Athanas shawnsmithi Anker, 2011, n. sp.
Creators: name: Anker, Arthur
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Alpheidae
Athanas
Athanas shawnsmithi

description: Athanas shawnsmithi n. sp.
(Figs 1, 2, 8 A–D)
Type material. Holotype: ovigerous female (CL 5.2 mm), QM W29045, Australia, Queensland, Great Barrier Reef, Lizard Island, about 50 m east of Lumus Beach (in front of marine station), 14°40’92.6”S, 145°26’95.2”E, patches of silt and sand near large rocks, depth less than 0.5 m, suction (yabby) pump, from burrow, coll. A. Anker, 12 February 2009, fcn AUST-0700. Allotype: male (CL 4.1 mm), QM W29046, same collection data as for holotype, from the same burrow (mates), fcn AUST-0699.
Description. Small-sized alpheid shrimp. Carapace somewhat elongate, glabrous (Fig. 1 C). Rostrum slightly descendant, about twice as long as broad at base; lateral margins slightly concave proximally; tip acute, reaching to distal margin of first article of antennular peduncle; rostral carina not distinct (Fig. 1 A, B). Extracorneal teeth triangular, sharp, not reaching anterior margin of cornea; infracorneal and supracorneal teeth absent (Fig. 1 B). Pterygostomial angle broadly rounded; cardiac notch deep (Fig. 1 B, C).
Pleura of first four abdominal somites rounded posteroventrally; fifth pleuron with more pronounced posteroventral angle; sixth somite with large articulated subtriangular flap (Fig. 1 F). Telson widest at proximal third, distally tapering; dorsal surface with two pairs of very strong spiniform setae located in deep pits, situated at some distance from lateral margin, at about 0.5 and 0.7 telson length, respectively; posterior margin broadly rounded, with two pairs of spiniform setae at each lateral angle, mesial being almost three times as long as lateral; margin between mesial spiniform setae furnished with numerous long plumose setae (Fig. 1 H, I).
Eyes completely exposed in dorsal and lateral views; cornea large, well pigmented, occupying most of terminal portion of eyestalk (Fig. 1 A, B).
Antennular peduncle moderately stout, with second article slightly longer than wide; first article with stylocerite reaching to about 0.5–0.6 length of second article, with acute tip (Fig. 1 A); ventromesial carina with anteriorly directed tooth; lateral flagellum biramous, fused portion composed of three articles; accessory ramus composed of at least three non-discernable articles each bearing a tuft of aesthetascs (Fig. 1 B). Antenna with stout basicerite bearing sharp distoventral tooth; scaphocerite not reaching beyond end of antennular peduncle, ovate; blade broad, with convex anterior margin not reaching beyond strong distolateral tooth; carpocerite slightly exceeding scaphocerite (Fig. 1 A, B).
Mouthparts typical for genus (in external view). Third maxilliped with coxa bearing slightly produced, distally subacute lateral plate above mastigobranch; antepenultimate article rather stout, somewhat flattened; penultimate article about 2.5 times as long as wide proximally; ultimate article furnished with transverse rows of thick serrulate setae, tapering distally, tip with two slender spiniform setae; arthrobranch absent (Fig. 1 D).
Chelipeds of female unequal in size, asymmetrical in shape; only one cheliped present in male, being very similar to major cheliped of female (Fig. 2 A–D); major cheliped enlarged, robust, carried folded; ischium moderately long, around three times as long as wide, with smooth margins, without spiniform setae on dorsal margin; one minute spiniform seta present on distomesial surface; merus long, abruptly widening in distal third, ventral surface excavated, especially distally, ventrolateral and ventromesial margins smooth; carpus cup-shaped, distally broadening, with low bump dorsally; chela somewhat compressed, slightly flattened on mesial (extensor) surface; ventrolateral (flexor) surface with row of three small tubercles (Fig. 2 A, B); fingers about 0.3 palm length, somewhat twisted and curved ventrally (Fig. 2 C); pollex with dense setae on lateral (flexor) surface; cutting edges with teeth gradually becoming broader and lower distally (Fig. 2 D). Female minor cheliped with ischium unarmed; merus elongate, about six times greatest width, depressed ventrally; carpus cylindrical, widening distally, about 0.7 length of merus; chela about as long as merus, simple, with fingers slightly shorter than palm (Fig. 2 E).
Second pereiopod with ischium shorter than merus, both unarmed; carpus with five articles, first longest, slightly longer than sum of four other articles, ratio of carpal articles (from proximal to distal) approximately equal to: 5: 1: 1: 1: 2; chela simple, slightly longer than most-distal carpal article (Fig. 2 F). Third pereiopod stout, with distinctly compressed ischium, merus, carpus and propodus; ischium with two spiniform setae ventrolaterally; merus slightly more than four times as long as wide, unarmed; carpus more slender than merus, about 0.4 merus length, with small spiniform seta distoventrally; propodus with three slender spiniform setae along ventral margin and one stouter distal spiniform seta adjacent to dactylus; dactylus about 0.4 propodus length, simple, slender, gradually curving distally, bearing a few setae on dorsal margin (Fig. 2 G, H). Fourth pereiopod very similar to third pereiopod. Fifth pereiopod shorter and more slender than third or fourth pereiopods; ischium with one spiniform seta; propodus with three small spiniform setae along ventral margin and three rows of thick serrulate setae distolaterally, most-distal row with longest setae (Fig. 2 I).
