Athanas daviei n. sp.

(Figs 3, 4, 8 E, F)

Type material. Holotype: male (CL 4.2 mm), QM W29047, Australia, Queensland, Great Barrier Reef, Lizard Island, Watson’s Bay, 14°39’50.4”S, 145°27’46.8”E, moderately high-energy sand flat, depth 1 m, suction (yabby) pump, from burrow, coll. A. Anker, 20 February 2009, fcn AUST-1377.

Description. Small-sized alpheid shrimp. Carapace distinctly elongate, slender, glabrous (Fig. 3 C). Rostrum straight, subtriangular in dorsal view, about 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. 3 A, B). Extracorneal teeth reduced to small, blunt, triangular protrusions; infracorneal and supracorneal teeth absent (Fig. 3 B, C). Pterygostomial angle broadly rounded; cardiac notch deep (Fig. 3 B, D).

Pleura of first four abdominal somites rounded posteroventrally; fifth pleuron with more pronounced posteroventral angle; sixth somite with large articulated subrectangular flap (Fig. 3 H). Telson widest at proximal third, distally tapering; dorsal surface with two pairs of strong spiniform setae located in deep pits, situated at some distance from lateral margin, at about 0.3 and 0.6 telson length, respectively; posterior margin broadly rounded, with two pairs of spiniform setae at each lateral angle, mesial being about twice times as long as lateral; margin between mesial spiniform setae furnished with long plumose setae (Fig. 3 J, K).

Eyes partly concealed in dorsal view, mostly visible in lateral view; cornea large, well pigmented, occupying most of terminal portion of eyestalk (Fig. 3 A, B).

Antennular peduncle fairly stout, with second article about as long as wide; first article with stylocerite reaching to 0.3 length of second article, with acute tip (Fig. 3 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. 3 B). Antenna with stout basicerite bearing large subacute distoventral tooth; scaphocerite not reaching end of antennular peduncle, ovate; blade broad, with convex anterior margin reaching slightly beyond moderately developed distolateral tooth; carpocerite slightly exceeding scaphocerite (Fig. 3 A, B).

Mouthparts typical for genus (in external view). Third maxilliped with coxa bearing conspicuously 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. 3 E, F).

Chelipeds subequal in size, asymmetrical in shape, both enlarged and carried folded (Fig. 4 A, D); ischium not particularly elongate, around three times as long as wide, with smooth margins, with row of slender spiniform setae along dorsal margin, most-distal longest, and one spiniform seta near distomesial margin; merus long, slightly widening distally, ventral surface depressed, especially distally, ventrolateral and ventromesial margins smooth; carpus very short, cup-shaped (Fig. 4 A, B); chela somewhat compressed, flattened on mesial (extensor) surface; ventrolateral (flexor) surface with row of six small tubercles (Fig. 4 A, C); fingers about 0.5 palm length, slightly twisted, curved ventrally; cutting edges serrated, with at least 12 small subtriangular teeth (Fig. 4 C). Minor cheliped only slightly smaller than major cheliped; ischium with more spiniform setae on distal margin, ventrolateral margin projecting distally; merus and carpus similar to those of major cheliped; chela with less tubercles on ventrolateral (flexor) surface; fingers distinctly longer compared to those of major cheliped, almost as long as palm, with similarly serrated cutting edges (Fig. 4 D, E).

Second pereiopod with ischium shorter than merus, both unarmed; carpus with five articles, first longest, about as long as four other articles combined, ratio of carpal articles (from proximal to distal) approximately equal to: 5.5: 1: 1: 1: 2.5; chela simple, distinctly longer than most-distal carpal article (Fig. 4 F). Third pereiopod stout, with distinctly compressed ischium, merus, carpus and propodus; ischium with two spiniform setae ventrolaterally; merus about 4.5 times as long as wide, unarmed, ventral and dorsal margin slightly convex; carpus much more slender than merus, about 0.4 merus length, with small spiniform seta distoventrally; propodus with two small spiniform setae along ventral margin and one distal spiniform seta adjacent to dactylus; dactylus about 0.4 propodus length, simple, relatively slender, gradually curving distally, bearing a few setae on dorsal margin (Fig. 4 G, H). Fourth pereiopod very similar to third pereiopod. Fifth pereiopod somewhat shorter and more slender than third or fourth pereiopods; ischium with one spiniform seta; propodus with two minute spiniform setae along ventral margin and three rows of thick serrulate setae distolaterally, most-distal row with longest setae (Fig. 4 I).

