Axianassa darrylfelderi Anker & Lazarus, 2015

Anker, Arthur & Pachelle, Paulo P. G., 2016, Mud-shrimps of the genus Axianassa Schmitt, 1924 from Panama, with description of two new species (Decapoda: Gebiidea: Laomediidae), Zootaxa 4111 (2), pp. 101-125 : 109-110

Axianassa darrylfelderi Anker & Lazarus, 2015

( Fig. 7 )

Axianassa darrylfelderi Anker & Lazarus 2015: 116 , figs. 1–4.

Material examined. 1 male (cl 8.9 mm), MZUSP 34081, Pacific coast of Panama, Playa El Agallito, intertidal sand-mud flat, in burrow, coll. A. Anker, J.F. Lazarus, T. Kaji, 22.iii.2015; 1 ovigerous female (cl 9.0 mm), MZUSP 34489, Pacific coast of Panama, Playa El Agallito, intertidal sand-mud flat, in burrow together with alpheid shrimp ( Leptalpheus sp.), coll. A. Anker, J.F. Lazarus, T. Kaji, 22.iii.2015.

Description. See Anker & Lazarus (2015); additional colour photographs are provided in Fig. 7 .

Colouration. Pale pink to more intense reddish pink, depending on state of chromatophore contraction; inner organs yellow or orange ( Fig. 7 ; see also Anker & Lazarus 2015: figs. 3, 4).

Distribution. Eastern Pacific: Colombia (Bahía Málaga) and Panama (Playa El Agallito, Azuero Peninsula) ( Anker & Lazarus 2015; present study).

Ecology. Intertidal and shallow subtidal (less than 0.5 m) mud flats, sometimes near mangroves; in burrows in mud, sometimes with commensal alpheid shrimps, Leptalpheus sp. (A. Anker, in study).

Remarks. The recently described Axianassa darrylfelderi was previously only known from the type material from Bahía Málaga, Colombia ( Anker & Lazarus 2015). The two specimens collected on the eastern coastline of Panama’s Azuero Peninsula represent only the second record of A. darrylfelderi and also the first record of the species for Panama. They match the type material from Colombia in all diagnostic characters.

Anker & Lazarus (2015) used three characters to separate A. darrylfelderi from its presumed western Atlantic sister species, A. australis Rodrigues & Shimizu, 1992 , based on the description and illustrations provided by Rodrigues & Shimizu (1992). These characters are the presence or absence of teeth on the distolateral margin of the uropodal exopod (two or three in A. darrylfelderi vs. none in A. australis ), the length of the antennal acicle (relatively longer in A. darrylfelderi compared to A. australis ) and the armature of the cutting edges of the pollex in the male minor cheliped (with three strong double teeth, in addition to numerous smaller teeth in A. darrylfelderi vs. with one proximal double or triple tooth and two simple, more distal teeth in A. australis ).

A thorough examination of the Panamanian specimens of A. darrylfelderi revealed the presence of five (male) and one to three (female) teeth and a small movable spinule or spiniform seta (in both male and female), the latter obscured by the adjacent plumose setae, on the distolateral margin of the uropodal exopod. This observation prompted a re-examination of the male paratype from Colombia (MZUSP 33014), which was confirmed to have only one tooth and one spiniform seta, the latter having been either overlooked (being concealed by the adjacent thick plumose setae) or illustrated as a fixed tooth in Anker & Lazarus (2015: fig. 1K). Four Brazilian specimens of A. australis , viz. the male holotype from Bahia (MZUSP 10584), the male paratype from São Paulo (MZUSP 11105), a male from Ceará (MZUSP 32611), and an ovigerous female from Bahia (MZUSP 32131), were also examined. Each of them was found to have one to three fixed teeth and one spiniform seta on the uropodal exopod, which suggests that the description “rami without spines” and the illustration of the uropod of A. australis in Rodrigues & Shimizu (1992: p. 319, fig. 20) are incorrect. Thus, both species have at least one fixed tooth and a small spiniform seta on the distolateral margin of the uropodal exopod.

The antennal acicle was illustrated as relatively short, not reaching 0.25 length of the fourth article, in the original description of A. australis by Rodrigues & Shimizu (1992: fig. 3). Our examination of the holotype and two other Brazilian specimens of A. australis shows that the acicle tip indeed reaches at most to about 0.25 length of the fourth article, thus being somewhat shorter than the acicle of A. darrylfelderi , which is closer to 0.35 length of the fourth article ( Anker & Lazarus 2015). In contrast, the armature on the cutting edge of the pollex of the male minor cheliped does not seem to be a reliable character to separate A. darrylfelderi from A. australis , because two strong double teeth are present at least in one Brazilian specimen of the latter species (MZUSP 32611).

During our search for other morphological characters distinguishing A. darrylfelderi from A. australis , we noted that the former species is variable in the number of teeth on the dorsomesial surface of the third maxilliped coxa. Three specimens, viz. the ovigerous female from Panama (MZUSP 34489), as well as the holotype (cf. Anker & Lazarus 2015: fig. 1H, I) and paratype (MZUSP 33014) from Colombia have two small adjacent teeth, whereas one male from Panama (MZUSP 34081) has only one larger tooth, as in A. australis (cf. Rodrigues & Shimizu 1992: fig. 9). In males of A. darrylfelderi , the lateral surface of the third to fifth pleura is covered by a fine pubescence composed of numerous long setae ( Anker & Lazarus 2015: fig. 4A). In males of A. australis , this pubescence appears to be much denser, especially on the fourth and fifth pleura ( Rodrigues & Shimizu 1992: fig. 1), sometimes obscuring the pleural margins. The palm-finger height-length ratio of the male major cheliped appears to be higher in A. darrylfelderi than in A. australis , but this may only be true for very large males (cf. Anker & Lazarus 2015: fig. 2A, B; Rodrigues & Shimizu 1992: fig. 12). In summary, the extent of variation of the aforementioned characters cannot be evaluated based on the currently available material. Nevertheless three of them are tentatively included in the key below as morphological differences between these two geographically separated cryptic taxa. Molecular analyses, e.g., of the barcoding segment of COI, are highly desirable to confirm the validity of A. darrylfelderi .

Figures

FIGURE 7. Axianassa darrylfelderi Anker & Lazarus, 2015: A – C—male (cl 8.9 mm) from Azuero Peninsula, Panama (MZUSP 34081); A—dorsal view; B—detached major cheliped, mesial view; C—detached minor cheliped, mesial view; D, E—ovigerous female (cl 9.0 mm) from the same locality (MZUSP 34489), in dorsal (D) and lateral (E) views.