INTRODUCTION
Ghost shrimps or mud shrimps are common burrowing decapods in littoral and sublittoral marine environments. The number of known species of ghost shrimps continues to grow (Dworschak, Reference Dworschak2005). The number of accepted families in the Axiidea, the infraorder that includes ghost shrimps, is disputed, ranging from four (possibly nine) (Dworschak et al., Reference Dworschak, Felder, Tudge, Schram and von Vaupel Klein2012) to 19 (Sakai, Reference Sakai2011). The genus Gourretia de Saint Laurent, Reference de Saint Laurent1973 to which this new species belongs was placed in Gourretiidae Sakai (Reference Sakai1999) in Sakai's (Reference Sakai2011) comprehensive revision, but in Ctenochelidae Manning & Felder, Reference Manning and Felder1991 by Dworschak (Reference Dworschak2009), Liu & Liu (Reference Liu and Liu2010) and Pachelle et al. (Reference Pachelle, Bezerra and Anker2013). The most recent phylogenetic analyses involving both morphological and molecular data support the acceptance of the family Gourretiidae (Gary C.B. Poore, personal communication 23 August 2015) and the placement of Gourretia within it.
Sakai (Reference Sakai2011) included five genera within Gourretiidae and removed half of the 12 species of Gourretia then accepted into Paragourretia Sakai, Reference Sakai2004. Paragourretia, type species Gourretia phuketensis Sakai, Reference Sakai2002, was said to differ from Gourretia in possession of a lateral notch on the uropodal exopod but not all species possess such a notch. The 14 accepted species, in both genera, are listed in WORMS (Poore, Reference Poore2015). The new species lacks a uropodal exopod notch so its position within Gourretia is not in doubt.
Gourretia is characterized by: a carapace lacking dorsal oval; subpediform maxilliped 3, usually with distolateral meral spine, and with exopod present; larger cheliped with proximal meral hook; male pleopod l uniramous, biarticulate, distal segment distally bifurcate; male pleopod 2 biramous, foliaceous, and with digitiform appendix interna.
MATERIALS AND METHODS
Material was deposited in the Iranian Institute for Oceanology and Atmospheric Science (INIOAC). The drawings were made with the aid of a drawing tube mounted on a Nikon SMZ1500 stereomicroscope.
RESULTS
SYSTEMATICS
Family Gourretiidae Sakai, Reference Sakai1999
Genus Gourretia de Saint Laurent, Reference de Saint Laurent1973
Species Gourretia qeshmensis
sp. nov.
(Figures 1–3)
Fig. 1. Gourretia qeshmensis sp. nov. Holotype, INIOC-1-36S. (A) lateral view of body; (B) antenna; (C) dorsal view of carapace and cephalic appendages; (D) antennule and (E) telson; (F) details of telson and uropod. Scale bar: 1 mm.
Fig. 2. Gourretia qeshmensis sp. nov. Holotype, INIOC-1-36S. (A) maxilliped 1; (B) mandible; (C) maxilliped 2; (D) maxilliped 3, mesial face. Scale bar: 0.5 mm.
Fig. 3. Gourretia qeshmensis sp. nov. Holotype, INIOC-1-36S. (A) large cheliped, inner surface; (B) dactylus and fixed finger of large cheliped; (C) small cheliped, inner surface; (D) pereopod 2; (E) details of chelate in periopod 2; (F) periopod 3; (G) propodus and dactylus of periopod 3; (I) pleopod 1; (H) pleopod 3. Scale bar: 1 mm.
Holotype: Iran, Persian Gulf, west of Qeshm Island (26°35′12.87″N 55°8′0.67″E), INIOC-1-36S (male, total length 10.12 mm, carapace length 2.5 mm).
DESCRIPTION
Rostrum triangular in dorsal view more than 3/4 length of eyestalks (Figure 1C); lateral projections triangular. Carapace without dorsal oval, smooth, ornamented with tuft of setae on the branchial region; cardiac prominence absent; linea thalassinica complete; cervical groove located about in posterior quarter.
Ratio of lengths of pleomeres 1–6 and telson measured along midline 2.5: 2.2: 1.25: 1.25: 1.25: 1.6. Pleomere 1 (Figure 1A) longer than wide; pleura 3–5 with tuft of setae on posterolateral margins; pleomere 6 as long as wide, subquadrate in dorsal view, pleuron without row of setae. Telson (Figure 1E, F) 1.1 times as wide as long, basally parallel-sided, posterior margin tapering to rounded apex, without median spine. Uropodal endopod 1.2 times as long as wide, distally rounded, with marginal row of setae, without median carina on dorsal face; exopod subtriangular, widening distally, without dorsal plate, lacking lateral notch or incision, margins armed with spines, large setae and 4 strong spines at the distolateral corner (Figure 1F).
Eyestalk (Figure 1A, B) elongate, triangular in dorsal view with acute tip, reaching distal third article 1 of antennular peduncle; cornea in distal third, with small black pigmented area. Antennular peduncle (Figure 1C, D) shorter and wider than antennal peduncle; terminal article longer than penultimate. Antennal peduncle slender; terminal article shorter length as of penultimate article (Figure 1B, C).
