Axianassa canalis Kensley & Heard , 1990

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 : 104-105

Axianassa canalis Kensley & Heard, 1990

( Fig. 3–5 )

Axianassa canalis Kensley & Heard 1990 : 567, fig. 7.

Material examined. 1 male (cl 7.1 mm), MZUSP 34079, Pacific coast of Panama, Azuero Peninsula, Playa El Agallito, intertidal sand-mud flat, in burrow with pinnotherid crab and alpheid shrimp ( Leptalpheus sp.), coll. A. Anker, J.F. Lazarus, T. Kaji, 22.iii.2015; 1 male (cl 9.4 mm), MZUSP 34080, Pacific coast of Panama, El Agallito, intertidal, sand-mud flat, in burrow with pinnotherid crab, coll. A. Anker, J.F. Lazarus, T. Kaji, 22.iii.2015; 5 males (cl 5.1–13.5 mm), 5 females (cl 7.2–12.5 mm), MZUSP 34085, Pacific coast of Panama, Playa El Agallito, intertidal sand-mud flat, in burrows, coll. A. Anker, J.F. Lazarus, T. Kaji, 22.iii.2015; 1 male (cl 7.1 mm), UP, same collection data as for previous specimens; 1 male (cl 5.5 mm), MZUSP 34092, Pacific coast of Panama, Las Perlas Archipelago, Isla Casayeta, large bay with mud flat fringed by rocks and mangroves, 0.3 m, in burrows, coll. A. Anker, 20.iv.2015.

Description. See Kensley & Heard (1990); additional illustrations and colour photographs are provided in Figs. 3–5 .

Colouration. Creamy whitish, with faint straw or pale yellow tinge; inner organs yellowish ( Fig. 5 ).

Distribution. Eastern Pacific: currently known only from Panama ( Panama Canal, Azuero Peninsula, Las Perlas Archipelago) ( Kensley & Heard 1990; present study).

Ecology. Lower intertidal and shallow subtidal (present material: less than 0.5 m) mud flats, often near mangroves; in burrows in mud or muddy sand; sometimes with commensal pea crabs (D.L. Felder, in study) and/or alpheid shrimps, Leptalpheus sp. (A. Anker, in study).

Remarks. Axianassa canalis was previously known based on an incomplete male holotype specimen, missing both chelipeds, collected “from dredge flume” at the Pacific entrance of the Panama Canal ( Kensley & Heard 1990). The present material of A. canalis consists of a dozen mostly complete and adult specimens of both sexes collected near Playa El Agallito, on the eastern coast of the Azuero Peninsula, and one relatively young individual collected in a muddy bay of Isla Casayeta, Las Perlas Archipelago. The previously unknown major and minor chelipeds ( Fig. 4 ) are characterised by the presence of three or four strong teeth on the ventrolateral margin of the ischium and one very stout sharp tooth on the ventromesial margin of the merus, at about mid-length of this article. The cheliped carpus is smooth and unarmed ventrally, whereas the ventral margin of the palm is rugose, more so on the major chela ( Fig. 4 A, C). In both the major and the minor chelipeds, the distomesial and distolateral margins of the palm are armed with several strong teeth adjacent to the articulation with the dactylus ( Fig. 4 ). The cutting edges of the major cheliped fingers are armed with very stout teeth proximally and smaller serrations more distally; the dactylus may also have a large hiatus in proximal half or near mid-length ( Fig. 4 A, B). The cutting edge of the minor cheliped pollex is armed with two or three large sharp teeth in addition to serrations; the dactylus has serrations only ( Fig. 4 C, D). The distolateral margin of the uropodal exopod usually bears one distolateral tooth ( Fig. 3 D), rarely two teeth. The first pleuron is ventrally armed with a strong process in both sexes. The most important diagnostic character of A. canalis is the presence of a dense field of thick fusiform setae on the ventral margin of the third maxilliped ischium ( Fig. 3 B; see also Kensley & Heard 1990: fig. 7D).

Figures

FIGURE 3. Axianassa canalis Kensley & Heard, 1990: male (cl 7.1 mm) from Azuero Peninsula, Panama (MZUSP 34079); A—frontal region, dorsal view; B—third maxilliped, lateral view [arthrobranch and epipod omitted]; C—same, detail of crista dentata, dorsomesial view; D—uropod, dorsal view.

FIGURE 4. Axianassa canalis Kensley & Heard, 1990: male (cl 7.1 mm) from Azuero Peninsula, Panama (MZUSP 34079); A—left (major) cheliped, lateral view; B—same, chela, mesial view; C—right (minor) cheliped, lateral view; D—same, chela, mesial view.

FIGURE 5. Axianassa canalis Kensley & Heard, 1990: A, B—male (cl 7.8 mm) from Azuero Peninsula, Panama (MZUSP 34085), in dorsal (A) and lateral (B) views; C—male (cl 9.4 mm) from the same locality (MZUSP 34080), in lateral view.