2 Results

2.1 Systematics

Superfamily: Majoidea Samouelle, 1819

Family: EPIALTIDAE MacLeay, 1838

Subfamily: PISINAE Dana, 1851 (Figure 2A; Figure 2B)

Hyastenus hilgendorfi (De Man, 1887)

2.2 Material examined

1 male, CL=31.5 x CW=18.2 mm, 1 female CL=27.6 x CW=14.8 mm (MSC).

Rass Al-Beshaa region, NW-arabian, Sta. 1, 7-10 m, 2 specimens. 1/11/2016.

1 male, CL=33.5 x CW=19.8 mm, 1 female CL= 25.3 x CW=13.4 mm (MSC).

Rass Al-Beshaa region, NW-arabian, Sta. 2, 10-15 m, 1 specimens. 28/11/2016.

2.3 Diagnosis

Carpace pear-shaped or sub-piriform, dorsal surface convex, slightly tuberculate, covered with a thin coating of setae. Rostral spines slender, divergent, horizontal and acuminate. Supraorbital eave developed, long, margin somewhat upturned, preorbital angle developed into a short forward directed spine, antorbital angle obtuse. Six mesobranchial tubercules sub-equal to the sides of the median line. Two divergent, slender rostral spines, of length equal to two thirds of the carapace length in males, much smaller in females. Eye pedicels short, retracting. Protogastric region with a very faint to distinct tubercle, if present. Mesogastric and cardiac region either smooth or with a low median tubercle each, both regions separated by a depressed urogastric region. Intestinal region with small curved spine, very close to posterior margin. Branchial region smooth or with two to three tubercles. Epibranchial teeth small, tuberculate to moderately long, curved apically. Basal antennal article with anterolateral angle produced into a finger-like projection, visible from dorsal view, lateral margin straight, proximal lobe broad, convex. Suborbital hiatus a very broad U shape.

The chelipeds are the same length as the carapace, the merus has nodules in its proximal portion while the claw is smooth and glabrous. The merus of the pereopods also bear nodules, while the posterior border of the dactyl is spiny, the spines becoming successively larger distally. The separation of the rostral spines is u shaped or keyhole shaped. Pterygostomial region with three large teeth, posteriormost directly above cheliped. Male and female abdomen with seven free segments.

2.4 Remarks

Specimens of H. hilgendorfi were described from the Shores of east Mediterranean by Galil (2006), This specimens agree closely with specimens description in current study from the Rass Al-Beshaa region, NW-Arabian Gulf.

Apel (2001) compared specimens H. hilgendorfi from the Persian Gulf with specimens from the Red Sea – and the specimens collected from these two regions were found to be similar in descriptions, While the specimens of H. pleione from Pakistan significantly different. The carapace is much less sculpted by H. hilgendorfi as in H. pleione. In any case, there are two distinct species, their distributions do not overlap.

H. hilgendorfi is a typical subtidal crab occurring rarely in low-intertidal zone. This species is a very common spider crab in the Persian Gulf (Naderloo and Sari, 2007a). There are four species of the genus Hyastenus known from the Persian Gulf (Naderloo and Sari, 2007b) but only H. hilgendorfi is considered as an intertidal element.

Colour: H. holgendorfi is a brownish colour.

2.5 Distribution

Distribution of Persian Gulf: Iran (Stephensen, 1946; Apel, 2001; Naderloo and Sari, 2007; Naderloo and Türkay, 2010), Kuwit (Apel, 2001), Saudi Arabia (Basson et al., 1977; Apel (2001), Bahrain (Stephensen, 1946), UAE (Nobili, 1906), Iraq (current study).

World Distribution: East African coast, Red Sea, Mediterranean Sea, Persian Arabian Gulf, Andaman Sea, Thailand, Indonesia, Philippines, Australia, Hawaii.

Habitat: intertidal and subtidal zones to 35m, substrates sandy and rocky.

3 Discussion

The Arabian Gulf (Persian Gulf) fauna is influenced by its specific environmental conditions, and is very poor compared to the Indian Ocean. The population of brachyuran crabs in the Persian Gulf is an exception to the greater variety of proportions It has other animal species and is comparable to the ocean. About 1000 species of crabs are from the western Indian Ocean (Apel, 2001).

The first finding of current specimens from invasive species H. holgendorfi in intertidal and subtidal areas of Iraqi coast in south al- Faw city, since the species is widely distributed in another parts of worldwide, especially in south part of Arabian Gulf and Oman Gulf (Apel, 2001; Stephensen, 1946), and due to the fact that this species can easily distributed by several reasons. One more reason, the ecological conditions and habitats in different areas in Arabian Gulf is similar to that of the Iraqi coast, southern Iraq. The present record to adds crab H. holgendorfi to the brachyura list of Iraqi waters.

Authors’ contributions

All authors in this paper have contributed equally toward the publication of this paper.

Acknowledgments

We thank Dr. Ghazi M. Al-Maliki, Marine biology department, Marine Sciences Center, Basrah University for reading the Manuscript and giving suggestions.

References

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