Article. Discovery of Metacrangonyx in inland groundwaters of Oman (Amphipoda: Gammaridea: Metacrangonyctidae)

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1 Zootaxa 3335: (2012) Copyright 2012 Magnolia Press Article ISSN (print edition) ZOOTAXA ISSN (online edition) Discovery of Metacrangonyx in inland groundwaters of Oman (Amphipoda: Gammaridea: Metacrangonyctidae) DAMIÀ JAUME 1 & RONALD VONK 2 1 IMEDEA (CSIC-UIB), Instituto Mediterráneo de Estudios Avanzados, C/ Miquel Marquès 21, Esporles, Balearic Islands, Spain. damiajaume@imedea.uib-csic.es 2 Netherlands Centre for Biodiversity Naturalis, Darwinweg 2, 2333 CR Leiden, The Netherlands. ronald.vonk@ncbnaturalis.nl Abstract A new species of metacrangonyctid amphipod crustacean is described from the Salalah coastal plain aquifer in south-western Oman. This is the easternmost record of the group, with representatives previously thought to span from Hispaniola in the Caribbean to the Sinai Peninsula in Egypt. Metacrangonyx dhofarensis sp. nov. is unique among metacrangonyctids in the display of a sexually dimorphic armature on pereiopod IV. In addition, its hypertrophied coxal plate IV, reduced plates I-III, coxal plate VII lacking anteroventral lobe, and telson longer than broad are also distinctive. The same holds for the proximal segment of peduncle of antennule, provided with two hypertrophied robust setae on dorsolateral margin. The mandibles of the new species are devoid of palp, a feature shared only with Metacrangonyx antennatus Messouli, El Alami, Coineau & Boutin, The presence of metacrangonyctids on the coasts of the Arabian Peninsula is probably the result of a vicariant event rather than of an episode of trans-arabian continental dispersal by a Middle East ancestor. This is in accord with the presumed marine origin of the family and with the existence of a shallow water marine continuum between the current south-western Omani coast and the peri-mediterranean area where most species of metacrangonyctids are located until approximately 16 Ma. Key words: Gammaridea, Metacrangonyctidae, stygofauna, subterranean waters, Arabian Peninsula Introduction Metacrangonyctids are a small group of exclusively stygobiont amphipods comprising 19 described species distributed in two genera, Metacrangonyx Chevreux, 1909, and the monotypic Longipodacrangonyx maroccanus Boutin & Messouli, They have a broad but punctuated distribution spanning Caribbean (Jaume & Christenson 2001), East Atlantic (Stock & Rondé-Broekhuizen 1986) and western Mediterranean islands (Chevreux 1909; Stoch 1997), but also continental territories such as the Dead Sea Depression and the Sinai Peninsula in the Middle East (Karaman 1989; Ruffo 1982), plus Morocco. In the latter country, with many species still pending description, they show a generalised distribution except on the Mediterranean coast (Balazuc & Ruffo 1953; Boutin & Messouli 1988a; 1988b; Karaman & Pesce 1980; Messouli et al. 1991; 2008; Oulbaz et al. 1998; Ruffo 1954). Habitat preferences of metacrangonyctids are broad and cover anchialine caves and wells placed in coastal areas, hyporheic layers and associated alluvial aquifers in floodplains, and even springs and hypotelminorheic biotopes high up to 1,800 m a.s.l. in the High Atlas mountains. The family is considered to be of marine origin and its penetration into inland ground waters to be a passive, recurrent process mediated by past marine regressions (Boutin 1994). Here we describe a new member of the family from two wells located in the south-west of the Sultanate of Oman (Arabic Peninsula) (Fig. 1). The material was originally collected by the late Prof. Jan H. Stock in the Salalah coastal plain (Dhofar Governorate) during a joint biological ground water survey by the Zoological Museum of the University of Amsterdam and the Oman Research Department of the Ministry of Regional Municipalities & Water Resources (Stock et al. 1997). In earlier years, several new stygobiont amphipods from this expedition throughout the north-east and south-east of the Sultanate have been described (Ruffo et al. 2003; Iannilli et al. 54 Accepted by J. Lowry: 10 Apr. 2012; published: 6 Jun. 2012

