Leptalpheus canterakintzi 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
Alpheidae
Leptalpheus
Leptalpheus canterakintzi

description: Leptalpheus canterakintzi sp. nov.
(Figs. 5-7)
Type material: Holotype: 1 male (cl 6.0 mm, dissected), INV CRU8363, Colombia, Bahía Málaga, Curichichi, 03°59’37.8”N, 77°19’03.9”W, intertidal mudflat, low tide, in burrow of Axianassa darrylfelderi sp. nov., leg. A. Anker, 26.iv.2009 [COL-00177].
Description: Carapace with frontal margin roundedsubtriangular, with minute median rostral projection; pterygostomial angle angular-rounded, not anteriorly produced; branchiostegial margin with pronounced lip (Fig. 5A, B); posterior margin with deep cardiac notch.
Pleon with all pleomeres rounded; sixth pleomere with well-demarked subtriangular articulated plate. Telson widest at about proximal third, smoothly tapering distally; dorsal surface with two pairs of strong spiniform setae inserted in deep pits at some distance from lateral margin; posterior margin rounded, with two pairs of spiniform setae at each posterolateral angle, lateral spiniform setae minute, much shorter than mesial; margin between mesial spiniform setae with at least 18 long plumose setae (Fig. 5C).
Eyestalks with anteromesial margin rounded, slightly protruding; anterior surface furnished with setae; dorsal surface with small tubercle; process lateral to eyestalks and adjacent to antennular base very strong (Fig. 5A, B, D).
Antennular peduncles stout, flattened dorsoventrally; stylocerite slightly convex laterally, with subacute point slightly overreaching distal margin of first article; ventromesial carina of first article with complex tooth comprising small sharp point ventrally and larger subacute lobe, reaching far beyond sharp point, dorsally; second article about 1.2 times as long as wide; lateral flagellum with long secondary ramus furnished with at least three tufts of aesthetascs (Fig. 5A, B, E). Antenna with stout basicerite ending in stout sharp distoventral tooth; scaphocerite oval, with small subacute distolateral tooth, not reaching beyond anterior margin of very broad blade; carpocerite stout, reaching far beyond scaphocerite and end of antennular peduncle; flagellum robust (Fig. 5A, B).
Mouthparts (mandible, maxillule, maxilla, first and second maxillipeds) not dissected, typical for genus in external view (cf. Dworschak & Coelho, 1999: figs. 8-13). Third maxilliped with lateral plate on coxa projecting towards but not reaching beyond arthrobranch, distally subacute; ultimate article about as long as antepenultimate, with dense bands of thick setae, tip without spiniform setae (Fig. 5F).
Chelipeds highly asymmetrical in shape and unequal in size, both folded when not in use (Figs. 6, 7). Major cheliped slender proximally, but with robust chela; ischium relatively short, unarmed; merus slender, slightly curved, depressed ventrally, with smooth surfaces; carpus very short, cup-shaped; chela somewhat elongate, stout, with palm depressed ventrally, smooth; fingers about 0.6 palm length, slightly twisted, nearly non-gaping when closed (except for very small subdistal gap); with stout, broadly subtriangular tooth proximally, and stout molar-shaped tooth, nearly perpendicular to main axis of pollex, distally, both teeth bypassing dactylus on lateral side of pollex; tip of pollex blunt; dactylus with large bulge bypassing pollex on mesial side; adhesive disks well developed (Fig. 6 A-C). Minor cheliped much smaller than major cheliped; ischium smooth; merus slender, ventrally depressed, with smooth surfaces; carpus very short, cup-shaped; chela moderately slender, simple, with fingers somewhat shorter than palm, with crossing tips; cutting edge of dactylus with four small spaced teeth, most proximal tooth situated at about mid-length, most distal tooth largest, situated at about 0.7 length of dactylus; cutting edge of pollex with numerous (about 12) small teeth on proximal 0.7 length, becoming slightly larger and more spaced distally, in addition to larger tooth at 0.7 length of pollex, opposed (slightly proximal) to similarly sized tooth on dactylus (Fig. 6D, E).
