Introduction

The southern marsh area of Iraq is a huge aquatic habitat and is considered the centre of flourishing for all sorts of creatures including human being for the last 8,000 years (Heyvaert and Baeteman, 2008). These wetlands have confronted an intentional devastation by Sadam regime during the 1990s and the significant decrease of the natural wetland resources as a result of diverting Euphrates River so it will not feed the marsh area (Maltby, 1994; Partow, 2001). In 2003, the marsh area was re-flooded by the locals in order to let the water onto the past status (Richardson et al., 2005).

Mesopotamia or the land between two rivers is located north-east of the Arabian Peninsula at the edge of Zagros Mountains (Guest and Al-Rawi, 1966). It is included in the Saharo-Arabian region (Zohary, 1973). The location of the marshes in the lower reaches of the Tigris-Euphrates Rivers (30.5° to 32.5°N, 44° to 48°E). The marshes of Iraq fall into three parts according to its geographic position. Hammar Marshes are the marshes that found south of the Euphrates River, while Huwaiza Marshes are located to the east of the Tigris River. The Central marshes are those wetlands that lie between the two rivers.

Among the largest families in Teleosts fishes is the Family Gobiidae. There are 1763 valid species belonging to 170 genera (Eschmeyer and Fong, 2015). The members of this family are distributed in different habitats around the world (Thacker and Roje, 2011). The genus Acentrogobius contains five species: Acentrogobius: Acentrogobius viridipunctatus, Acentrogobius dayi, Acentrogobius decaryi, Acentrogobius simplex and Acentrogobius therezieni (Larson and Wright, 2003).

The presence of A. dayi in the new habitat, marshes of southern Iraq, is reported in this study. Previously, this species has been recorded from Sawa Lake, south west of Baghdad (Ziyadi et al., 2015). Therefore, the present record is the 2^nd in the inland waters of Iraq.

1 Material and Methods

On 7th June 2016, one specimen of day’s goby A. dayi (108 mm, TL) was collected from the southern marshes of Iraq near Al-Fuhud Village, Thiqar, Iraq (Figure 1) (30° 58′ 54.31″ N, 46° 46′ 35.18″ E) (Figure 2). Fish specimen was collected using cast net. Morphometric and meristic details were recorded and data are presented in Table 1. For taxonomic verification and precision of the spelling of species name, Eschmeyer (2014) and Fricke (2014) were used respectively. The specimens were stored in the fish collection of the Marine Science Centre, University of Basrah, Iraq.

Figure 3 Acentrogobius dayi, TL 108 mm, collected from the marsh near Al- Fuhud Village, Thiqar, Iraq.

2 Results

Head large and body elongated. Mouth directed upward. Gill opens extending midpoint of the orbit. Villiform teeth are on jaws. Caudal fin is round and shorter than head. Angle of the mouth is with two rows of papillae. First dorsal fin originated near the posterior end of the pectoral fin, while the 2^nd dorsal fin originated anterior to that of the anal fin. Ctenoid and cycloid scales are on posterior and anterior parts of the body respectively. No scales on head and operculum with embedded scales. Body greys in color. Lower sides and back of eyes are with dark brown bands. Body is with pale and blue-green spots. Upper angle of caudal fin base is with black spot (Figure 3). Morphometric and meristic data are given in Table 1.

3 Discussion

Randall (1995) and Froese and Pauly (2016) suggested that the maximum length of this species is 110 mm in total length. The total length of our specimen (108 mm) is fall near the upper limit of the reported for this species. It is smaller than that obtained for Sawa Lake specimen (Ziyadi et al., 2015) and also smaller than that given by Ghanbarifardi and Malek (2007) from the Arabian Gulf coasts of Iran (109 mm TL). It is larger than that given by Rahimian & Pehpuri (2006) (70 mm TL). In its description, the present specimens agrees with that given by Mutsaddi and Bal (1974), Randall (1995), Rahimain and Pehpuri (2006) and Ghanbarifardi and Malek (2007). Acentrogobius dayi is the only species of this genus is present in this part of the world (Froese and Pauly, 2016).

Acentrogobius dayi is recorded from several localities in the Western Indian Ocean, from the Arabian Gulf to Pakistan (Froese and Pauly, 2016), and the Mumbai region of India (Mutsaddi and Bal, 1974). Within the Arabian Gulf area, it is known from Kuwait (Randall, 1995; Bishop, 2003), Saudi Arabia and Pakistan (Randall, 1995). Coad (1991) reported the presence of Acentrogobius dayi from Basrah, but it was originally recorded by Koumans (1941) from Fao, south of Iraq.

Water of the southern marshes of Iraq originates from both Tigris and Euphrates Rivers and that of the marshes near Thiqar province has Euphrates River origin. Shatt al-Basrah canal is a water way that connects the greater marsh area with the north-west corner of the Arabian Gulf. Through this canal, marine fish species gained entrance to the southern marsh area and might reach localities away from their marine environment further north into Mesopotamia (Coad, 2010; Jawad, 2012). Fishermen operating at Shatt al-Basrah Canal also fish at the southern reaches of the marshes and commune between the two regions daily. During their fishing operations, they use the same fishing gears. Such practice might act as a transport agency for eggs and larvae that might survive in the damp areas of the fishing gear the short journey from Shatt al-Basrah Canal to the marsh area which is about 5Km (Jawad, 2006). This type of transfer which aid invasion has been documented in several countries such as in Australia (Linterman, 2004), which gives a potential for the transfer of eggs on nets. In New Zealand, fishes were found to spawn on fishing nets (McDowall, 1996). Therefore, it is very important to make sure that the fishing nets are clean before using it in another water body.

Absence of efficient ichthyological survey may hinder the appearance of Acentrogobius dayi from the marsh area. Previously, inappropriate fishing gear and less geographical areas surveyed might be behind the appearance of this species in the area. With the widening the investigation area due to research programs helps in recording several invasive species both marine and freshwater (Coad, 2009; Mohamed et al., 2009; Al-Faisal and Mutlak, 2014). Also, the use of appropriate fish sampling methodologies such as electric fishing (Al-Dubaikel, 2011) has already repudiated the presumed rarity of several species in other water bodies within the area (Jawad et al., 2010; Ziyadi et al., 2015). Indeed, the present record of Acentrogobius dayi from the marsh area represents a significant contribution to the study of zoogeographical patterns within this area of Iraq.

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