pair anterior to half-length of telson, second pair between 2 / 3 and 3 / 4 length of telson; posterior margin broadly convex, with two pairs of slender posterolateral spines, mesial twice as long as lateral, margin between spines without spiniform setae (Fig. 1 k); anal tubercles well developed. Eyes with well-developed, normally pigmented corneas; anteromesial margin protruding as large bump (Fig. 1 l). Ocellar beak acute, rather small, not visible in lateral view. Epistomial sclerites without acute projections. Antennular peduncle slender; stylocerite well developed, with acute tip, falling short of distal margin of first article; ventromesial carina with subtriangular tooth as illustrated (Fig. 1 c); second article much longer than dorsally visible portion of first article, about three times as long as wide; third article shortest, about one third length of second (Fig. 1 a); lateral flagellum with groups of aesthetascs starting from 10 th article, aesthetascs longer and more dense distally, secondary ramus composed of at least two articles. Antenna with basicerite terminating in stout sharp distoventral tooth; carpocerite slender, exceeding both scaphocerite and antennular peduncle; scaphocerite with shallowly concave lateral margin; distolateral tooth stout, reaching far beyond distal margin of blade, and also reaching slightly beyond distal margin of antennular peduncle (Fig. 1 a, b, m). Mouthparts not dissected, appearing genus-typical in external observation; mandible with biarticulated palp, incisor process with distal margin furnished with seven subtriangular teeth, most-anterodistal margin without teeth. Third maxilliped fairly slender; coxa with lateral plate bluntly produced dorsally, distal margin with row of setae; exopod long, overreaching distal margin of antepenultimate article; antepenultimate article somewhat flattened, subtriangular in cross-section, ventral margin setose; distodorsal margin with one particularly long thick seta; penultimate article subcylindrical, about four times as long as wide, distally widening, dorsal margin with stiff setae; ultimate article slender, unarmed distally, with long setae (Fig. 1 d). Male minor cheliped with short ischium, its ventral margin furnished with small stout spiniform setae; merus broad, subtriangular in cross-section; ventrolateral margin smooth, unarmed; ventromesial margin straight, furnished with small spiniform setae, and ending in sharp distomesial tooth; dorsal margin ending bluntly distally; carpus rounded, cup-shaped; chela strongly compressed, with sculpture on distal portion of palm typical of A. macrocheles group: lateral face of palm with low crest starting at about 3 / 5 length of chela and ending in a sharp distolateral tooth; ventral margin with deep notch continuing as shallow depression on lateral side but barely noticeable on mesial surface; dorsal margin with short subcylindrical elevation distally with adhesive disk; mesial margin with crest ending in stout sharp tooth; linea impressa poorly marked; fingers slightly longer than palm; pollex with excavated cutting edge; dactylus flattened, lamellar, twisted laterally, strongly convex dorsally (Fig. 2 a, b). Female minor cheliped generally similar to male minor cheliped.
Male major cheliped with ischium short, furnished with small stout spiniform setae on ventromesial surface; merus stout, subtriangular in cross-section; ventrolateral margin smooth, unarmed; ventromesial margin straight, furnished with numerous small spiniform setae, and ending in stout, sharp distomesial tooth; dorsal margin ending bluntly distally; carpus very short, cup-shaped; chela compressed, with sculpture typical of A. macrocheles group; lateral face of palm with low crest starting at about 3 / 5 length of chela and ending in sharp distolateral tooth; ventral margin with deep notch continuing as shallow depression on lateral side and as shallow groove on mesial side; dorsal margin with subcylindrical elevation bearing adhesive disk distally; mesial margin with transversally interrupted crest ending in sharp tooth, latter overhanging propodo-dactylar articulation; linea impressa poorly marked; ventral surface with blunt setiferous tubercles; pollex short, somewhat twisted laterally, cutting edge with minute tooth followed by small notch; dactylus flattened, strongly turned laterally, convex dorsally; plunger reduced (Fig. 2 c–e). Female major cheliped slightly smaller than male major cheliped, but generally similar in shape and proportions.