Male second pleopod with appendix masculina greatly exceeding appendix interna, apex with at least four stiff setae (Fig. 1 E). Uropod with lateral lobe of protopod bearing two small subacute teeth, latter situated at some distance from each other; diaeresis straight except for the most mesial portion, latter being abruptly curved anteriorly; distolateral tooth blunt, adjacent spiniform seta moderately robust and long (Fig. 1 G).
Gill-exopod formula typical for genus (see Anker & Jeng 2007); no rudimentary exopod visible on basis of P1. Colour pattern. Most of the body covered with rounded blotches of red chromatophores; dorsal surface of carapace and abdomen with large patches of white chromatophores forming disrupted mediodorsal band; distal half of uropod and telson conspicuously white; antennular and antennal peduncles with dense areas of red chromatophores; flagella colourless; major cheliped speckled with large patches of red chromatophores, chela fingers whitish; walking legs mostly semi-transparent with some red chromatophores (Fig. 8 A–D); eggs olivegreen (Fig. 8 C).
Etymology. Named after Shawn Smith (Australian Institute of Marine Science, Townsville, Australia), for the impeccable logistic organisation of CReefs trips and assistance in the field.
Habitat. Near-shore patches of silty sand, next to large rocks; associated with unknown burrowing hosts, possibly Callianassidae.
Type locality. Lizard Island, Great Barrier Reef off Queensland, Australia.
Distribution. Presently known only from the type locality.
Remarks. The most important features of Athanas shawnsmithi n. sp. are the presence of acute extracorneal teeth; the absence of infracorneal and supracorneal teeth; the chelipeds unequal and asymmetrical (at least in females), and carried folded; the major cheliped with merus having smooth margins, and with fingers distinctly twisted and furnished with setal brush on lateral (flexor) margin; and the third to fifth pereiopods stout, not particularly slender, with simple, moderately slender, but not extremely elongate dactylus. This combination of characters occurs only two other species of Athanas, A. iranicus Anker, Naderloo & Marin, 2010 from Iran and A. squillophilus Hayashi, 2002 from Japan. Athanas shawnsmithi n. sp. differs from A. iranicus by the much longer rostrum (cf. Fig. 1 A and Anker et al. 2010: fig. 2B); the absence of dense setal brushes on the lateral face of the palm and carpus, and rows of stout spiniform setae on the ischium and proximal portion of the merus (cf. Fig. 2 A and Anker et al. 2010: fig. 3A, B); and the presence of two spiniform setae on the ischium of the third pereiopod vs. only one seta in A. iranicus (cf. Fig. 2 G and Anker et al. 2010: fig. 4B). Athanas shawnsmithi n. sp. is also distinguishable from A. squillophilus, for instance, in the rounded pterygostomial angle, which is sharply projecting in A. squillophilus (cf. Fig. 1 B and Hayashi 2002: fig. 1); the setal brushes not extending from the fingers to the palm, as they do in A. squillophilus (cf. Fig. 2 A and Hayashi 2002: fig. 3A, B); and the shorter, cupshaped cheliped carpus, which is longer and more vase-shaped in A. squillophilus (cf. Fig. 2 A and Hayashi 2002: fig. 3A).
None of the other 10 species currently known from Australia (Banner & Banner 1973; Anker & Ahyong 2007a) appears to be closely related to A. shawnsmithi n. sp. Each of them may be separated from the new species by several, usually very obvious features. For instance, A. areteformis Coutière, 1903 and A. djiboutensis Coutière, 1897 differ from the new species by the presence of sharp supracorneal teeth; A. granti Coutière, 1908 and A. areteformis and by the general shape of the chelipeds, carried extended; A. ornithorhynchus Banner & Banner, 1973, A. parvus de Man, 1910 and A. granti by the biunguiculate dactylus of the third to fifth pereiopods; A. ornitorhynchus by the duck-bill shaped minor chela; A. japonicus Kubo, 1936 and A. parvus by the presence of sharp infracorneal teeth; A. japonicus and A. sydneyensis Anker & Ahyong, 2007 by the toothed cheliped merus and distinctly more slender third to fifth pereiopods; A. locincertus Banner & Banner, 1973 by the presence of small infracorneal teeth; the presence of strong spiniform setae on the cheliped ischium; and the more numerous spiniform setae on the third pereiopod; A. dimorphus Ortmann, 1894 and A. haswelli Coutière, 1908 by the presence of infracorneal teeth and symmetrical, non-enlarged chelipeds in females.
description: Published as part of Anker, Arthur, 2011, Four new infaunal decapod crustaceans (Caridea: Alpheidae and Gebiidea: Axianassidae) from Lizard Island, Australia, one of them also occurring in Moorea, French Polynesia, pp. 1-22 in Zootaxa 2734 on pages 2-5, DOI: 10.5281/zenodo.202972