Second pereiopod with merus slightly longer than ischium but much shorter than carpus; carpus five-articulated, with article ratio approximately equal to 4.5: 1.0: 1.3: 1.0: 2.0 (Fig. 5G). Third pereiopod moderately slender, compressed; ischium lacking spiniform seta on ventrolateral surface; merus about 5.3 times as long as wide; carpus about 0.4 length of merus, with distoventral spiniform seta; propodus with three slender spiniform setae along ventral margin, including one adjacent to dactylus; dactylus about half length of propodus, conical, slender, slightly curved, acute distally (Fig. 5H). Fourth pereiopod similar to third, slightly smaller and more slender. Fifth pereiopod much more slender than third and fourth, not compressed; carpus about 0.7 length of merus; propodus with well-developed grooming brush distolaterally, consisting of at least four rows of short setae, ventromesial margin with two slender spiniform setae; dactylus nearly half as long as propodus, conical, slender, curved, acute distally (Fig. 5I).
Male second pleopod with slender appendix masculina significantly exceeding appendix interna, with at least seven stiff setae, mostly on or near apex (Fig. 5J). Uropod with lateral lobe of protopod ending in two small, sharp, somewhat spaced teeth; exopod with distal margin broadly rounded; diaeresis with straight lateral portion, rather shallow mesial incision flanked by broad rounded tooth near mesial margin (Fig. 5K).
Gill-exopod formula typical for genus (cf. Anker, 2011b: p. 3).
Colouration: Semitransparent with reddish chromatophores forming large pale red-pink patches, especially on antennules, antennae, tail fan, and diffuse reddish transverse bands on pleon; chelae distally hyaline white; pereiopods mostly colourless (Fig. 7).
Etymology: The new species is named after Dr. Jaime R. Cantera-Kintz (Universidad del Valle, Cali, Colombia), for his engagement in the progress of marine biology in Colombia and unconditional support to JFL in his academic career. Additionally, Dr. Cantera-Kintz arranged and organised several surveys of the marine invertebrates of Bahía Málaga, and enabled AA to participate in one of them, in April 2009.
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 of Axianassa darrylfelderi sp. nov., mostly in lower, rock-free part of the mudflat.
Remarks: Leptalpheus canterakintzi sp. nov. represents, beyond any doubt, the eastern Pacific sister species of the morphologically almost identical western Atlantic L. axianassae. The two transisthmian sister species can be reliably distinguished only by the proportions of the third pereiopod, viz. by the somewhat shorter propodus (about half-length of merus in L. canterakintzi sp. nov. vs.> 0.6 length in L. axianassae) and the more slender merus (~5.3 times as long as wide in L. canterakintzi sp. nov. vs. 4.3 to 4.5 times as long as wide in L. axianassae) (cf. Figs. 5H and 8B). The difference in the propodus length may be best appreciated when the leg is completely folded, with the dactylus tip pointing to the distal quarter of the ischium in L. canterakintzi sp. nov. vs. to the midlength of the ischium or its proximal third in L. axianassae. In all examined specimens of L. axianassae, the merus of the third pereiopod is slightly stouter compared to that of L. canterakintzi sp. nov., and also stouter than the merus of the fourth pereiopod. For instance, in both paratypes of L. axianassae (MZUSP 13010), the merus of the third pereiopod is about 4.5 times as long as wide, which corroborates the proportions shown in Dworschak & Coelho’s (1999) fig. 1, but not the proportions in their fig. 24, in which the merus is noticeably more slender, being nearly identical to that of the fourth pereiopod. This discrepancy may be due either to a slight inaccuracy of Dworschak & Coelho’s (1999) fig. 24 or to the somewhat abnormal proportions of the third pereiopod (e.g., after an early regeneration of the appendage).
Other differences initially scored between L. canterakintzi sp. nov. and L. axianassae appear to be inconsistent. The shape of the frontal margin of the carapace appears to be more broadly rounded in the eastern Pacific species, compared to the more triangularly shaped in the western Atlantic species (cf. Figs. 5A and 8A; see also Dworschak & Coelho, 1999: fig. 2). However, in L. canterakintzi sp. nov., it bears a minute rostral point (visible only at higher magnification), whereas in the female paratype of L. axianassae (MZUSP 13010), the frontal margin is untypically rounded and has two shallow lateral bumps, thus indicating some variation of this feature at least in the western Atlantic species. Dworschak & Coelho’s (1999: fig. 30) illustration of the tail fan shows the diaeresis of the uropodal exopod of L. axianassae bearing a deep median incision, flanked by a large, bluntly triangular tooth. However, in all specimens of L. axianassae examined in the present study, including the paratypes, the incision is rather shallow and is flanked by a more rounded median tooth, a configuration nearly identical to that of L. canterakintzi sp. nov. (cf. Figs. 5K and 8C). Therefore, the frontal margin of the carapace and the diaeresis of the uropodal exopod cannot be used to distinguish the new species from L. axianassae.