Second pereiopod elongate, slender; ischium subequal to or slightly longer than merus; carpus with five articles with ratio approximately equal to 5–6: 3: 1.5: 1.5: 2; chela simple, fingers with tufts of setae (Fig. 1 e, n). Third pereiopod slender, with ischium bearing small ventrolateral spine; merus long, 11–12 times as long as wide, compressed, ventral margin unarmed; carpus more slender than merus, about half as long as merus, compressed, ventral margin unarmed; propodus much longer than carpus, ventral margin with a row of several slender spiniform setae, most distal ones in pairs, in addition to a pair of distoventral spiniform setae; dactylus about 1 / 4 length of propodus, subconical, curved ventrally, with acute tip and with minute dent subdistally (Fig. 1 f, g). Fourth pereiopod generally similar to third; fifth pereiopod with setal brush on propodus.
First pleopod with small endopod furnished with setae. Male second pleopod with appendix masculina exceeding appendix interna, but not reaching distal margin of endopod, with numerous setae as illustrated (Fig. 1 h). Female second pleopod with appendix interna only. Uropod with protopod bearing large acute lateral tooth; sinuous diaeresis with blunt tooth adjacent to stout distolateral spiniform seta, and row of small spiniform setae on endopod (Fig. 1 i, j). Gill formula typical for Alpheus, including five pleurobranchs (above P 1 –5), one arthrobranch (Mxp 3), two epipods (Mxp 1–2), five masigobranchs (Mxp 3, P 1–4), and five setobranchs (P 1–5). Colour pattern. Body reddish-orange due to groups of reddish chromatophores on pale yellow background; chelipeds more yellow-orange; antennular and antennal flagella yellowish; walking legs yellowish with some red chromatophores (Fig. 3). Variation. The female paratype is very similar to the male holotype, except for the slightly shorter orbital teeth (cf. Fig. 1 a, l) and a somewhat different ratio of carpal articles in the second pereiopod, with the first article being about 1.5 times as long as the second in the male holotype, and almost twice as long in the female paratype (cf. Fig. 1 e, n). The major and minor chelipeds of the male and female are fairly similar, except for some minor discrepancies in the proportions.
Etymology
Etymology. The name (lentiginosus = freckled in Latin) refers to the reddish spots formed by groups of chromatophores. Ecology. The holotype of A. lentiginosus n. sp. was found in a sediment sample taken at the base of a colony of Lophelia pertusa (Linnaeus, 1758) (Scleractinia, Caryophylliidae) attached to carbonate rock at 434– 438 m. The general habitat was videotaped and can be described as soft sediments overlying carbonate rock with patch reefs comprised of L. pertusa, various octocorals, some with associated ophiuroids, and sea anemones; squat lobsters and various demersal fishes were also observed at this site. The paratype was collected near a tilefish burrow located in a low relief mud bank. The bottom adjacent to and above the burrow was carbonate rock, covered with mud and cobble; pencil urchins (Cidaridae) and anemones were common throughout the area.
Discussion
Remarks. The new species clearly belongs to the Alpheus macrocheles (Hailstone, 1835) group defined mainly by the shape of the major chela, usually with two sharply ending crests on the palm and a flattened, somewhat twisted dactylus; in addition, most species also have well-developed, acute orbital teeth (see Banner & Banner 1982; Kim & Abele 1988). This group is represented by 11 species in the Atlantic Ocean, seven of them in the western Atlantic and four in the eastern and central Atlantic. At least six Atlantic species have been collected at depths below 100 m (Crosnier & Forest 1966; Chace 1972; Christoffersen 1979).
Taxon Treatment
- Anker, Arthur; Nizinski, Martha; 2011: Description of a new deep-water species of Alpheus Fabricius, 1798 from the Gulf of Mexico (Crustacea, Decapoda, Alpheidae), Zootaxa 2925: 50-55. doi
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