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

description: Athanopsis saurus n. sp.
(Figs 5–7, 8 G, H)
Type material. Holotype: male (CL 4.0 mm), QM W29048, Australia, Queensland, Great Barrier Reef, Lizard Island, Casuarina Beach near marine station, 14°40’31.4”S, 145°26’39.5”E, sand flat with corals and coral rubble, depth 1 m, suction (yabby) pump, from burrow, coll. A. Anker, 24 February 2009, fcn AUST-1723.
Description. Small-sized alpheid shrimp. Body somewhat elongate, slender. Carapace glabrous, not setose. Rostrum well developed, laterally compressed, straight, slightly longer than broad at base, lateral margins distinctly convex in proximal half, straight in distal half; tip rounded in lateral view, subacute in dorsal view, reaching 0.4 length of second article of antennular peduncle; rostral carina distinct, not reaching level of eye base posteriorly (Fig. 5 A, B). Extracorneal teeth well developed, subtriangular, blunt distally, reaching to or slightly beyond anterior margin of cornea (Fig. 5 A, B). Pterygostomial angle slightly protruding, blunt; cardiac notch deep (Fig. 5 B).
Pleura of first to fourth abdominal somites rounded posteroventrally; fifth pleuron with subacute posteroventral angle; sixth somite with large articulated triangular flap. Telson widest at proximal third, distally tapering; dorsal surface with two pairs of minute spiniform setae, 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 slender spiniform setae at each lateral angle, mesial almost three times as long as lateral; mesial spiniform setae obscured by long plumose setae originating from median area of posterior margin, between mesial spiniform setae (Fig. 5 I, J).
Eyes partly exposed in dorsal and lateral views; cornea large, well pigmented, occupying most of terminal portion of eyestalk (Fig. 5 A, B).
Antennular peduncle stout, with second article slightly shorter than wide; stylocerite subacute distally, reaching to 0.5 length of third article (Fig. 5 A); ventromesial carina with very strong, anteriorly produced tooth; lateral flagellum biramous, fused portion composed of three articles; accessory ramus composed of at least five barely discernable articles each bearing a tuft of aesthetascs (Fig. 5 B). Antenna with basicerite stout, bearing large subacute tooth distoventrally (tip broken on the right side in the holotype); scaphocerite slightly not or only slightly exceeding end of antennular peduncle, ovate; blade very broad, with slightly convex anterior margin not exceeding strong distolateral tooth; carpocerite about the same length as scaphocerite (Fig. 5 A, B).
Mouthparts not dissected, appearing typical for genus in external view. Third maxilliped with coxa bearing distally subacute lateral plate above mastigobranch; antepenultimate article flattened, somewhat broadened distally; penultimate article about twice as long as wide proximally; ultimate article furnished with transverse rows of thick serrulate setae, tapering distally, tip with at least three stout spiniform setae (Fig. 5 D, E).
Chelipeds very asymmetrical in shape and unequal in size; carried folded (Fig. 6 A, D). Major cheliped greatly enlarged, robust; ischium stout, with three spiniform setae on dorsal margin, mesial side flattened; merus long, inflated, widening distally, ventrally deeply excavated, ventrolateral and ventromesial margins smooth; carpus short, cup-shaped, with large, blunt process ventromesially; chela deeply depressed on ventrolateral (flexor) surface, distolateral surface with one large tubercle; ventromesial surface with four small tubercles or transverse ridges; fingers about 0.4 palm length, twisted, curved, with dense setal brush on lateral (flexor) surface of pollex extending to adjacent portion of palm (Fig. 6 A, B); cutting edges of pollex and dactylus with large rounded teeth (Fig. 6 C). Minor cheliped about four times smaller than major cheliped in volume; ischium very short, with one spiniform seta on distodorsal margin; merus about three times as long as wide, depressed ventrally; carpus vaseshaped, smooth; chela simple, slender, with fingers about as long as palm, cutting edges unarmed except for minute isolated denticles (Fig. 6 D, E).
Second pereiopod with ischium much shorter than merus, both unarmed; carpus with five articles, first longest, longer than remaining four articles combined, ratio of carpal articles (from proximal to distal) approximately: 6: 1: 1.2: 1.2: 2.5; chela simple, slightly longer than most-distal carpal article, with fingers subequal to palm (Fig. 7 A). Third pereiopod stout, with strongly compressed ischium, merus, carpus and propodus; ischium with two spiniform setae on ventrolateral surface and one spiniform seta on distodorsal margin; merus about four times as long as wide, distolateral margin bearing subacute tooth; carpus more slender than merus, less than half-length of merus, with three stout spiniform setae on distoventral margin; propodus with five alternating spiniform setae along ventral margin and three longer distal spiniform setae surrounding base of dactylus; dactylus slightly less than half-length of propodus, simple, conical, gradually curving distally, dorsal margin slightly notched at about 0.7 dactylar length and furnished with some setae (Fig. 7 B, C). Fourth pereiopod generally similar to third pereiopod, more slender (Fig. 7 D). Fifth pereiopod much more slender than third or fourth pereiopods; ischium with one spiniform seta on ventrolateral surface; merus with subacute tooth on distolateral margin; carpus with two or three spiniform setae on distoventral margin; propodus with small spiniform setae along ventral margin and two robust spiniform setae on distomesial margin, close to dactylus; distolateral surface with three rows of thick serrulate setae, most-distal row bearing most and longest setae; dactylus similar to that of third pereiopod (Fig. 7 E, F).