Male second pleopod with appendix masculina slightly exceeding appendix interna, apex with at least five stiff setae (Fig. 3 G). Uropod with lateral lobe of protopod bearing two small subacute teeth, latter situated close to each other; diaeresis straight except for the most mesial portion, latter being abruptly curved anteriorly; distolateral tooth blunt, adjacent spiniform seta moderately robust, relatively short (Fig. 3 I).

Gill-exopod formula typical for genus (see Anker & Jeng 2007); rudimentary exopod visible on basis of P1 (Fig. 4 B).

Colour pattern. Most of the body covered with rounded blotches of red chromatophores; dorsal surface of carapace and abdomen with patches of white chromatophores connected by narrow white band, and together forming a continuous white mediodorsal band (except on most posterior abdominal somites); uropods, telson, antennular and antennal peduncles covered with red chromatophores; antennular and antennal flagella colourless; major cheliped hyaline-white; walking legs mostly semi-transparent (Fig. 8 E, F).

Etymology. Named after Dr. Peter Davie (Queensland Museum, Brisbane), for his numerous contributions to the taxonomy of Brachyura and other decapods.

Habitat. Relatively exposed, moderately high-energy sand flat, at depth of about 1 m; 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. Athanas daviei n. sp. shares a number of characters with A. shawnsmithi n. sp. (see above), such as the absence of infracorneal and supracorneal teeth and smooth, non-dentate cheliped merus. However, A. daviei n. sp. may be separated from A. shawnsmithi n. sp. by the much shorter, proximally broader rostrum (cf. Figs. 1 A, 3A); the more completely covered eyes (cf. Figs. 1 A, 3A); the distinctly more elongate carapace (cf. Figs. 1 C, 3D); the non-projecting, blunt extracorneal teeth (vs. sharply projecting in A. shawnsmithi n. sp., cf. Fig. 1 B, 3B); the slightly shorter stylocerite (cf. Figs. 1 A, 3A); the quadrangular articulated plate on the sixth abdominal somite (vs. triangular in A. shawnsmithi n. sp., cf. Figs. 1 F, 3H); the presence of a row of spiniform setae on the distal margin of cheliped ischium (absent in A. shawnsmithi n. sp., cf. Figs. 2 A, E, 4B, D); the absence of setal brush on the lateral face of the cheliped fingers (present in A. shawnsmithi n. sp., cf. Figs. 2 A, 4B); the much shorter cheliped carpus (cf. Figs. 2 B, 4B); and several other features on the chelipeds and elsewhere (cf. Figs. 1–4). In addition, A. daviei n. sp. differs from A. shawnsmithi n. sp. in the colour pattern, for instance, in the uniform red tail fan (Fig. 8 F), which is conspicuously white-tipped in A. shawnsmithi n. sp. (Fig. 8 B, D), and in the hyaline-white major cheliped (Fig. 8 E), which is red-speckled in A. shawnsmithi n. sp. (Fig. 8 A, C).

Athanas daviei n. sp. may be separated from A. iranicus, which has a very similar frontal margin of the carapace, by the longer rostrum (cf. Fig. 4 A and Anker et al. 2010: fig. 2B); the quadrangular articulated plate on the sixth abdominal somite (vs. triangular in A. iranicus, cf. Fig. 3 H and Anker et al., 2010: fig. 2D); the lateral lobe of the uropodal protopod with two adjacent teeth (vs. with well-separated teeth in A. iranicus, cf. Fig. 3 I and Anker et al. 2010: fig. 2D); the shape of the major and minor chelae (cf. Fig. 4 A–E and Anker et al. 2010: fig. 3); and from A. squillophilus by the same criteria as A. shawnsmithi n. sp. (see above).

Athanas daviei n. sp. does not seem to be closely related to any other species of Athanas and can be distinguished from all previously reported Australian species by the same criteria as A. shawnsmithi n. sp. (see above).