Pseudathanas banneri ( Kazmi & Kazmi, 2010 ), 2023

Anker, Arthur, 2023, Alpheid shrimps of the genera Athanas Leach, 1814, Athanopsis Coutière, 1897 and Pseudathanas Bruce, 1983 of the coasts of the Arabian Peninsula (Malacostraca: Decapoda: Caridea), Zootaxa 5383 (2), pp. 179-215 : 209-211

Pseudathanas banneri ( Kazmi & Kazmi, 2010)

( Figs. 15 , 16 )

Alberta banneri Kazmi & Kazmi 2010: 234 , figs. 108, 109.

Material examined. 1 male (cl 6.7 mm), FLMNH UF 68864 , Oman, Muscat, Qurum Beach , 23°37’31.7”N / 58°28’45.8”E, intertidal sandflat, depth at low tide less than 0.2 m, suction pump, in burrow, leg. A. Anker, 30.01.2022 [fcn BOMAN-10262] ; 1 male (cl 5.5 mm), FLMNH UF 68865 , same collection data as for previous specimen [fcn BOMAN-10263] ; 1 female (cl 6.45 mm), same collection data as for previous specimen, same burrow [fcn BOMAN-10264, specimen not deposited, see below] .

Description. See Kazmi & Kazmi (2010) for description and illustrations (as Alberta banneri ); complementary figures of the chelipeds are provided in Fig. 15 (see also Fig. 16d, e ); colour pattern of the species is described and illustrated for the first time (see below and Fig. 16 ).

Colour pattern. Body translucent with yellow tinge; carapace and pleon covered by bright red chromatophores, many of them resembling dendritic cells or chromosomes, pale yellowish chromatophores, and sometimes also with larger opaque blotches of white or pale yellowish chromatophores dorsolaterally (on carapace) or dorsally (on pleon); telson with few red chromatophores proximally and large blotches of white or pale yellowish chromatophores; antennular and antennal peduncles and bases of flagella with similar red and pale yellow chromatophores, distal part of flagella translucent whitish; chelipeds with yellowish and red chromatophores on dorsolateral surface of ischium and merus, carpus and chela hyaline white; second to fifth pereiopods and pleopods translucent whitish; uropodal endopod evenly speckled with yellow and large red chromatophores; uropodal exopod with large colourless “window”, with red and yellow chromatophores along lateral margin and in distal third, posterior to diaeresis ( Fig. 16 ). Kazmi & Kazmi (2010) noted the colour of P. banneri (as A. banneri ) as “off white (when fresh)”, probably describing a post-mortem specimen.

Distribution. North-Western Indian Ocean: presently known only from two localities in the Arabian Sea: Karachi, Pakistan, and Muscat, Oman.

Ecology. The three Omani specimens of P. banneri were extracted from burrows of an unknown fossorial animal on a relatively exposed, intertidal sandflat, in front of a small, degraded mangrove area. The substrate was composed of fine sand, patchily mixed with coarser sand, shells, shell fragments and small rocks and coral debris. All burrows, in which P. banneri was found, were located in a 5–10 m wide runoff with brackish water streaming from the mangrove to the sea at low tide. The burrowing macrofauna included the mantis shrimp Bigelowina phalangium ( Fabricius, 1798) and the ghost shrimp Neocallichirus cf. calmani (Nobili, 1904) [identification requires confirmation], which are both known to host symbiotic alpheid shrimps ( Ďuriš & Anker 2014; Anker & Ashrafi 2019). The habitat and collection data for the holotype are unknown.

Remarks. The Omani material of Pseudathanas banneri originally contained three specimens, two males (fcn BOMAN-10262, BOMAN-10263) and one female (fcn BOMAN-10264), from the same locality, only a few kilometres away from the historical centre of Muscat. Unfortunately, the only female, which was selected for dissection and line drawings, was lost during transportation, along with some other important decapod material (see Anker & Benzoni 2023). For this reason, the decision was made to leave the remaining two male specimens (FLMNH UF 68864, 68865) of this very rare genus and species as intact as possible. The chelipeds of one of the two males were drawn in situ ( Fig. 15 ), whereas the detached left female cheliped (subsequently lost together with the body of the specimen) is illustrated by colour photographs ( Fig. 16d, e ).

Pseudathanas banneri can be easily separated from P. darwiniensis by (1) the dorsally completely covered eyes (vs. partly exposed in P. darwiniensis ); (2) the stylocerite reaching slightly beyond half-length of the second article of the antennular peduncle (vs. reaching to the end of this article in P. darwiniensis ); (3) the subsymmetrical and subequal chelipeds (vs. asymmetrical and unequal chelipeds in P. darwiniensis ); (4) the ventrolateral margin of the cheliped merus crenulated and bearing a more prominent, distally more pointed tooth (vs. margin smoother and with a broader and blunter tooth in P. darwiniensis ); and (5) the second pereiopod carpus with four subarticles (vs. five subarticles in P. darwiniensis ) ( Kazmi & Kazmi 2010: fig. 108; Bruce 1983: figs. 2, 4). The colour patterns of the two species appear to be similar, at least judging from the brief description of the colour pattern of P. darwiniensis provided by Bruce (1983).

Despite the fact that no symbiotic association was noted for the Australian species, P. darwiniensis , by Bruce (1983), or for the holotype of P. banneri by Kazmi & Kazmi (2010), both currently known species of Pseudathanas appear to be infaunal, commensal shrimps.This hypothesis is supported by the general morphology of P. darwiniensis and P. banneri , as well as by the collection method (suction or “yabby” pump) of the Omani specimens.

Figures

FIGURE 15. Pseudathanas banneri (Kazmi & Kazmi, 2010) comb. nov., male (cl 6.7 mm) from Muscat, Oman (FLMNH UF 68864); a, right cheliped (drawn in situ), lateral; b, same, carpus and chela, mesial; c, left cheliped, distal portion of ischium, merus and carpus (drawn in situ), lateral.

FIGURE 16. Pseudathanas banneri (Kazmi & Kazmi, 2010) comb. nov., male (cl 6.7 mm) from Muscat, Oman (FLMNH UF 68864) [a, b]; female (cl 6.45 mm) from the same locality (not deposited, see text) [c–e]; a, shrimp in life (male), lateral (left side); b, same, dorsal; c, shrimp in life (female), frontal region, dorsal; d, e, left cheliped, lateral (d) and mesial (e). Photographs by the author.