Palapedia apeli, Naderloo, Reza, 2015

Naderloo, Reza, 2015, Two new species of Palapedia Ng, 1993 (Crustacea, Decapoda, Brachyura, Xanthidae) from the Persian Gulf, Zootaxa 3994 (2), pp. 265-274 : 270-271

Palapedia apeli n. sp.

( Figs. 2 a–b, 4a–f, 5d–f)

Kraussia ( nitida Stimpson ?) Stephensen 1946: 138, fig. 33.

Palapedia sp. nov. Apel 2001: 88 (Part of the material from Bahrain, Persian Gulf).

Material examined. Holotype: 1 male (CL = 9.63 mm, CB = 9.91 mm) ( ZMUC CRU- 945), Bahrain, Persian Gulf, gravel, 23 m, 27 Mar. 1937, coll. G. Thorson & B. Loppenthin.

Description. Carapace round ( Figs. 2 a, 4a), very slightly broader than long (CB/CL about 1.03); posterior surface of carapace gently convex, finely tuberculate, small tubercles in transverse rows, usually two to four tubercles in row, getting denser on lateral portions, especially denser on anterolateral portion; carapace regions not defined, gastric region relatively smooth, with fewer tuberculate, weakly defined by posterior depression. Frontal breadth about 0.31 times carapace breadth, slightly shorter than posterior margin of carapace, with two produced lobes, lobes anteriorly denticulate, distinctly concave, separated by V-shaped notch from each other, shallow furrow extending backward on frontal region, front distinctly produced beyond inner orbital angle, separated from them by small notch. Inner orbital angle with large denticles, supraorbital margin markedly concave, with median deep fissure, lateral margin with large denticles, exorbital angle with larger denticle; infraorbital margin slightly concave medially, with relatively large denticles; inner angle hardly reaching to distal margin of first antennal segment; outer angle separated from exorbital angle by narrow V-shaped fissure. Lateral margins of carapace irregularly denticulate, with long setae; anterolateral margins distinctly arched, very longer than posterolateral margins, slightly larger denticle distinct on epibranchial margin; posterolateral margins concave, finely granulate. Eyestalks short, denticulate on anterior margin, large denticles on distal part. Antennules obliquely folded, basal segment nearly triangular, finely granulate on anterior part. Antenna with basal antennal segment slightly longer than broad, distinctly separated from inner orbital angel with wide hiatus, as long as second segment, second segment slightly longer than third one. Third maxillipeds ( Fig. 4 b) with ischium about twice as long as merus, smooth on outer surface, inner margin faintly tuberculate; merus subquadrate, slightly wider than long, with small granules on outer surface. Thoracic sternum 3–4 fused, without any suture, slightly arched laterally.

Male chelipeds subequal. Merus about 1.7 times as long as breadth, outer, inner surfaces smooth, margins faintly granulate, serrated with long setae. Carpus nearly as long as merus, granulate on distal inner surface, large denticles on distal inner margin. Manus robust ( Fig. 4 d), its height slightly more half as long as whole manus length; outer surface mostly smooth, granules on upper distal part of outer surface, faint longitudinal furrow distally on lower portion; inner surface smooth; upper margin with few granules, lower margin smooth. Movable finger with two longitudinal furrows along upper margin, median ridge proximally faintly dentate, patch of long setae on inner, outer surfaces; cutting edge with median blunt tooth. Immovable finger short, with median blunt tooth on cutting edge, patch of long setae on inner, outer surfaces. Smaller chelipeds ( Fig. 4 e) with elongated manus, fingers, fingers without blunt tooth on cutting edge.

Ambulatory legs margins with long setae; merus about 2.5 times as long as broad, surfaces, margins smooth; carpus as long as merus, anterior margin with distal denticles; propodus shorter than other segments, with larger denticles along anterior margin; dactylus long spade-shaped, smooth, anterior margin nearly straight, slightly concave, posterior margin markedly arched ( Fig. 4 c).

Male abdomen long, three first somites visible from dorsal view of carapace; somites 3–5 tightly fused; somite 6 medially concave, about 1.6 times as long as breadth, telson short triangular, apically truncate.

Male G1 narrow ( Fig. 5 d–f), long, apically bent inward with around 60 degree; long setae subapically along lateral margin, getting longest on apical part. G2 short, distal process relatively long, tapering distally, basal segment narrow, with extended lateral process ( Fig. 5 h).

Distribution. This species is only known from the type locality in Bahrain, Persian Gulf.

Etymology. The species named after Michael Apel, whose contribution to this genus in the Persian Gulf is the foundation of the present study.

Remarks. The material of Palapedia apeli n. sp. was first recorded by Stephensen (1946) from the Persian Gulf and was hesitantly placed in P. nitida (Stimpson, 1858) , as “ Kraussia ( nitida Stimpson ?)”. Apel collected more specimens of the genus from the Persian Gulf and placed all together with Stephensen’s (1946) material in an undescribed species of Palapedia . Detailed examination of the material showed clear differences between Stephensen’s (1946) material collected from Bahrain and those collected by Apel (2001) from Saudi Arabia in the Persian Gulf and both are described as a new species. Kraussia ( nitida Stimpson ?) of Stephensen (1946) is here described as a new species, Palapedia apeli n. sp., and is distinct from P. persica n. sp. by having a distinct G1; smooth appendages, in particular the dactylus of chelipeds and ambulatory legs; smaller teeth on the anterolateral margin of the carapace; and having frontal lobes that are anteriorly concave and distinctly separate from inner orbital angles. A distinct and less familiar character of the new species is a distinct gap between the basal antennal segment and the inner angle of the infraorbital margin, whereas there is no gap between these two parts in P. persica n. sp. and the other known species. Regarding the dentition of the chelipeds and ambulatory legs, P. apeli is similar to P. valentini Ng, 1993 , from Singapore, and P. nitidus , most likely restricted to Japan (Ng 1993), but is distinguishable from them by the unique morphology of the apical part of the G1. The G1 of the new species is similar to that of P. roycei (Serène, 1972) , described from Australia, but the apical process in P. roycei is bent laterally at about 45˚ (Serène, 1972: fig. 9), whereas in P. apeli the apical process is bent laterally at 90˚ and ends in a small finger-shaped process.

Figures

FIGURE 2. Palapedia apeli n. sp. Male holotype (ZMUC CRU- 945). a, dorsal view; b, ventral view.

FIGURE 4. Palapedia apeli n. sp. Male holotype (ZMUC CRU- 945 )), CL = 13.41, CB = 15.14 mm: (a) posterior surface of carapace; (b) third maxilliped, outer surface; (c) last ambulatory leg, left; (d) large cheliped, outer surface; (f) small cheliped, outer surface.

FIGURE 5. Palapedia persica n. sp. Male paratype (SMF pending): (a) G 1, abdominal surface; (b) apical part of G 1, abdominal surface; (c) apical part of G 1, dorsal surface; (g) G 1, lateral view. Palapedia apeli n. sp. Male holotype (SMF pending): (d) G 1, abdominal surface; (E apical part of G 1, abdominal surface; (f) apical part of G 1, dorsal surface; (h) G 1, lateral view.