Aquatic Coleoptera from Pakistan: faunistic and zoogeographical contribution (Coleoptera: Gyrinidae: Dytiscidae: Hydrophilidae)

Abstract Records of 19 species and one subspecies of water beetles of four families: Gyrinidae (two species), Dytiscidae (seven species), Hydrophilidae (10 species), and Spercheidae (one subspecies) from Pakistan are listed, based on collected material. Four genera and 10 species are recorded from Pakistan for the first time. The newly recorded genera are: Patrus, Helochares, Sternolophus and Coelostoma. The newly recorded species are: Dineutus spinosus (Fabricius, 1781), Patrus haemorrhous (Régimbart, 1891), Copelatus freudei Guignot, 1955, Copelatus sp1, Copelatus sp2, Enochrus ater (Kuwert, 1888), Helochares anchoralis Sharp, 1890, Sternolophus rufipes (Fabricius, 1792), Paracymus aeneus (Germar, 1824) and Coelostoma stultum (Walker, 1858). Zoogeographic affinities of the recorded species are discussed. According to their current distribution, the 18 species known from Pakistan can be classified into five zoogeographical categories.


Introduction
Zoogeographically, the major part of Pakistan is in the Palaearctic Region (Hindu Kush, Karakorum, western Himalayas, Sulaiman Range, North Pakistan sandy desert and western Indus Valley) whilst the rest of the area is in the Oriental Region (Indus River Delta, eastern Indus Valley desert, Thar desert, Rann of Kutch in southern Punjab and eastern Himalaya) and traces of the Afrotropical Region from southern Iran to extreme southwestern Baluchistan. The Hindu Kush, Karakorum and Himalayas are a major biogeographic boundary between the subtropical and tropical flora and fauna of the Indian subcontinent and the temperate-climate Palaearctic Region (Rafi et al. 2010). Pakistan lies in the temperate zone. The climate is generally arid, characterised by hot summers and cool or cold winters, and wide variations between extremes of temperature at given locations. There is little rainfall. These generalisations should not, however, obscure the distinct differences existing amongst particular locations (Blood 1994).
The distribution of aquatic Coleoptera is not well explored in Pakistan. Many scattered, but limited, studies have been carried out in the past. The aim of this paper is to document the newly recorded genera and species of aquatic beetles from Pakistan.

Material and methods
Specimens were collected using a small aquatic dip net with a triangular frame, various small metal kitchen sieves and a light trap. All specimens are deposited in the M.C. Darilmaz Collection (University of Aksaray, Turkey).
The nomenclature used is as follows: for Gyrinidae by Miller and Bergsten (2012); for Dytiscidae by Nilsson (2013); for Hydrophilidae and Spercheidae by Short and Fikáček (2013) and Hansen (2004).
Materials were collected for this study from the following localities ( Figure 1

Results
The following symbols are used in the text: *: New record at the species level; **: New record at the genus level.
Family GYRINIDAE Latreille So far only one species Dineutus indicus (Aubé) has been recorded from Pakistan (Mazzoldi 2003 (Brinck 1981). This subgenus is characterised by the epipleural (postero-lateral) angle of the elytra being produced into a distinct spine. In the Indomalayan Region this subgenus is represented by two species, Dineutus unidentatus Aubé and D. spinosus (Fabricius). The two species are easily distinguished by the yellow margin of the elytra of D. unidentatus, whilst D. spinosus is evenly dark and bronzed (Balke et al. 2004). In this study, D. spinosus is the first representative of the subgenus from Pakistan.

Distribution
An Indian species, so far the species has been recorded from Bihar, Karnataka, Madhya Pradesh, Maharashtra, Tamil Nadu and West Bengal (Vazirani 1984 Wewalka, 1979 (Ghosh andNilsson 2012). The latter species is recorded here also for Pakistan. However, Hydaticus leander (Rossi) was recorded from Pakistan by Darilmaz and Ahmed (2009). Afterwards, the first author rechecked this specimen and concluded the specimen belongs to Hydaticus ponticus Sharp.

