Axianassa darrylfelderi Anker & Lazarus 2015, sp. nov.
Creators: name: Anker, Arthur
name: Lazarus, Juan Felipe
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Laomediidae
Axianassa
Axianassa darrylfelderi

description: Axianassa darrylfelderi sp. nov.
(Figs. 1-4)
Type material: Holotype: 1 male (cl 11.5 mm, dissected), INV CRU8361, Colombia, Bahía Málaga, Curichichi, 03°59’37.8”N, 77°19’03.9”W, intertidal mudflat, low tide, in burrow, leg. A. Anker, 26.iv.2009 [COL-00192]; 1 ov. female (cl 9.0 mm, dissected), INV CRU8362, same collection data as for holotype [COL-00202]; 1 male (cl 9.7 mm), MZUSP 33014, same collection data as for holotype [COL-00200].
Description: Carapace with rostrum broad at base, apically rounded, not toothed, reaching well beyond anterior margin of eyestalks, fringed with setae; linea thalassinica straight, running entire length of carapace; cervical groove deep, crescent-shaped in dorsal view; branchiostegial margin slightly elevated; pterygostomial region rounded, not conspicuously protruding, fringed with setae; dorsal surface of carapace with few scattered setae, especially on frontodorsal and posterodorsal areas (Fig. 1 A-C).
Pleon thinly sclerotised, smooth; dorsal surface of tergites with scatteted setae of various length; ventral margin of second to sixth pleonites with dense rows of plumose setae; first pleonite ventrally produced into acute or subacute process, stronger in males (Fig. 1D). Telson broad, convex proximally, smoothly tapering posteriorly, posterior margin broadly rounded, neither lateral nor posterior margin with armature; dorsal surface with very shallow median groove (Fig. 1E).
Eyestalks rounded distally; cornea moderately developed compared to eyestalk, in subterminal position, well-pigmented (Fig. 1B).
Antennular peduncle with third article elongate, subcylindrical, slender, not reaching half-length of fourth article of antenna; ventral flagellum slender, less than half-length of dorsal flagellum (Fig. 1A). Antennal acicle dagger-like, relatively broad at base, tapering distally, with strong mesial tooth at about proximal third of acicle length, tip reaching to about 0.35 length of fourth antennal article, overreaching mid-length of third article of antennular peduncle; fourth antennal article subcylindrical, elongate, robust, about twice as long as third article of antennular peduncle, with numerous long setae on lateral and ventrolateral surface (Fig. 1A, F).
Mouthparts typical for genus (cf. Kensley & Heard, 1990: fig. 2d-i; Rodrigues & Shimizu, 1992: figs. 4-8; Anker, 2011a: fig. 2a-e; Komai, 2014: fig. 3a-e). Mandible with incisor process bearing eight large and two small triangular teeth distally; molar process with three large blunt processes distally; palp with three articles, distal article furnished with mostly short setae dorsally. Maxillule with ventral endite very large, with dense row of long setae distally, dorsal endite with spiniform setae; palp composed of two articles, distal recurrent, lacking setae. Maxilla with ventral endite entire, dorsal endite divided by deep cleft; endopod (palp) not subdivided, distally curved mesially, hook-like; scaphognathite with eight long setae ventrally. First maxilliped with ventral endite weakly protruding, moderately setose distally; dorsal endite large, with dense row of long setae distally; endopod (palp) two-articulated, with slender proximal article and very broad, lobe-like distal article; exopod composed of long, posteriorly greatly expanded proximal article, followed by and forming almost 90° angle with short subdistal article, latter carrying relatively short setose flagellum. Second maxilliped with coxa bearing posteriorly elongated epipod, latter with well-developed podobranch; three distal articles of endopod (dactylus, propodus and carpus) articulated perpendicularly to long proximal article, propodus enlarged, forming short “head”; exopod composed of long, posteriorly slightly widened proximal article, followed by and forming almost 90° angle with short subdistal article carrying moderately long setose flagellum.
Third maxilliped pediform; coxa with bifid epipod bearing well-developed podobranch, and with three relatively small subacute teeth (two stronger and one weak) on dorsomesial surface; ischium about as long as merus, with well-developed crista dentata bearing about 16 teeth, two most proximal teeth weakest; carpus vase-shaped, propodus as long as merus, dactylus about 0.7 length of propodus, ventral margin of ischium to dactylus with long fine setae (Fig. 1 G-J).