2 2006; Vonk and Jaume 2010). Metacrangonyx dhofarensis sp. nov., described herein, represents the easternmost record of the genus, and extends the range of occurrence of the family from Hispaniola in the Caribbean, throughout the Mediterranean, to the Indian Ocean shores of the Arabian peninsula. The Salalah plain is underlain by a shallow limestone aquifer that is historically the only natural source of water supply for the human population (Shammas 2007). After 2005 the pumping rate is on average more than the recharge rate and seawater intrusion has been reported (Shammas 2002; 2007). This is disturbing the normal fluctuation in salinity and possibly is affecting stygofauna adapted to gradual seasonal cycles. FIGURE 1. Map of Oman showing the location of the type locality of Metacrangonyx dhofarensis sp. nov. NEW METACRANGONYCTID AMPHIPOD FROM OMAN Zootaxa Magnolia Press 55

3 Material and methods Specimens were taken with a Cvetkov net (see Bou 1974), fixed in the field in formalin and transferred to 70 % ethanol once in the laboratory. Before study, specimens were treated with lactic acid to soften the cuticle and remove internal tissues to facilitate observation. Drawings were prepared using a camera lucida on Olympus BH2 and Leica DM 2500 microscopes equipped with Nomarski differential interference contrast. Material preserved on slides was mounted in lactophenol and the cover-slips sealed with nail varnish. Body measurements were derived from the sum of the maximum dorsal dimensions (including telescoped portions) of head, pereionites, pleosomites and urosomites, and exclude telson length. Material is deposited in the Crustacea collection of the Netherlands Centre for Biodiversity Naturalis (NCB Naturalis) in Leiden, The Netherlands. Following Watling (1989), the term "spine" in descriptions is reserved for rigid armature elements with a hollow central core that do not articulate basally to the body integument. Gnathopods I and II, and pereiopods III to VII appear abbreviated elsewhere as G1 G2 and P3 P7, respectively; uropods I III, as U1 U3. Taxonomy Order AMPHIPODA Latreille, 1816 Suborder GAMMARIDEA Latreille, 1802 Family Metacrangonyctidae Boutin & Messouli, 1988 Genus Metacrangonyx Chevreux 1909 Metacrangonyx dhofarensis sp. nov. (Figs 2 10) Material examined. Collected by Jan H. Stock and co-workers, 6 April Dahariz north, Salalah, Dhofar Governorate, Oman. Station B in Stock et al. (1997). Ministry of Water Resources well no. 202/304; closed, square, 1.5x1.5 m well with electric pump; water surface at 7.5 m, water column 0.5 m; UTM coordinates (Datum unknown) / (ca. 17º01 21 N 54º09 35 E). Holotype: preparatory female (oostegites developed, but non-setose) 4.37 mm; completely dissected and mounted on single slide [ZMA Amph ]. Paratypes: one preparatory female 4.36 mm; two males, 3.80 and 3.58 mm, one of them with G2 and P3&4 dissected and preserved on single slide; three juveniles, one of them possibly female [ZMA Amph ]. In addition, two preparatory females were also examined but were accidentally lost. Al Hafah, Salalah. Covered well in urban area, with electric pump. GPS coordinates (Datum WGS84): N º, E º. Water surface at 3 m, water column 0.3 m. 27 specimens, both sexes, preserved in ethanol vial. Collected by authors, 5 March Diagnosis. Metacrangonyctid with hypertrophied coxal plate IV and reduced plates I-III. Coxal plate VII lacking anteroventral lobe. Mandibular palp wanting. Proximal segment of peduncle of antennule provided with two hypertrophied robust setae on dorsolateral margin. Telson longer than broad. Sexual dimorphism manifested on presence of series of long simple setae on posterior margin of propodus of male pereiopod IV. Etymology. Species name refers to its area of distribution, apparently limited to the Dhofar Governorate in the Sultanate of Oman (SE Arabian Peninsula). Description of adult female. Body (Fig. 2) compact, with integument of somites and limbs densely covered with blunt setules (sketched only in some figures). Head with hardly developed lateral lobes; post-antennal sinus shallow, hardly noticeable. Epimeral plates (Fig. 9A) unarmed, each with pointed posteroventral corner; ventral margin of plate I straight, margins of plates II-III evenly convex; posterior margin of plate I convex, those of plates II-III straight. Antennule (Figs 2; 3A) peduncle segments non-elongated, progressively shorter towards distal; proximal segment provided with two long and stout robust setae on dorsolateral margin, distal seta attaining about half length of segment. Main flagellum longer than peduncle, up to 12-articulate, with one aesthetasc per article at most. Accessory flagellum 1-articulate, slightly overreaching distal margin of proximal article of main flagellum. 56 Zootaxa Magnolia Press JAUME & VONK

