Aegla saltensis Bond-Buckup & Jara

Bond-Buckup, Georgina, Jara, Carlos G., Buckup, Ludwig, Bueno, Alessandra A. P., Pérez-Losada, Marcos & Crandall, Keith A., 2010, Description of a new species of Aeglidae, and new records of related species from river basins in Argentina (Crustacea, Anomura), Zootaxa 2343, pp. 18-30 : 19-22

Aegla saltensis Bond-Buckup & Jara new species

( Fig.1 a–e)

Material examined. Holotype: male, Argentina, Province of Salta, Pasaje River at Route 34, 25°07'52"S, 65°00'54"W, 746 M, 08.xii.2001, coll. G. Bond-Buckup, C. Jara, M. Perez-Losada ( MZUSP 20466 ). Paratypes: Argentina, 3 females ( UFRGS 3359 P), same data as the holotype; Province of Salta , Juramento River below Penas Blancas Reservoir , 13.xii.1984, Grosso, L. col., FML 0 0 490, 1M, 1F.

Diagnosis. Anterolateral spine of carapace extending beyond base of cornea; protogastric lobes absent; extraorbital sinus narrow, V-shaped; rostrum triangular, carinate along its entire length, strongly deflected, proximal outer margin of moveable finger of cheliped without lobe; fingers of cheliped without lobular tooth; palmar crest of cheliped absent; anterior angle of ventral margin of epimera 2 unarmed; inner margin of ventral face of ischium of cheliped with one distal spine and a small proximal tubercle; dorsal margin of carpus of second and third pereiopods with one distal spine followed by scale-shaped tubercles.

Description. Carapace moderately convex, area of gastric region elevated, dorsal surface scabrous, covered with small scales and punctations.

Front narrow; PCW/FW ratio of male holotype 1.96.

Rostrum triangular, elevated from medial to distal portion, strongly deflected, of medium length, broad at base and tapered at extremity, indented in middle, carinate to apex. Subrostral process absent; in profile, rostrum with dorsal part higher than ventral part. Rostral carina beginning between protogastric lobes and epigastric prominences, with two parallel, closely set rows of pronounced scales that soon after form single row on distal third. Lateral margins of rostrum scaly.

Orbits moderately broad, shallow, bounded externally by small orbital spine. Orbital margin with few scales. Extraorbital sinus narrow, V-shaped.

Anterolateral angle of carapace projected anteriorly by spine extending beyond base of cornea. Outer margin of anterolateral lobe with scale-shaped tubercles; inner margin unarmed.

First hepatic lobe delimited anteriorly by small fissure; lateral margin with subequal, scale-shaped tubercles; 2nd and 3rd hepatic lobes not delimited, with only modest incision; lateral margins with subequal, scale-shaped tubercles.

Epigastric prominences little defined, low, of indefinite shape, elongated toward base of 1st hepatic lobe, with few scales. Protogastric lobes absent; anterior margin marked only by several scales.

Transverse dorsal line slightly sinuous. Areola subrectangular to rectangular, with margins subparallel in their entire length. AL/AW of male holotype: 1.87.

Epibranchial area triangular, well developed, with one apical tubercle followed by smaller, scale-shaped tubercles. Lateral margins of anterior and posterior branchial area with subequal, scale-shaped tubercles.

Anterior angle of ventral margin of epimera 2 unarmed; ventrolateral margin slightly convex; posterior angle of ventral margin unarmed ( Fig.1 d). Epimera of 3rd to 6th segments produced; lateral projection on 3rd and 4th ornamented with small apical tubercle.

Telson divided by longitudinal sulcus.

Anterior extremity of third sternite truncate, projecting between coxae of exopodites of third maxillipeds. Fourth thoracic sternite flat, lateral margins not recurved; Anterolateral margin projecting, with one tubercle; tuft of long setae, transversely on anterior part of segment ( Fig.1 e).

Cheliped unequal, hand subrectangular. Major cheliped globose, palm inflated in posterolateral region, covered by corneal scales. Minor cheliped more tapered. Palmar crest absent. Pre-dactylar lobe forming small step with anterior margin of propodus. Fingers thickened and covered with scales. Proximal outer margin of moveable finger without lobe. Prehensile margins of fingers with scale-shaped denticles along their entire length, however without opposing, dovetailed lobular teeth, with a space between the teeth. Dorsal face of carpus rugose, with scales; inner margin with three to four spines, distal spine most robust of the group; these spines with a few spinules on lateral margins; inner anterolateral angle subobtuse, with apical tubercle; anterodorsal margin with scales. Carpal crest modestly pronounced, especially at proximal region, with scales in groups of three to five on elevations of crest; crest absent in distal region, with few scales; outer ventral angle of carpus with one spine; ventral face with one conical spine. Dorsal margin of merus of cheliped with one, more-pronounced distal spine, remaining margin with scale-shaped tubercles; anterodorsal margin with scales. Lateral faces scabrous, with scales. Inner ventral margin of merus with one distal spine and several smaller tubercles; outer ventral margin with prominent distal tubercle, followed by scale-shaped tubercles ( Fig.1 c). Dorsal margin of ischium with elevation ornamented with scales; inner margin of ventral face with one, more-prominent distal spine, and two or three smaller tubercles arranged along the margin.

Dorsal margin of dactylus, propodus, and carpus of 2nd, 3rd, and 4th pereiopods with longitudinal rows of scales. Carpus of 2nd and 3rd pereiopods armed anterodorsally with one scale-shaped tubercle.

Variations. The three female paratypes have more prominent spines. On the proximal outer margin of the moveable finger there are several scales, suggesting the presence of a lobe. The anterior margin of the propodus of the paratypes has a strong spine followed by several tubercles ornamenting the region of the palmar crest, without, however, constituting a palm.

Measurements. Male holotype 29.1 mm CL. Mean of paratypes 21.1 mm CL (n = 5 (1M, 4 F).

PCW/FW ratios of paratypes ranging from 1.89–2.11, mean 2.05. AL/AW ratios of paratypes ranging from 1.52–1.90, mean 1.76.

Distribution. ARGENTINA: Parana River system - Province of Salta, Pasaje River or Juramento River.

Discussion. The new species, Aegla saltensis , is quite close to Aegla jujuyana Schmitt , sharing the absence of a proximodorsal lobe on the moveable finger and a lobular tooth on the cutting edge of cheliped, thus with palmar crest absent. It is distinguished from A. jujuyana by the more globose hand; by the definition of the pre-dactylar lobe of the cheliped, by the longer rostrum, by the presence of the carpal crest, and by the absence of ornamentation on the anterior angle of the ventral margin of epimera 2. Although the shape of the rostrum is similar in both species, that of A. saltensis is much more deflected, comparable in this respect only to that of the Brazilian species A. obstipa . The globose major cheliped, with the palm inflated in the posterolateral region, is similar to that of A. septentrionalis and A. affinis ; however, these have the rostrum lingulate, much different from the new species.

One of the most marked characters of A. saltensis , the absence of the palmar crest, is uncommon in aeglids, occurring only in A. jujuyana , A. uruguayana , A. marginata , and A. septentrionalis . These latter three species, however, do not share other characters with the new species.

Biology: Unknown.

Etymology: Named in honor of Salta Province, the type locality.

Figures

FIGURE 1. Aegla saltensis new species, male holotype (MZUSP 20466): a, dorsal view; b, pre-cervical portion of carapace, side view; c, inner margin of ischium of cheliped; d, lateral view of second abdominal epimeron; e, third and fourth sterna, ventral view. (Scale: 8 mm).