Male second pleopod with appendix masculina slightly exceeding appendix interna, apex with at last six stiff setae (Fig. 5 F). Uropod with lateral lobe of protopod bearing larger acute tooth laterally and small subacute angle mesially; exopod with diaeresis straight, most mesial section deeply curving anteriorly; distolateral tooth subacute, adjacent distolateral spiniform seta very strong; posterior margin with row of stout spine-like setae above much longer flexible plumose setae (Fig. 5 G, H).
Gill-exopod formula typical for genus (see Miya 1980; Berggren 1991); no rudimentary exopod visible on basis of P1.
Colour pattern. Most of the carapace and tail fan and large portion of the abdomen (especially second, third and sixth somites) covered with white chromatophores; remaining areas semitransparent more or less intensely speckled with red chromatophores, most intensely near anterolateral margin of the carapace and on first and fourth abdominal somites; antennular peduncles covered with red chromatophores; most of antenna colourless; flagella colourless; cheliped hyaline-white; walking legs semitransparent (Fig. 8 G, H).
Etymology. Specific name derived from the Greek sauros (neo-Latin saurus) for “lizard”, in reference to Lizard Island, the type locality.
Habitat. Sand flat with large coral heads and coral rubble, at depth of about 1 m; associated with unknown burrowing hosts, possibly Callianassidae or Echiura (see Berggren 1991).
Type locality. Lizard Island, Great Barrier Reef off Queensland, Australia.
Distribution. Presently known only from the type locality.
Remarks. Athanopsis saurus n. sp. is closely related to the other five species of Athanopsis, being distinguishable from each of them by at least two morphological features. For example, A. saurus n. sp. differs from the type species, A. platyrhynchus Coutière, 1897 (Djibouti), by the distinctly longer stylocerite, reaching the mid-length of the third article of the antennular peduncle vs. reaching only mid-length of the second article in A. platyrhynchus; the somewhat shorter carpocerite, reaching only slightly beyond the scaphocerite blade vs. greatly overreaching the blade in A. platyrhynchus (cf. Fig. 5 A, B and Coutière 1899: fig. 135); and the presence of very conspicuous setal brushes on the lateral (flexor) surface of the major chela fingers and adjacent palm (cf. Fig. 6 A, B, not illustrated or mentioned by Coutière 1897, 1899). Athanopsis saurus n. sp. also differs from A. brevirostris Banner & Banner, 1981 (Red Sea) by the much longer, proximally convex rostrum and distinctly longer second article of the antennular peduncle (cf. Fig. 5 A and Banner & Banner 1981: fig. 5a); and from A. dentipes Miya, 1980 (Japan); A. rubricinctuta Berggren, 1991 (Mozambique) and A. australis Banner & Banner, 1982 (southern Australia) by the absence of spiniform setae on the meri of the third to fifth pereiopod and the presence of dense setal brushes on the major chela; from both A. dentipes and A. australis by the distinctly longer stylocerite; and specifically from A. rubricinctuta by the presence of orbital teeth (cf. Figs. 5–7 and figures in Miya 1980; Banner & Banner 1982; Berggren 1991; Anker & Ahyong 2007b).
In life, A. saurus n. sp. can be clearly separated from A. rubricinctuta, A. dentipes and A. australis by its diagnostic colour pattern (cf. Fig. 8 G, H; figures in Miya 1980 and Berggren 1991; colour photograph in Poore 2004). The colour pattern of A. platyrhynchus was described as “marqués de dendrites [= chromatophores] rouge orangé disposés en bandes transversales diffuses sur le thorax and l’abdomen, et irreguliérement sur les pinces” (Coutière 1899: 496), which seems to be different from the colour pattern of A. saurus n. sp. The previously unknown colour pattern of A. brevirostris is also different from the colour of A. saurus n. sp.; it will be described and illustrated elsewhere (Anker, unpubl.).
It must be noted that the accuracy of Coutière’s (1899) and Banner & Banner’s (1981, 1982) drawings is not always reliable. For instance, Coutière (1899) illustrated the frontal margin of A. platyrhynchus twice in his monograph, in Fig. 17 on p. 69 and in Fig. 135 on p. 141. Surprisingly, the two figures show a very differently shaped rostrum: in Fig. 17, its proximal lateral margin is more convex, approaching the condition found in A. saurus n. sp. or in A. australis, whereas in Fig. 135, it is more concave resembling more the condition seen in A. dentipes. Neither of the three possibilities, i.e., inaccurate drawings, intraspecific variation, or more than one species in Coutière’s material reported as A. platyrhynchus, can be excluded at this stage. Anker & Ahyong (2007b) pointed out to the inaccuracies in the description and illustration of A. australis by Banner & Banner (1982). Furthermore, the present author is aware of at least two important errors in Banner & Banner’s (1981) description and figures of A. brevirostris (C.H.J.M. Fransen, pers. comm.); a redescription of this species based on new material will be published elsewhere (Anker, in prep.).
Miya (1984) reported under the name A. platyrhynchus a very small and possibly immature female specimen (CL 1.4 mm) from Ponape, of which he provided some figures. This specimen differs from Coutière’s types from Djibouti in at least two features (length of the stylocerite and shape of the rostrum) and is therefore most likely not A. platyrhynchus sensu Coutière (1899); its true identity remains undetermined.
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 9-13, DOI: 10.5281/zenodo.202972