4 Antenna (Figs 2; 3B) gland cone slender, slightly overreaching distal margin of third peduncle segment; medial surface of latter segment with triangular outgrowth provided with two setae; peduncle segments 4-5 progressively longer towards distal; segment 4 only 3.1 times longer than broad; segment times as long as segment 4. Flagellum short, up to 6-articulate, shorter than peduncle segments 4-5 combined. FIGURE 2. Metacrangonyx dhofarensis sp. nov., habitus of female paratype 4.36 mm. Labrum (Fig. 4A) globose, ordinary. Paragnaths (Fig. 4B) with no trace of inner lobes. Mandibles devoid of palp. Left mandible (Fig. 4C, D) with 6-denticulate incisor and 5-denticulate lacinia; spine row composed of 5 stout denticulated elements; row of 5 long spinulose setules running subparallel to spine row as figured; row of 4 secretory pores placed adjacent to spine row as figured; molar triturative, columnar, with three short plumose setules implanted close to each other on distal margin; molar seta reduced. Right mandible (Fig. 4E) with 6-denticulate incisor and complex, bifid lacinia provided with marginal patch of setules; spine row composed of 4 elements plus row of only three spinulose setules; rest of appendage similar to left counterpart except for longer molar seta. NEW METACRANGONYCTID AMPHIPOD FROM OMAN Zootaxa Magnolia Press 57

5 FIGURE 3. Metacrangonyx dhofarensis sp. nov., holotype. A, left antennule, medial; B, left antenna, lateral. Maxillule (Fig. 5A) coxal endite with row of 10 short, plumose marginal setae. Basal endite with only 9 rakelike robust setae. Endopod 2-segmented, distal segment with 5 heterogeneous setae distally. Maxilla (Fig. 5B) inner lobe with row of 10 facial setae; distal half of medial margin with ca. 8 sparsely set, stiff setae with pointed tip; ca. 9 setae with blunt bifid tip placed terminally on lobe. Outer lobe with two rows of setae plus isolated, short simple seta distally; one of setae of distal row stouter than rest. 58 Zootaxa Magnolia Press JAUME & VONK

6 FIGURE 4. Metacrangonyx dhofarensis sp. nov., holotype. A, labrum, posterior; B, paragnaths, anterior; C, right mandible, posterior; D, detail of lacinia of latter; E, left mandible, posterior. Maxilliped (Fig. 5C) basal endite subrectangular with distolateral angle produced into pointed process; distal margin with 6 heterogeneous setae, one of which simple, another one pinnate, both with rounded tip; remaining 4 distal setae short, robust, blunt, flattened, one of which more slender than rest; submarginal row of 7 setae running subparallel to distal margin and distal half of medial margin of endite as figured. Ischial endite (Fig. 5D) expanded with 10 short robust setae along distal and distomedial margins, distolateral seta more slender than rest; three more distal robust setae denticulated. Rest of limb as figured. NEW METACRANGONYCTID AMPHIPOD FROM OMAN Zootaxa Magnolia Press 59

7 FIGURE 5. Metacrangonyx dhofarensis sp. nov., holotype. A, maxillule; B, maxilla; C, right maxilliped, anterior (coxa omitted); D, detail of ischial endite; E, inset of distal portion of palp, posterior. Pereiopodal coxal plates I-III reduced, much shorter and narrower not only than plate IV, but also than plates V-VI, and equalling plate VII in length (see Fig. 2). Plate IV broadly expanded, with deeply excavated posterior 60 Zootaxa Magnolia Press JAUME & VONK

8 FIGURE 6. Metacrangonyx dhofarensis sp. nov., holotype. A, left gnathopod I, medial; B, inset of hand, medial; C, right gnathopod II, medial; D, inset of distal part of propodus, medial; E, detail of nail, medial. NEW METACRANGONYCTID AMPHIPOD FROM OMAN Zootaxa Magnolia Press 61

