A preliminary study on the insect fauna of Al-Baha Province, Saudi Arabia, with descriptions of two new species

Abstract A preliminary study was carried out on the insect fauna of Al-Baha Province, south-western part of Saudi Arabia. A total number of 582 species and subspecies (few identified only to the genus level) belonging to 129 families and representing 17 orders were recorded. Two of these species are described as new, namely: Monomorium sarawatensis Sharaf & Aldawood, sp. n. [Formicidae, Hymenoptera] and Anthrax alruqibi El-Hawagry sp. n. [Bombyliidae, Diptera]. Another eight species are recorded for the first time in Saudi Arabia, namely: Xiphoceriana arabica (Uvarov, 1922) [Pamphagidae, Orthoptera], Pyrgomorpha conica (Olivier, 1791) [Pyrgomorphidae, Orthoptera], Catopsilia florella (Fabricius, 1775) [Pieridae, Lepidoptera], Anthrax chionanthrax (Bezzi, 1926) [Bombyliidae, Diptera], Spogostylum near tripunctatum Pallas in Wiedemann, 1818 [Bombyliidae, Diptera], Cononedys dichromatopa (Bezzi, 1925) [Bombyliidae, Diptera], Mydas sp. [Mydidae, Diptera], and Hippobosca equina Linnaeus, 1758 [Hippoboscidae, Diptera]. Al-Baha Province is divided by huge and steep Rocky Mountains into two main sectors, a lowland coastal plain at the west, known as “Tihama”, and a mountainous area with an elevation of 1500 to 2450 m above sea level at the east, known as “Al-Sarat or Al-Sarah” which form a part of Al-Sarawat Mountains range. Insect species richness in the two sectors (Tihama and Al-Sarah) was compared, and the results showed that each of the two sectors of Al-Baha Province has a unique insect community. The study generally concluded that the insect faunal composition in Al-Baha Province has an Afrotropical flavor, with the Afrotropical elements predominant, and a closer affiliation to the Afrotropical region than to the Palearctic region or the Eremic zone. Consequently, we tend to agree with those biogeographers who consider that parts of the Arabian Peninsula, including Al-Baha Province, should be included in the Afrotropical region rather than in the Palaearctic region or the Eremic zone.

introduction Al-Baha Province (Fig. 1) is situated in the south-western part of Saudi Arabia between the Holy Makkah and Asir Regions (Doha 2009), with a population of about 500,000. It is the smallest province in the kingdom of Saudi Arabia (about 10362 km²), situated between longitudes 41°/42° E and latitudes 19°/20° N. This Province is known for its beauty and has many tourist attractions such as forests (about 53 forests), wild life areas, valleys, and mountains. It is characterized by natural tree cover and agricultural plateaus. The region is divided by huge and steep rocky mountains into two main sectors, a lowland coastal plain at the west, known as "Tihama", and a mountainous area with an elevation of 1500 to 2450 m above sea level at the east, known as "Al-Sarat or Al-Sarah" which form a part of Al-Sarawat Mountains range (Alahmed et al. 2010, Ibrahim andAbdoon 2005).
Al-Baha Province consists of six main districts, four of which are located in Al-Sarah sector beside the downtown "Al-Baha", i.e., Al-Aqiq, Al-Mandaq, Al-Qura, and Baljurashi, while two of the districts are located in Tihama sector, namely Al-Mekhwa including Dhee Ain Village (The Marble Village), and Qelwa (website: http://www. albahakfhaa.org/Albaha.htm). The climate in Al Baha Province is greatly influenced by its varying topography. It is generally moderate in summer and cold in winter with average temperatures ranging between 12-23 °C. In Tihama, the climate is hot in summer, warm in spring and mild in winter, with humidity ranging between 52% -67%, and a rainfall less than 100 mm annually. While in the mountainous area, Al-Sarah, The climate is greatly different from that in Tihama although the two sectors are separated by no more than 30 km. The weather is cooler in summer and winter due to its high altitude. Al-Sarah is exposed to the formation of clouds and fog, and this often happens in winter because of air masses coming from the Red Sea, accompanied by thunderstorms. In spring and summer, the climate is mild and pleasant. Also, rainfall is higher with falls in the range of 229-581 mm. The average rainfall throughout the whole province is 100-250 mm annually (websites: http://www.tititudorancea.com/z/weather_al_baha_saudi_arabia.htm).
The purpose of this paper is to present a preliminary list of insect fauna in Al-Baha Province. Such a study is of particular interest as the study area is a part of the Arabian Peninsula which is thought by many authors to touch three of the world's main zoogeographical regions: the Afrotropical, the Palaearctic, and the Oriental (Hölzel 1998).
Many authors agree that the Afrotropical region covers all of Africa south of the Sahara with the island of Madagascar and the nearby smaller islands constituting a distinct subregion. Many authors also include parts of the Arabian peninsula in the Afrotropical region, but there seems to be no agreement as to how much. Sclater (1858) and Wallace (1876) proposed the classical zoogeographical regions and placed the northern border of the Afrotropics along the Tropic of Cancer. Thus, Al-Baha Province was included in the Afrotropical region, and the Northern limit of the Afrotropical region was placed in the Taif area, about 200 km north to Al-Baha (Hölzel 1998). However, according to Uvarov (1938), Greathead (1980), and Larsen (1984) this area should be united with the central Arabian deserts which are either considered part of the Palaearctic, or by some authors as an autonomous Eremic zone (also called the Saharo-Sindian faunal region). All these facts seem to be reflected somehow on the insect faunal composition in Al-Baha Province as shown in the following results.
Undoubtedly, this study is of particular interest also as the insect fauna of Al-Baha Province has not been studied thoroughly before, and this is the first comprehensive study on the entire insect fauna in the region. For this reason, the following previously established data are intended to serve as a basis for further investigations.

