Athanopsis platyrhynchus Coutiere 1897
Creators: name: Anker, Arthur
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Alpheidae
Athanopsis
Athanopsis platyrhynchus

description: Athanopsis platyrhynchus Coutière, 1897
Fig. 1
Athanopsis platyrhynchus Coutière 1897: 301; Coutière 1899: 69, 70, 141, 142, 176, 178 etc., figs. 17, 18, 135, 201, 211. (?) Not Athanopsis platyrhynchus — Miya 1984: 79, fig. 2.
Material examined. None (see above).
Description. (based on accounts in Coutière 1897, 1899) Small-sized alpheid shrimp (cl 4.25 mm). Carapace glabrous, not setose, not particularly swollen. Rostrum well developed, laterally compressed, subtriangular, longer than broad at base, with lateral margins convex proximally narrowing distally (fide Coutière 1899, fig. 17; see Fig. 1 A) or shallowly concave, narrowing distally (fide Coutière 1899, fig. 135; see Fig. 1 C) [see remarks below]; tip rounded in lateral view, subacute in dorsal view, almost reaching mid-length of second article of antennular peduncle; rostral carina rather slight, reaching level of eye base posteriorly (Fig. 1 A). Extracorneal teeth well developed, subtriangular, subacute distally (Fig. 1 A, B). Pterygostomial angle broadly rounded, slightly bluntly projecting anteriorly (Fig. 1 B).
Eyes almost completely concealed in dorsal view (their most-anterior portion remaining visible), partly visible in lateral view (Fig. 1 A, B), fully visible in frontal view.
Abdomen (described as similar to Athanas) with pleura of first to fourth somites rounded posteroventrally; sixth somite with triangular, articulated plate. Telson without anal tubercles; dorsal surface not described. Antennular peduncle stout; stylocerite blunt distally, reaching to mid-length of second article (fide Coutière 1899, fig. 135; see Fig. 1 C) [to distal third of second article fide Coutière 1897]; ventromesial carina with very strong, anteriorly produced tooth; second article as long as wide (Fig. 1 C); antennular flagella (described as similar to Athanas) with short accessory ramus on lateral flagellum. Antenna with carpocerite reaching beyond antennular peduncle by length of latter’s third article; scaphocerite broad, ovate, with small, obtuse distolateral tooth (Fig. 1 C).
Mouthparts and third maxilliped not described.
Chelipeds very asymmetrical in shape and unequal in size; carried folded when not in use (Fig. 1 D, E). Major cheliped (described as similar to Athanas djiboutensis Coutière, 1896) greatly enlarged, robust; ischium short, stout, merus long, swollen, widening distally, ventrally deeply excavated, ventrolateral and ventromesial margins smooth; carpus short, cup-shaped, chela swollen, pyriform; palm smooth, without tubercles, with low longitudinal ridge ventrally (probably marking depression on ventrolateral surface); fingers about 0.3 palm length, curved, gaping, dense setal brushes absent (or at least not illustrated); cutting edges of pollex and dactylus armed with large rounded teeth as illustrated (Fig. 1 D). Minor cheliped much smaller than major cheliped; ischium short; merus about three times as long as wide, widening distally, depressed ventrally; carpus vase-shaped; chela simple, with smooth, subcylindrical palm; fingers slender, simple, shorter than palm (Fig. 1 E).
Second pereiopod with carpus composed of five articles, first article subequal in length to sum of remaining four articles. Third and fourth pereiopods with stout (“ovate and swollen”) merus; propodus with four or five spiniform setae on ventral margin; dactylus simple, conical. Fifth pereiopod with reduced propodal brush, composed of two rows of stiff setae.
Pleopods and uropods not described.
Gill-exopod formula: 5 pleurobranchs, 0 arthrobranch, 6 epipods (Mxp1-3, P1-3), 4 setobranchs (P1-4), 3 exopods (Mxp1–3).
Colour pattern. Carapace and abdomen with pale diffuse red-orange transversal bands; chelipeds with more irregular patches of red-orange chromatophores (Coutière 1897, 1899).
Ecology. Lower intertidal with compact coral rock substrate mixed with coral debris and algal fragments, at the base of large hermatypic corals; both specimens were found under large coral rock deeply embedded in coral sand (Coutière 1899); a symbiotic association was not noted.
Type locality. Djibouti.
Distribution. Presently known only from the type locality in the Gulf of Aden (see map in Fig. 8).
Remarks. Coutière’s (1899) drawings of the rostrum of A. platyrhynchus appear to be somewhat inconsistent. In his fig. 17, the lateral margins of the rostrum are shown as slightly convex proximally (Fig. 1 A), but in fig. 135, they appear to be rather concave proximally (Fig. 1 C). It is not clear from the text (Coutière 1897, 1899), which of the above configurations is the correct one. Coutière’s description is also missing some important details, such as the armature of the third, fourth, and fifth pereiopods, and of the cheliped ischia.
Miya (1984) recorded A. platyrhynchus from Pohnpei (formerly Ponape, Caroline Islands Group), based on a single juvenile female specimen. However, in the shape of the rostrum and the width of the second article of the antennular peduncle, the Pohnpei specimen is more similar to A. brevirostris (see below). Thus, the identity of this specimen remains to be confirmed.
description: Published as part of Anker, Arthur, 2012, Notes on the Indo-West Pacific shrimp genus Athanopsis Coutière, 1897 (Crustacea, Decapoda, Alpheidae), with the description of a new species associated with echiurans (Annelida, Thalassematidae), pp. 48-61 in Zootaxa 3307 on pages 49-51, DOI: 10.5281/zenodo.215146