9 FIGURE 7. Metacrangonyx dhofarensis sp. nov., holotype. A, right pereiopod III, medial; B, inset of nail; C, left pereiopod IV, medial; D, inset of nail. margin; plate adorned with submarginal row of simple setae (Fig. 7C). Plate V with well-developed, evenly rounded anteroventral lobe provided with simple seta (Fig. 8A). Anteroventral lobe on plate VI reduced, finger-like (Fig. 8C). Plate VII devoid of anteroventral lobe (Fig. 8E). Coxal gills present on G2 to P6, ellipsoid and stalked (Figs 6C; 7A, C; 8A, C). Oöstegites on G2 to P5, ordinary (Figs 6C; 7A, C; 8A). Gnathopod I (Fig. 6A) reduced compared to rest of pereiopods; all segments bearing patch of spinules on medial surface as figured. Carpus elongated, longer than propodus. Propodus (Fig. 6B) subrectangular, twice as long as broad; palm angle lined with only one medial and two lateral unicuspid flagellate robust setae; palm margin short, oblique, slightly convex with microspinulate surface. Gnathopod II (Fig. 6C) slender, with carpus elongated, longer than propodus; both segments with posterior 62 Zootaxa Magnolia Press JAUME & VONK

10 margin poorly armoured. Propodus not expanded, more slender than carpus, 2.8 times as long as broad with subparallel margins; two stout flagellate setae pointing outwards, one of them hypertrophied, implanted close to palm margin on outer (= lateral) surface of segment (Fig. 6C, D; also visible in Fig. 2); palm angle placed at 68% of maximum length of segment, marked by reduced flagellate unicuspid robust seta on medial side and similar but larger seta on lateral side (Fig. 6D); palm margin short, oblique, straight, with microspinulate integument and devoid of robust setae (Fig. 6D). Posterior margin of dactylus densely microspinulate (Fig. 6E). Pereiopods III & IV (Fig. 7) about equal in length, ordinary, each with unguis about two-thirds as long as corresponding dactylus. FIGURE 8. Metacrangonyx dhofarensis sp. nov., holotype. A, right pereiopod V, lateral; B, detail of nail; C, right pereiopod VI, lateral; D, detail of nail; E, detail of pereiopod VII, lateral; F, detail of nail. Pereiopods V-VII (Fig. 8) each with broadly expanded basis with strongly overhanging posterodistal angle. Basis of P5 with anterior and posterior margins strongly convex conferring segment subcircular aspect. P5 and P7 subequal in length, P6 longest. Nails of P5-P6 subequal in length, nail of P7 shorter; each with dactylus ca. 2.5 NEW METACRANGONYCTID AMPHIPOD FROM OMAN Zootaxa Magnolia Press 63

11 times as long as corresponding unguis (compare Fig. 8B, D and F). Marginal armature of robust setae on pereiopods variable in number (cf. Fig. 2). Pleopods (Fig. 9B) biramous, protopods devoid of marginal setae, each with two retinacles. Proximal seta on inner margin of proximal article of endopod modified, shorter than rest, with smooth, bifid distal portion. FIGURE 9. Metacrangonyx dhofarensis sp. nov., holotype. A, right epimeral plates, lateral; B, right pleopod I, posterior; C, inset of urosome, lateral; D, right uropod I, posterior; E, right uropod II, posterior; F, left uropod III, posterior; G, telson, posterior (= dorsal). 64 Zootaxa Magnolia Press JAUME & VONK

12 FIGURE 10. Metacrangonyx dhofarensis sp. nov., male paratype 3.80 mm. A, left pereiopod IV showing setose posterior margin of carpus and propodus, medial; B, right gnathopod II, medial, hand omitted; C, inset of hand of latter, medial. Uropods progressively shorter towards posterior, tip of U1 reaching tip of U2 (Fig. 9C). Uropod I (Figs 9D; 2) with exopod much shorter than endopod, both rami shorter than protopod. Latter with one flagellate robust seta at each posterodistal corner plus two flagellate robust setae on lateral and medial margins. Exopod devoid of marginal NEW METACRANGONYCTID AMPHIPOD FROM OMAN Zootaxa Magnolia Press 65