Mandible (Figure 2B) with 9 acute teeth on incisor process, mandibular palp 3-articled, article 3 larger than others armed with tuft of setae.
Maxilliped 1 (Figure 2A) with endopod reaching near to apex of basal endite.
Maxilliped 2 (Figure 2C) with narrow 2-articled exopod just exceeding ischium, tip of endopod quadrate, exopod and endopod ornamented with setae.
Maxilliped 3 (Figure 2D) with narrow 2-articled exopod; ischium of endopod with projection ventroproximally, crista dentata of 8 teeth, proximal tooth biggest; merus with spinous projection distally; carpus proximally narrow, broad distally; propodus subovate; dactylus finger-like.
Pereopods 1 (chelipeds) unequal and dissimilar. Major cheliped (Figure 3A) strong; ischium elongate, 2.5 times as long as wide, upper margin slightly concave and unarmed; lower margin straight, armed with 6 strong teeth on ventral margin acute at tip; merus shorter than ischium, about 1.5 times as long as wide, upper margin convex, smooth, lower margin convex with a sharp curved proximal tooth; carpus 0.7 times as long as wide, upper margin straight, lower distal margin broadly rounded and smooth; propodus elongate, 1.5 times as long as wide; fixed finger as long as upper margin of palm, cutting edge with series of 7 Triangular teeth; dactylus slender, slightly incurved distally, bearing 6 rounded teeth on cutting edge (Figure 3B). Minor cheliped (Figure 3C), ischium 3 times as long as wide, upper margin slightly concave and unarmed, lower margin straight, armed with 7 sharp denticles; merus globose upper margin convex, smooth, lower margin almost straight, with a strong and sharp tooth at the proximal end; carpus 1.3 times as long as wide, upper margin almost straight, lower proximal margin gradually tapering to base; propodus elongate, 2.7 times as long as wide, fixed finger slender, cutting edge with series of 7 triangular teeth; dactylus slender, slightly overreaching fixed finger, cutting edge with series of 7 triangular teeth. Pereopod 2 (Figure 3D) ischium short; merus with rounded projection on lower proximal angle, with mesial row of setae; carpus broad distally; propodus upper and lower margins with row of setae; dactylus upper margin with row of setae, cutting edge of fingers both with 5 sharp spines (Figure 3E). Pereopod 3 (Figure 3F) ischium about 0.3 length of merus; merus 4 times as long as wide; carpus lower margin convex, broad distally; propodus ovate nearly 1.3 times as long as wide; dactylus elongate, 3.5 times as long as wide, acute at tip (Figure 3G). Pereopods 4 and 5 missing.
Male pleopod 1 (Figure 3I) uniramous, 2-articled, article 2 shorter than first, apically bifid.
Male pleopod 2 missing.
Pleopods 3–5 (Figure 3H). biramous, foliaceous, endopod wider than exopod, with a slender appendix interna.
Etymology. The species is named for its type locality, Qeshm Island.
Remarks. Placement of the new species in Gourretia follows Manning & Felder (Reference Manning and Felder1991), Tudge et al. (Reference Tudge, Poore and Lemaitre2000) and Sakai (Reference Sakai2011). Sakai's (Reference Sakai2011) key to species would take the new species close to G. manihinae Sakai, 1984 from Tanzania but the species also resembles the more recently described G. sinica Liu & Liu, Reference Liu and Liu2010 from the South China Sea. However it differs from both in the shapes of maxilliped 3, major and minor chelipeds, pereopod 2, uropodal exopod and telson. It should be noted that differences in spine number and size may change with size of the individual, aged and sexual maturity specimens as Liu & Liu (Reference Liu and Liu2010) mentioned and illustrated in their work. The maxilliped 3 ischium bears a projection at the rectangular proximal inner angle (vs strong tooth in G. sinica and G. manihinae), and its crista dentata has 8 strong and sharp spines (vs 14 small spines in G. sinica). The telson of G. qeshmensis is shorter than in G. manihinae and in G. sinica. The three species appear to differ in the armature of the uropodal exopod. In G. qeshmensis the posterior margin is armed with denticles and four strong spines while G. manihinae and G. sinica lack such denticles, although it is likely that these spines were not illustrated by the authors of the earlier species. The large cheliped has six ischial spines in G. qeshmensis, four in G. manihinae and five in G. sinica. The cutting edge of the fixed finger has six teeth in G. qeshmensis whereas G. sinica and G. manihinae have two teeth. Another diagnostic character of G. qeshmensis is seven teeth on the lower margin of the ischium of the small cheliped (vs five teeth in G. sinica and four teeth in G. manihinae). In addition, the number of spines on the fixed finger and dactylus of pereopod 2 in G. qeshmensis (five on each margin) differentiates G. sinica (with four) and G. manihinae (unarmed).
ACKNOWLEDGEMENTS
We thank Gary C.B. Poore (Museum Victoria) for critically reading drafts of the manuscript and for offering valuable comments and suggestions for improvements. Thanks are also due to Dr Peter Dworschak, Dr Alireza Sari and Dr Katsushi Sakai for their help.
