Mud-shrimps of the genus Axianassa Schmitt, 1924 from Panama, with description of two new species (Decapoda: Gebiidea: Laomediidae)
Author
Anker, Arthur
Author
Pachelle, Paulo P. G.
text
Zootaxa
2016
4111
2
101
125
journal article
39076
10.11646/zootaxa.4111.2.1
ee60b4f8-1cce-4e63-89e6-126b89d45e64
1175-5326
257706
0208587B-598C-4202-A4BA-8FDECD2C93B9
Axianassa mineri
Boone, 1931
(
Figs. 1
,
2
)
Axianassa mineri
Boone 1931
: 157
, fig. 10;
Hernández-Aguilera 1998
: 310
;
Kensley &
Heard
1990
: 563
, fig. 4;
Dworschak 2013
: 44
.
Material examined
.
1 male
(cl
8.9 mm
),
1 female
(cl
7.4 mm
),
MZUSP
34081, Pacific coast of
Panama
, Las Perlas Archipelago,
Isla
Contadora, Playa Larga, low tide, mid-intertidal, near water edge under rocks in muddy sand, coll. T. Kaji, A. Anker, A.R. Palmer,
17.iv.2015
;
1 male
(cl
3.1 mm
),
FLMNH
UF 39751,
Mexico
, Baja California Sur, Los Frailes, 23.3827–109.4253, intertidal, coll. T.A. Ebert, D.M. Dexter,
28.i.1972
.
Description
. See
Boone (1931)
and
Kensley &
Heard
(1990)
; additional illustrations and colour photographs are provided in
Figs. 1
,
2
.
Colouration
. Creamy whitish, with faint pale-yellow tinge; inner organs yellow-orange (
Fig. 2
).
Distribution
. Eastern Pacific:
Mexico
(Los Frailes, Baja California Sur; Islas Tres Marías and
Isla
Santa Isabel off Nayarit);
Costa Rica
(
Isla
del Coco);
Panama
(Las Perlas Archipelago) (
Boone 1931
;
Hernández-Aguilera 1998
;
Dworschak 2013
; present study).
Ecology.
Mid- to lower intertidal of offshore islands and drier continental shores; in shallow horizontal or oblique burrows made in muddy sand under rocks and larger pieces of coral rubble.
Remarks
.
Axianassa mineri
is a rather distinctive species of the genus, characterised by a broadly rounded frontal margin of the carapace, without a clear rostral projection (
Kensley &
Heard
1990: fig. 4D
); a very short antennal acicle bearing two distal teeth (
Fig. 1
A; see below); the presence of several rows of stout corneous spines throughout the full length of the dactylus of the third and fourth pereiopods (
Fig. 1
C); the third maxilliped carpus with a strong ventral tooth (
Kensley &
Heard
1990: fig. 4A
); and the presence of teeth on the posterior margins of the uropodal exopod and endopod (
Kensley &
Heard
1990: fig. 4C
). The distally bidentate tip of the antennal acicle, a unique configuration within the genus, is most probably a result of the extreme shortening of the main (lateral) tooth, with the distomesial tooth thus corresponding to the more proximally situated mesial tooth in several other species of
Axianassa
(see below).
The
holotype
of
A. mineri
is a female missing its left cheliped (
Boone 1931
;
Kensley &
Heard
1990
). The present material, composed of three complete specimens (two males and one female), suggests that the right cheliped of the
holotype
(
Boone 1931
: fig. 10;
Kensley &
Heard
1990
: fig. 4B) is most likely the female major cheliped (
Fig. 1
B). The male major cheliped (shown
in situ
in
Fig. 2
C) appears to be stouter and with stronger teeth on the cutting edges of the fingers, but otherwise is very similar to that of the female (
Fig. 1
B, 2B). The female and male minor chelipeds (shown
in situ
in
Fig. 2
B, C) are also similar, except for their proportions (stouter in male), and appear to be fairly typical for the genus. In both sexes, the minor cheliped pollex is armed with several strong subacute teeth on the cutting edges, in addition to a row of smaller blunt teeth (e.g.,
Fig. 2
C).
Axianassa mineri
appears to be ecologically different from the other eastern Pacific species (see below) by inhabiting mixed rocky-sandy shores, where it can be most easily collected at low tide by flipping rocks or larger pieces of coral rubble dispersed on muddy sand.