13 armature, with 4 unequal robust setae terminally, two of which reduced. Endopod with 2-3 robust setae along medial margin; tip of segment with 5 flagellate robust setae, two of which reduced, plus reduced smooth seta. Uropod II (Figs 9E; 2) with exopod much shorter than both endopod and protopod; exopod longer than protopod. Protopod with one flagellate robust seta at each posterodistal corner plus another one about midway of lateral margin. Terminal armature of rami as in U1 except for absence of reduced smooth seta on endopod tip. Endopod with 0-2 flagellate robust setae along lateral margin. Exopod with 0-1 flagellate robust seta along lateral margin and 2-3 flagellate robust setae along medial margin. Uropod III (Fig. 9F) uniramous with no trace of endopod; exopod longer than protopod. Protopod with simple seta midway of inner margin. Exopod lanceolate, with two flagellate (only 1 in smaller specimens) robust setae along inner margin and flagellate robust seta on tip. Telson (Fig. 9G) triangular, about 1.2 times longer than broad, with two simple and two penicillate setae subterminally on dorsal surface, and one lateral penicillate seta at each side. Description of male. Males are apparently smaller than females and show a modified setation (long setae vs. short setae in female) on the posterior margin of carpus and propodus of P4 (Fig. 10C). The gnathopod II palm (Fig. 10A, B) is rhomboidal, with the palm angle placed at about 32% length of segment; the palm margin is smooth, undulate, and lined by a series of 10 smooth, unicuspid strong robust setae on outer side, and a series of approximately 10 short simple setae with blunt tip on medial side; there is one short bifid robust seta close to palm angle on medial surface of segment, and two long flagellate setae pointing outwards implanted nearby on outer (= lateral) surface; the posterior margin of palm is short and unarmed. Discussion The new taxon from Oman displays the typical features of metacrangonyctids, i. e. a short, piriform uropod III with reduced rami; an entire, non-excavated telson; the combination of a gnathopod I of melitoid type (i.e. much smaller than gnathopod II, with an elongate carpus, and with propodus subrectangular with transverse or scarcely oblique palm margin) and a gnathopod II of hadzioid type (i.e. with variably elongate carpus, and with palm margin of propodus almost indistinct from posterior margin of segment); paragnaths lacking inner lobes; variably regressed mandibular palp; and inner lobe of maxilla provided with oblique row of facial setae (see Boutin & Messouli 1988b). Nevertheless, it shows a series of traits not reported before in this otherwise morphologically homogeneous family. Thus, the sexually dimorphic pereiopod IV contrasts with the condition found in other metacrangonyctids, where sexual dimorphism manifests at most in the morphology of gnathopod II and the length of the antennule. The reduced coxal plates I-III, and the broadly expanded plate IV of the new species differ from the rest of metacrangonyctids, where the length of these four coxal plates is comparatively similar. The coxal plate VII is also unique in the lack of anteroventral lobe; the remaining metacrangonyctids display this lobe expressed to a variable extent. Another noteworthy feature of the new taxon pertains to the two strong flagellate robust setae implanted dorsolaterally on the first peduncle segment of the antennule; no other metacrangonyctid displays hypertrophied robust setae on this segment, or robust setae on such a position. The telson of the new species is also remarkable in being longer than broad; other metacrangonyctids (with the exception of M. longicaudus Ruffo, 1954, of which the telson was not described) display a telson broader than long. Finally, the new species is, together with the recently described M. antennatus Messouli, El Alami, Coineau & Boutin, 2008, the only metacrangonyctid devoid of mandibular palp. Other relevant features of the new taxon compared to the rest of metacrangonyctids are shown in Table I. Boutin (1994) and co-workers have presented an intra-family phylogeny of the Metacrangonyctidae based mainly on the morphology and armature arrangement of the third uropod, where four lineages are clearly depicted. Accordingly, the new species from Oman would belong to the so-called spinicaudatus-group, mainly characterised by the presence of marginal armature on the uropod III exopod. We will not go further here on the relationships of the new taxon since molecular phylogenetic analyses underway show little correspondence between the former clades and those arising from DNA sequences. The presence of metacrangonyctids on the coasts of the Arabian Peninsula is probably the result of a vicariant event rather than of an episode of trans-arabian continental dispersal by a Middle East ancestor. This is in accord with the presumed marine origin of the family and with the existence of a shallow water marine continuum 66 Zootaxa Magnolia Press JAUME & VONK