First pereiopods (chelipeds) stout, asymmetrical in shape, slightly unequal in size (Figs. 2 A-D, 3A, 4), smaller in females (Fig. 3B). Major cheliped robust; ischium with four or three strong sharp teeth on ventrolateral margin, and small tubercles irregularly scattered on ventral surface; merus inflated, with strongly convex dorsal margin and slightly convex ventromesial and ventrolateral margins; ventrolateral margin smooth, ventromesial margin with row of small, widely spaced tubercles, most concentrated in distal two thirds of merus length and near articulation with ischium; carpus large, cup-shaped, unarmed; chela ovate, somewhat compressed laterally; palm about 1.5 times as long as high (in adult males), with large fields of granules near base of pollex and near distodorsal margin, on both mesial and lateral surface, ventral granules usually larger; fingers about 0.6 length of palm, stout, with strongly crossing tips; lateral surface of pollex with low longitudinal ridge with small tubercles originating near distoventral margin of palm and more dorsally situated longitudinal ridge with tubercles, near cutting edge; mesial surface of pollex with smooth longitudinal ridge near cutting edge; cutting edges of pollex and dactylus armed with irregular blunt teeth, including two larger teeth separated by hiatus on proximal half of dactylus and one very stout tooth at about proximal third of pollex (Fig. 2A, B). Minor cheliped slightly smaller and less robust than major cheliped; ischium with two to four strong teeth on ventrolateral margin, and some minute tubercles on ventral surface, ventromesial margin slightly rugose; merus similar to that of major cheliped in proportions, ventromesial margin smooth, without tubercles; carpus similar to that of major cheliped; chela distinctly more slender, ovate; palm with small area of granules near pollex, more developed on mesial than on lateral surface; fingers slightly longer than palm, with fully crossing tips; lateral surface of pollex with ventral longitudinal ridge with small tubercles originating near distoventral margin of palm and more dorsally situated, faint longitudinal ridge with small tubercles, near cutting edge; mesial surface of pollex with row of tubercles proximally and longitudinal ridge with small tubercles along cutting edge; cutting edge of pollex armed with strong subtriangular teeth, including three or two conspicuously larger teeth (double teeth in males); cutting edge of dactylus with fairly strong teeth of about same size (Fig. 2C, D, I).
Second pereiopod moderately stout; merus, carpus and propodus with long setae along ventral margin; dactylus about half as long as propodus, simple, with crenulated ventral margin and numerous setae (Fig. 2E). Third pereiopod relatively robust, ischium, merus and carpus smooth, with few setae; propodus with distoventral brush of stiff setae; dactylus slightly shorter than propodus, dorsal margin with several corneous spines (easily broken off), distoventral margin slightly expanded, with comb-like row of minute spiniform setae (Fig. 2F). Fourth pereiopod similar to third, somewhat more slender (Fig. 2G). Fifth pereiopod much more slender than third and fourth; propodus subchelate, ending in short fixed tooth, latter typically concealed by dense setae; most of distal and ventral surface of propodus occupied by broad band of short stiff grooming setae; dactylus subspatulate, somewhat twisted and excavated mesially, with row of minute setae on edge (Fig. 2H).
First pleopod absent in males; first pleopod in females consisting of short base and longer distal article, latter fringed with setae along margins. Second to fifth pleopods similar, biramous; protopods unarmed. Uropod with broadly ovoid exopod and endopod, latter slightly truncate distally; both exopod and endopod unarmed dorsally, except for few minute tubercles marking insertion of setae; exopod without diaeresis, lateral margin with two or three small, rather widely spaced teeth (Fig. 1K).
Gill/exopod formula typical for genus (cf. Kensley & Heard, 1990: p. 559).
Colouration: Semitransparent with large areas of pink colour, latter being more intense on dorsal surface of carapace and pleon, antennal peduncles, chelipeds (especially merus, carpus and palm), near articulations on second to fourth pereiopods, and tail fan; eggs dark orange-red (Figs. 3, 4).
Etymology: The new species is named after our colleague, Dr. Darryl L. Felder (University of Louisiana, Lafayette, USA), for his important contributions to the taxonomy, biology and phylogeny of the American ghost- and mud-shrimps (Axiidea and Gebiidea).
Type locality: Bahía Málaga, Pacific coast of Colombia.
Distribution: Tropical eastern Pacific: presently known only from Colombia.
Ecology: Intertidal mudflat with abundance of large and small rocks, and some wood debris (Fig. 9), in burrows in muddy sand, mostly in lower, rock-free part of the mudflat.
Remarks: The most important taxonomic features of Axianassa darrylfelderi sp. nov. are the uropodal exopod lacking a diaeresis, the antennal acicle dagger-shaped and with a strong mesial tooth, the first pleonal somite ventrally with a stout sharp process, and the second to fifth pleura ventrally rounded. This combination of features is present in only two other species of the genus, viz. the western Atlantic A. australis Rodrigues & Shimizu, 1992, and the eastern Pacific A. canalis Kensley & Heard, 1990.
