Salmoneus excavatus Anker, 2011, sp. nov.
Creators: name: Anker, Arthur
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Alpheidae
Salmoneus
Salmoneus excavatus

description: Salmoneus excavatus sp. nov.
Figs. 1–3
Type material. Pacific coast of Panama. Holotype: 1 ovig. specimen (cl 4.9 mm), MNHN-IU-2011-5173, southwest of Ciudad de Panamá, Chumical, rock-sand intertidal, night low tide, leg. A. Anker [fcn 07-104A]. Paratypes: 1 non-ovig. specimen (cl 5.3 mm), RMNH D53455, same collection data as for the holotype [fcn 07-104B]; 1 ovig. specimen (cl 3.6 mm), OUMNH.ZC. 2011-06-015, southwest of Ciudad de Panamá, near Veracruz, beach in front of Isla Venao, rock-sand intertidal, low tide, leg. A. Anker, C. Hurt, J.A. Baeza, 0 6.12.2006 [fcn 06-619].
Additional (non-type) material examined. Pacific coast of Colombia. 1 non-ovig. specimen (cl not measured), MHNMC, Bahía Malaga, Los Negros (entrance of Bahía Malaga), 03°59’22,7’’N 77°17’46,6’’W, ARMS on sand-rock bottom, 2 m, leg. J.F. Lazarus-Agudelo, A. Anker, and others, 25.04.2009 [fcn COL-00140].
Description. Small-sized alpheid shrimp (cl range 3.6–5.3 mm). Rostrum well developed, longer than broad at base, with acute tip, latter not reaching mid-length of second article of antennular peduncle; lateral margins shallowly concave in dorsal view; ventral margin with minute tooth subdistally; rostral carina inconspicuous (Fig. 1 A– C). Orbital teeth small, acute, directed mesially (Fig. 1 A). Pterygostomial angle slightly protruding anteriorly, rounded (Fig. 1 B). Carapace sparsely covered with setae; dorsal surface with deep, dent-like, narrowly ovoid, longitudinal depression, starting at about 1/3 carapace length (more or less above pterygostomial angle) and ending at some distance from posterior margin of carapace; lateral margins of median depression slightly elevated, appearing as low longitudinal ridges; anterior end of depression with weak tubercle or elevation on mid-dorsal line (Fig. 1 D– F).
Sternum with rounded process between bases of second pereiopods. Pleuron of fifth abdominal somite with subacute, non-projecting posteroventral angle; sixth somite without articulated plate, sharply produced posteriorly; preanal plate with subacute point posteriorly (Fig. 1 G, H).
Telson widest in proximal third, distally tapering; dorsal surface typically with two pairs of stout spiniform setae (occasionally missing), inserted at some distance from lateral margin, at about 0.5 and 0.75 telson length, respectively; posterior margin approximately half as long as anterior margin, with U-shaped median incision; two pairs of stout spiniform setae present at posterolateral angles, mesial distinctly longer than lateral; median incision furnished with three pairs of slender plumose setae (Fig. 1 I, O).
Eyes concealed in dorsal and lateral views, with blunt lateral process; cornea well developed (Fig. 1 A, B). Epistomial sclerites with short, blunt processes.
Antennular peduncles stout, with second article clearly longer than wide; stylocerite pressed tightly against peduncle, with subacute tip falling short of distal margin of second article (Fig. 1 A); ventromesial carina with strong, anteriorly directed tooth, as illustrated (Fig. 1 J); lateral flagellum biramous, fused portion with three articles, accessory ramus well developed, with at least seven groups of aesthetascs (Fig. 1 B). Antenna with basicerite ending in stout distoventral tooth; scaphocerite ovate, with broad, anteriorly rounded blade reaching slightly beyond tip of stout, sharp distolateral tooth; carpocerite short, reaching about 3/4 length of scaphocerite (Fig. 1 B, K).