14 between the current south-western Omani coast and the peri-mediterranean area where most species of metacrangonyctids are located until approximately 16 Ma (Meulenkamp & Sissingh 2003). TABLE 1. Main distinctive features of the species of Metacrangonyx and of Longipodacrangonyx maroccanus. (+: present; -: absent) M. dhofarensis M. antennatus M. aroudanensis M. delamarei M. dominicanus M. gineti M. goulmimensis M. ilvanus M. knidirii M. longicaudus M. longipes M. ortali M. panousei M. remyi M. repens M. ruffoi M. samanensis M. sinaicus U3 endopod U3, [exopod : protopod] length >1 <1 <1 =1 =1 <1 <1 <1 <1 >1 <1 <<1 =1 <1 <1 <1 >1 <<1 >1 <1 U3 exopod marginal armature U3 exopod, no. terminal robust setae 1 > >1 1 >1 1 1 > U1, basofacial robust seta - + +? ? U1 endopod, anterior slender seta Telson, robust setae ? - - -? G2, [carpus : propodus] length <1??? =1 <1?? <1? <<1 <1 <1 <1 <<1?? <<1 <1? G2, [carpus : propodus] length >1 <1?? =1 <1? <1 <1? <1 =1 <1 <1 <<1? >1 <1 =1 <1 G2, palm margin (Str: straight / Con: concave / Cvx: convex) Str Con?? Str Cvx? Str Str? Con Str Cvx Con Cvx? Str Str Cvx Con Md palp, no. segments (2) A1, accessory (2) flagellum, no. articles M. spinicaudatus L. maroccanus Acknowledgements This is a contribution to Spanish MICINN project CGL , in part co-financed with EU FEDER funds. The Research Department of the Ministry of Regional Municipalities and Water Resources, Ruwi, Oman is thanked for the substantial financial, personnel, and logistic support given to Jan Stock and Jan Vermeulen during the survey in the spring of Sampling performed in 2012 by authors could not have been possible without the support and facilities provided by Mr. Dr. Zaher Khaled al Suleimani, Dr. Abdullah Bawain and Mr. Ali Bait Said, of the Ministry of Regional Municipalities and Water Resources. References Balazuc, J. & Ruffo, S. (1953) Due nuove specie del genere Metacrangonyx Chevreux (Amphipoda - Gammaridae) delle aque interne del Nord Africa francese. Memorie del Museo Civico di Storia Naturale di Verona, 4, Bou, C. (1974) Les méthodes de récolte dans les eaux souterraines interstitielles. Annales de Spéologie, 29, Boutin, C. (1994) Phylogeny and biogeography of metacrangonyctid amphipods in north Africa. Hydrobiologia, 287, Boutin, C. & Messouli, M. (1988a) Metacrangonyx gineti n. sp. d une source du Haut-Atlas marocain et la famille des Metacrangonyctidae n. fam. (crustacés amphipodes stygobies). Vie et Milieu, 38, Boutin, C. & Messouli, M. (1988b) Longipodacrangonyx maroccanus n. gen., n. sp., nouveau representant du groupe Metacrangonyx dans les eaux souterraines du Maroc. Crustaceana, Supplement 13, Boutin, C. & Messouli, M. & Coineau, N. (1988) Phylogénie et biogéographie évolutive d un groupe de Metacrangonyctidae, crustacés amphipodes stygobies du Maroc. II - Cladistique et paléobiogéographie. Stygologia, 7, Chevreux, E. (1909) Biospeologica XII. Amphipodes (Première Série). Archives de Zoologie Expérimentale et Générale, 5 e Série, Tome II, Iannilli, V., Holsinger, J.R., Ruffo, S. & Vonk, R. (2006) Two new genera and two new species of the subterranean family Bogidiellidae (Crustacea, Amphipoda) from groundwaters in northern Oman, with notes on the geographic distribution of the family. Zootaxa, 1208, Jaume, D. & Christenson, K. (2001) Amphi-Atlantic distribution of the subterranean amphipod family Metacrangonyctidae (Crustacea, Gammaridea). Contributions to Zoology, 70, Karaman, G.S. (1989) Metacrangonyx ortali, n. sp., a new subterranean member of the family Crangonyctidae from Dead Sea region. Studia Marina, 20, NEW METACRANGONYCTID AMPHIPOD FROM OMAN Zootaxa Magnolia Press 67