Axianassa darrylfelderi sp. nov. can be separated from A. australis by the presence of two or three small teeth on the lateral margin of the uropodal exopod (absent in A. australis); the longer antennal acicle (reaching to about 0.35 length of the fourth antennal article in A. darrylfelderi sp. nov. vs. less than 0.25 length of the fourth antennal article in A. australis); and the male minor cheliped armed with three strong double teeth, in addition to numerous smaller teeth, on the cutting edge of the pollex (vs. with one proximal double or triple tooth and two simple, more distal teeth in A. australis) (cf. Figs. 1A, F, K, 2C and Rodrigues & Shimuzu, 1992: figs. 3, 13, 20).
Axianassa canalis Kensley & Heard, 1990 is presently known only from a single incomplete specimen (missing both chelipeds) from the Pacific coast of Panama. The new species differs from A. canalis by the absence of a dense row of fusiform setae on the ventral surface of the third maxilliped ischium (present in A. canalis); the dorsomesial surface of the third maxilliped coxa with three relatively small teeth (vs. with one large tooth in A. canalis); the lateral margin of the uropodal exopod with two or three small teeth (vs. with one tooth in A. canalis); the protopods of the second to fourth pleopods posteroventrally unarmed (vs. with spinules in A. canalis); the longer antennal acicle (reaching to about 0.35 length of the fourth antennal article in A. darrylfelderi sp. nov. vs. less than 0.20 length of the fourth antennal article in A. canalis) (cf. Figs. 1A, F, H, K and Kensley & Heard, 1990: fig. 7; see also Rodrigues & Shimuzu, 1992 and Komai, 2014).
Axianassa darrylfelderi sp. nov. also appears to have some affinities with the western Atlantic A. jamaicensis Kensley & Heard, 1990, in which, however, the first pleonite is not ventrally produced into a stout spiniform process, as in the new species (cf. Fig. 1D and Kensley & Heard, 1990: fig. 6A). In addition, in A. darrylfelderi sp. nov., the ventromesial margin of the cheliped merus only bears small spaced tubercles, whilst in A. jamaicensis, it bears a fairly conspicuous sharp tooth, slightly posterior to the merus mid-length (cf. Fig. 2A, B and Kensley & Heard, 1990: fig. 6A).
Axianassa darrylfelderi sp. nov. can be more easily distinguished from the remaining American species of the genus, for instance, from the western Atlantic A. arenaria Kensley & Heard, 1990 by the antennal acicle bearing a mesial tooth (lacking in A. arenaria), a much wider telson, the second to fifth pleura ventrally unarmed (vs. each with a sharp tooth in A. arenaria), and the ventromesial margin of the major cheliped merus with small spaced tubercles (vs. with tubercles in proximal half and a strong sharp tooth at merus mid-length in A. arenaria); from the western Atlantic A. intermedia Schmitt, 1924 by the first pleonite ventrally produced into a spiniform process (ventrally unarmed in A. intermedia), the ventrolateral margin of the cheliped ischium armed with several strong teeth (vs. finely denticulate in A. intermedia), and the ventromesial margin of the cheliped merus with small spaced tubercles (major) or smooth (minor) (vs. both strongly serrated distally in A. intermedia); and from the eastern Pacific A. mineri Boone, 1931 by the shape of the frontal margin of the carapace (not forming a distinct rostral projection in A. mineri), the long, dagger-shaped antennal acicle (short and bidentate in A. mineri), and several conspicuous differences in the armature of the cheliped and uropod (cf. Figs. 1, 2 and Kensley & Heard 1990: figs. 1-5). The new eastern Pacific species presents even a greater amount of differences with the four Indo-West Pacific species (cf. Figs. 1, 2 and figures in Anker, 2010, 2011 a, Liu & Liu, 2010; Komai, 2014).
Felder et al. (2003) reported Axianassa cf. canalis from the Pacific coast of Nicaragua, a taxon closely related to A. australis based on its position in the molecular tree in fig. 8. Whether the Nicaraguan material corresponds to A. darrylfelderi sp. nov., A. canalis or yet another species remains unknown.
description: Published as part of Anker, Arthur & Lazarus, Juan Felipe, 2015, Description of two new associated infaunal decapod crustaceans (Axianassidae and Alpheidae) from the tropical eastern Pacific, pp. 115-129 in Papéis Avulsos de Zoologia (São Paulo) (São Paulo) 55 (8) on pages 116-122, DOI: 10.1590/0031-1049.2015.55.08, http://zenodo.org/record/4656432