Mouthparts typical for genus in external view. Third maxilliped slender; coxa with rounded lateral plate above mastigobranch; penultimate article at least four times as long as wide, slightly widening distally; ultimate article somewhat broadened, tapering distally, with dense transverse rows of thick serrulate setae mesially, apex with corneous tip and small subdistal spiniform seta; arthrobranch well developed (Fig. 2 A).
Chelipeds very unequal in size and asymmetrical in shape; minor cheliped much shorter, more slender, with a much smaller, non-enlarged chela; both chelipeds folded when not in use (Fig. 2 B, C, E). Major cheliped moderately long and robust; ischium distally widening, unarmed; merus distally widening, flattened ventrolaterally; carpus short, cup-shaped, embracing proximal portion of palm; palm with deep proximo-mesial excavation, both dorsal and ventral surfaces hollowed, forming dent-like, longitudinal excavations; fingers about as long as palm, with tips curved and crossing when closed; cutting edges serrate with about 9–11 mostly subtriangular teeth, proximal teeth on dactylus broader and truncate distally, somewhat molar-shaped, most-distal portions of cutting edges without teeth (Fig. 2 B–D). Minor cheliped with unarmed ischium; merus about four times as long as wide; carpus as long as merus, distally slightly widening; chela simple, with fingers somewhat gaping, and slightly longer than palm; cutting edges smooth (Fig. 2 E, F).
Second pereiopod slender; ischium with spiniform seta; merus longer than ischium; carpus five-articulated, first article being equal to sum of four others, ratio of carpal articles (from proximal to distal) approximately 4: 1: 0.8: 0.9: 1.6; chela simple, distinctly longer than most-distal carpal article (Fig. 2 G). Third pereiopod moderately slender, compressed; ischium with two spiniform setae on ventrolateral surface; merus more than five times as long as wide, unarmed; carpus more slender than merus, about 0.6–0.7 merus length, with slender spiniform seta distoventrally; propodus with three slender spiniform setae along ventral margin and one pair of longer spiniform setae on distoventral edge, adjacent to dactylus; dactylus about half as long as propodus, slender, gradually curving, with some setae at about 0.7 dactylar length (Fig. 2 H). Fourth pereiopod generally similar to third. Fifth pereiopod somewhat longer and more slender than third and fourth pereiopods; ischium unarmed; merus subequal to carpus; propodus with some small spiniform setae along ventral margin and two longer spiniform setae distally, setal brush composed of at least 15 rows of serrulate setae becoming longer distally (Fig. 2 I).
Second pleopod with appendix masculina not exceeding appendix interna, with row of stiff setae, as illustrated (Fig. 1 L). Uropod with lateral lobe of protopod bearing sharp tooth; endopod and exopod ovoid; diaeresis mostly straight, with small blunt tooth adjacent to stout spiniform seta (Fig. 1 M). Gill-exopod formula typical for genus (see Anker & Marin 2006).
Colour in life. Whitish to pale yellow, with slight pinkish tinge on antennules, antennae and tail fan; eggs yellow (Fig. 3).
Etymology. From Latin word excavatus (excavate, hollowed), referring to the deep excavation on the carapace; used as an adjective.
Type locality. Chumical and Veracruz, southwest of Ciudad de Panamá (Panama City), Pacific coast of Panama.
Distribution. Presently known only from the Pacific coast of Panama (southwest of Panama City) and Colombia (Bahía Malaga).
Ecology. Low intertidal and shallow subtidal, known depth range 0–2 m; rocky-sandy intertidal with abundance of large rocks; most specimens were found on fine sand deep under large rocks. Remarks. See under the following species.
description: Published as part of Anker, Arthur, 2011, Two new species of Salmoneus Holthuis, 1955 with a deep dorsal depression on the carapace (Crustacea, Decapoda, Alpheidae), pp. 39-50 in Zootaxa 3041 on pages 40-44, DOI: 10.5281/zenodo.201843