15 Karaman, G.S. & Pesce, G.L. (1980) Researches in Africa by the Zoological Institute of L Aquila, Italy. V. On three subterranean amphipods from North Africa (Amphipoda: Gammaridea). Bulletin Zoologisch Museum Universiteit van Amsterdam, 7, Messouli, M., Boutin, C. & Coineau, N. (1991) Phylogénie et biogéographie évolutive d un groupe de Metacrangonyctidae, crustacés amphipodes stygobies du Maroc. I - Les espèces du groupe panousei. Mémoires de Biospéologie, 18, Messouli, M., El Alami, F., Coineau, N. & Boutin, C. (2008) Metacrangonyx antennatus, a new species of the family Metacrangonyctidae (Crustacea, Amphipoda) from ground waters in south-western Morocco. Subterranean Biology, 6, Meulenkamp, J.E. & Sissingh, W. (2003) Tertiary palaeogeography and tectonostratigraphic evolution of the Northern and Southern Peri-Tethys platforms and the intermediate domains of the African-Eurasian convergent plate boundary zone. Palaeogeography, Palaeoclimatology, Palaeoecology, 196, Oulbaz, Z., Messouli, M., Coineau, N. & Boutin, C. (1998) Metacrangonyx knidirii n. sp. et Metacrangonyx remyi Balazuc et Ruffo, 1953 (crustacés amphipodes Metacrangonyctidae) des eaux souterraines du Maroc. Mémoires de Biospéologie, 25, Ruffo, S. (1954) Metacrangonyx longicaudus n. sp. (Amphipoda Gammaridae) delle acque sotterranee del Sahara marocchino. Memorie del Museo Civico di Storia Naturale di Verona, 4, Ruffo, S. (1982) Une nouvelle espèce de Metacrangonyx Chevreux (Amphipoda: Gammaridae) du Desert du Sinai. Israel Journal of Zoology, 31, Ruffo, S., Holsinger, J.R. & Sawicki, T.R. (2003) Indoweckelia stocki n. sp. from subterranean waters of Northern Oman: the second weckeliid amphipod crustacean (Hadziidae) described from the Middle East. Bollettino del Museo Civico di Storia Naturale di Verona, 27, Botanica Zoologia, Shammas, M.I Seawater intrusion in the Salalah aquifer, Sultanate of Oman. In: Sherif, M., Singh V.P., Al-Rashed M. (Eds), Proceedings of the International Conference on Water Resources Management in Arid Regions, Warmar, 2002 March 23-27, Kuwait. Vol. 3. Environment and Groundwater Pollution. A.A. Balkema, The Netherlands, pp, Shammas, M.I Sustainable management of the Salalah coastal aquifer in Oman using an integrated approach. Doctoral Thesis, Department of Land and Water Resources Engineering, Royal Institute of Technology (KTH), Stockholm, Sweden, 34 pp. Stoch, F. (1997) Metacrangonyx ilvanus n. sp., the first Italian representative of the family Metacrangonyctidae (Crustacea: Amphipoda). Annales de Limnologie, 33, Stock, J.H., Rondé-Broekhuizen, B.L.M. (1986) A new species of Pygocrangonyx, an amphipod genus with African affinities, from Fuerteventura. Bijdragen tot de Dierkunde, 56, Stock, J.H., Vermeulen, J.J. & Al Nofli, A.M. (1997) Research Program: Biological Ground Water Survey of the Sultanate of Oman. List of Sampling Stations March-April Verslagen En Technische Gegeven, Instituut voor Systematiek en Populatie biologie (Zoölogisch Museum), Universiteit van Amsterdam, 71, Vonk, R. & Jaume, D. (2010) Glyptogidiella omanica gen. et sp. nov., an inland groundwater bogidiellid from Oman with enlarged coxal plate V (Crustacea, Amphipoda). Zootaxa, 2657, Watling, L. (1989) A classification system for crustacean setae based on the homology concept. In: Felgenhauer, B., Watling, L. & Thistle, A.B. (eds.), Functional morphology of feeding and grooming in Crustacea. A. A. Balkema, Rotterdam, pp Zootaxa Magnolia Press JAUME & VONK