Tribe ERETINI Crotch Genus Eretes Laporte
The genus Eretes was revised by Miller (2002). Four species are recognised in the genus; two of them Eretes griseus (Fabricius) and Eretes sticticus (Linnaeus) were recorded from Pakistan (Miller 2002). E. griseus is recorded here also for Pakistan.

Distribution
This species occurs from Indonesia, the extreme northern tip of Australia (Darwin) and Guam to Japan and the Philippines to the Sichuan province of China and Vladivostok, Russia throughout southern Asia and Africa, including Madagascar, and north to southern Europe (Miller 2002 So far, only one species has been recorded from Pakistan: Copelatus feae Régimbart (Ghosh and Nilsson 2012). In this study, three different species were recognised, however, as two species are represented only by single females; only one species (male) is identified to the species level.

Notes
Single male with broken apex of median lobe. However, based on habitus and shape of remaining part of median lobe, the specimen can be, with little hesitation, assigned to C. freudei, described from northern India (Bengal) and subsequently recorded also from Bhutan (Wewalka 1975 So far, only one species has been recorded from Pakistan: Enochrus esuriens (Walker) (Hansen 1999(Hansen , 2004. The species is recorded here also for Pakistan. Also, in this study, E. ater is the second representative of the genus from Pakistan.
Subfamily ACIDOCERINAE Zaitzev ** Genus Helochares Mulsant Until now, no species of this genus was known from Pakistan (Hansen 1999(Hansen , 2004. In this study, this genus of the Hydrophilidae is first represented in Pakistan.
Genus Regimbartia Zaitzev Only one species has been recorded from Pakistan: Regimbartia attenuata (Fabricius) (Hansen 1999(Hansen , 2004. The species is recorded here also for Pakistan.

Genus Hydrophilus Geoffroy
So far, one species has been recorded from Pakistan: Hydrophilus senegalensis (Percheron) (Hansen 1999(Hansen , 2004Darilmaz and Ahmed 2009). The species is recorded here also for Pakistan.
Tribe LACCOBIINI Bertrand Genus Paracymus Thomson So far, one species has been recorded from Pakistan: Paracymus vulgatus Wooldridge, 1977(Wooldridge 1977. In this study P. aeneus is the second representative of the genus from Pakistan.
Subfamily SPHAERIDIINAE Latreille Tribe COELOSTOMATINI Heyden ** Genus Coelostoma Brullé Up to now, 104 species have been described from Afrotropical, Palaearctic and Oriental regions. Until now, no species of this genus was known from Pakistan (Hansen 1999(Hansen , 2004Short and Hebauer 2006).

Family SPERCHEIDAE Erichson
The family Spercheidae is a homogeneous group of beetles composed of only one genus, Spercheus Kugelann. Recent papers mention that this family has 18 species, most of them from the Ethiopian and Oriental zoogeographic regions (Hansen 1991;Hebauer 1997;Darilmaz and Kıyak 2011). Until now, only a single Oriental subspecies, Spercheus belli belli, has been recorded in Pakistan (Hebauer 1997). The species is recorded here also for Pakistan.

Discussion
The present survey of water beetles from Pakistan reveals 19 species and one subspecies of the families Gyrinidae, Dytiscidae, Hydrophilidae and Spercheidae. Two specimens of Copelatus have not yet been identified to the species level. In this study, four genera and 10 species are recorded from Pakistan for the first time: Gyrinidae (one genus and two species), Dytiscidae (three species) and Hydrophilidae (three genera and five species (2) B. nigriceps, H. senegalensis and C. stultum occur in the Afrotropical as well as in the Oriental region. The occurrence of these species in Pakistan supports a hypothesis of a former continuous distribution of some taxa in the 'Old World tropics' from sub-Saharan Africa through the Arabian Peninsula, Southern Iran and Pakistan to India and Southeast Asia.
Animals other than the aquatic Coleoptera have a similar distribution and thus support these hypotheses. These results appear to support the hypothesis advanced by Pearson and Ghorpade (1989) that the tiger beetle fauna on the subcontinent is largely the result of numerous independent contributions from the Afrotropical, the Palaearctic and the Oriental faunas. In addition, our results show similarity to those of Rafi et al. (2010) and Zia et al. (2011).