Leptalpheus canterakintzi sp. nov. and L. axianassae share a number of characters with the eastern Pacific L. corderoae Salgado-Barragán, Ayon-Parente & Hendrickx, 2014 and L. azuero Anker, 2011, including the frontal margin of the carapace lacking dorsal crests, the general shape and proportions of the major cheliped, the more or less stout antennular peduncles, and the ventromesial carina of the first article of the antennular peduncle with a uniquely shaped tooth, bearing a small sharp point ventrally and a large subacute lobe dorsally, the latter reaching to or beyond the former (cf. Fig. 5E and Dworschak & Coelho, 1999: fig. 6; Anker, 2011b: fig. 5D; Salgado-Barragán et al., 2014: fig. 2C). However, L. canterakintzi sp. nov. can be easily separated from L. corderoae by the smooth ventral surface of the major chela palm and pollex (vs. with large tubercles or pustules in L. corderoae), the much stouter antennular peduncles, with a much less appressed stylocerite, the ventromesial carina of the first article of the antennular peduncle with the dorsal lobe reaching far beyond the ventral sharp point (vs. equal in L. corderoae), and the uropodal exopod with a much shallower incision flanked by a rounded tooth mesially (vs. much deeper and flanked by a acutely triangular tooth in L. corderoae) (cf. Figs. 5A, E, 6 A-C and Salgado-Barragán et al., 2014: figs. 2A, C, G, 4A-C).
Leptalpheus canterakintzi sp. nov. also differs from L. azuero, previously known only from Panama and here recorded for the first time from Colombia, based on a single damaged specimen from Bahía Málaga (see under Comparative material). The two most important features separating the new species from L. azuero are the absence of a stout spiniform seta on the ischium of the third and fourth pereiopods in L. canterakintzi sp. nov. (present in L. azuero) and the pollex of the major chela terminating in a single tooth perpendicular to the pollex axis in L. canterakintzi sp. nov. (vs. with a strongly bidentate tip, i.e. with an additional tooth slightly oblique to the pollex axis, in L. azuero) (cf. Figs. 5H, 6A, B and Anker, 2011b: fig. 5H, 6D).
The general shape and armature of the major cheliped, the shape of the frontal margin of the carapace, the stout antennular peduncle, and the peculiar shape of the tooth on the ventromesial carina of the first article of the antennular peduncle are all features in support of a small species complex, most likely forming a monophyletic clade, that includes L. canterakintzi sp. nov., L. axianassae (sister taxa), L. corderoae and L. azuero. This clade differs substantially from all other American species of Leptalpheus (cf. Williams, 1965; Ríos & Carvacho, 1983; Anker et al., 2006a; Anker, 2008, 2011b) and shows some affinities with the three Indo-West Pacific species of the L. pacificus Banner & Banner, 1974 complex, especially in the general shape of the major cheliped (cf. Banner & Banner, 1974; Anker & Marin, 2009). An exhaustive cladistic analysis of morphological characters of all species of Leptalpheus and related genera (cf. Felder & Manning, 1986; Anker et al., 2006b; Anker & Jeng, 2006; Anker, 2011b; Marin et al., 2014), optimally combined with analyses of DNA sequences, is needed to answer the question whether Leptalpheus in its current definition represents a monophyletic group or, alternatively, needs a taxonomic rearrangement.
The material reported by Felder et al. (2003) as Leptalpheus sp. from the Pacific coast of Nicaragua has not been taxonomically studied until the present day; whether it represents L. canterakintzi sp. nov., L. corderoae, L. azuero or yet another undescribed species remains unknown.
Leptalpheus is now represented by five species in Colombia, three on the Pacific coast (all in Bahía Málaga), viz. L. canterakintzi sp. nov., L. azuero (present study) and L. mexicanus Ríos & Carvacho, 1983 (Ramos, 1995; Lazarus-Agudelo & Cantera-Kintz, 2007) and two on the Caribbean coast, viz. L. felderi Anker, Vera Caripe & Lira, 2006 and L. marginalis Anker, 2011 (Anker et al., 2006a; Anker, 2011b).
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 122-128, DOI: 10.1590/0031-1049.2015.55.08, http://zenodo.org/record/4656432