Material and methods
Insect material for the present study was collected extensively from different localities in Al-Baha Province, from 2008 to 2012 by the authors using sweeping and aerial nets, bait traps, beating sheets, digging, hand picking, light traps, malaise traps, pitfall traps, sticky traps, tray sifting, and yellow pan traps. Data from specimens preserved in the insect collections and literature records are also taken into consideration.
All taxa are arranged herein in alphabetical order. Localities and date of collection are included for the purpose of mapping distribution and activity periods of species in the study region.

Results
A total number of 582 species and subspecies (few identified only to the genus level) belonging to 129 families and representing 17 orders, have been recorded from Al-Baha Province through the present study as follows:
Al-Baha: September. * Collecting methods of specimens of the order Blattodea: Hand picking and Pitfall traps.
* Collecting methods of specimens of the order Homoptera: Beating sheets and sweeping nets were the main methods; however, specimens of Cicadellidae, Cicadidae and Cixiidae were collected using light traps as well. Al-Baha City: April-July.
Collecting methods of specimens of the order Neuroptera: Light trap was the main method; however, some specimens of Chrysopidae were collected using sweeping nets as well.  (Voss, 1961) Wadi Gaanah: February.

Subfamily: Thiacidinae
Thiacidas adnanensis (Wiltshire, 1980) Adnan: September. Thiacidas cerurodes cerurodes (Hampson, 1916) Al-Baha: September. Head: Frons with whitish pruinose, tending to be silvery at margins, covered with black hairs, and yellowish to brownish scales at the middle, and the scales become longer, more dense and pale above the antennae; ocellar tubercle black; occiput with whitish pruinose, whitish scales at eye margin, short sparse black hairs becoming more dense behind the ocellar tubercle, and long brownish scaly hairs around the occipital cavity; face covered with whitish long scaly hairs and long black hairs; eyes at upper part of frons separated by about twice width of ocellar triangle; antennae black with some pale brownish pruinose. Thorax: Scutum and scutellum covered with fine white and yellowish to brownish white scaly hairs; bristles and hairs black; anterior corners with snowy white scaly hairs, being shaggy and more slender at fore margin; hind margin of scutellum with short white scales; legs black; hairs and bristles black; coxae and tibiae covered with white scales, mixed with brownish white ones on tibiae; claws black; pulvilli grayish; wing hyaline ( Fig. 2) with a feeble basicostal infuscation, with a faint brownish spots on r-m, on the origin of vein R 2+3 , on the middle of cell br slightly af-  ter origin of vein R 1 , and another fainter and smaller one may present also on bm-cu crossvein; squama with a short white fringe; plumula white; coastal hook black with white scales; halteres brown with knobs white at tip. Abdomen: Corners of 1 st tergite with snowy whitish tuft of long scaly hairs; sides of 2 nd and 4 th tergites with tufts of long blackish scales and scaly hairs; sides of 3 rd tergite with tufts of long snowy whitish scales and scaly hairs; bristles of abdomen black and strongly developed; sides of 3 last tergites with long white hairs seen lower to the black bristles; posterior margin of all tergites with snowy whitish scales, becoming more dense and broad at sides especially at sides of 6 th tergite; yellowish white scaly hairs and small scales present across mid-line of 2 nd , 3 rd , and 4 th tergites; tergites with dense black scales lying flat especially on sides of 4 th and 5 th ones. Hypopygium (Fig 3): Posterior processes of gonocoxites long and narrow; epiphallus terminating in a forceps-like process slightly inclined dorsally and continued with a long flange directed ventrally. Patatype female. Similar to holotype male; spermatheca ( Fig. 4)

Family: Tachinidae
Exorista sp. Ghabet Shahba: May-July. * Collecting methods of specimens of the order Diptera: Aerial nets, sweeping nets and malaise traps were the main methods. However, other methods were effective too as bait traps for Calliphoridae and Sarcophagidae; yellow pan traps for Chloropidae, Chironomidae and Syrphidae; sticky traps for Psychodidae; and light traps for Ceratopogonidae and Psychodidae.
This new species is a member of the Monomorium monomorium-group as defined by Bolton (1987), but it does not fit any of the Monomorium species in Bolton's key to the Afrotropical species or the key to the Arabian species given by Collingwood and Agosti (1996). Monomorium sarawatensis superficially seems to be similar to M. affabile Santschi and M. malatu Bolton described from Zaire. The three species share the following characters: dorsum and sides of propodeum and waist blanketed everywhere with dense reticulate-punctate sculpture; fourth (basal) tooth of mandible slightly smaller than the third, and not broadly separated; genae faintly longitudinally striated; body pilosity clubbed. However, sarawatensis can be easily separated by the uniform yellow color, whereas the color of the latter species is dark brown to blackishbrown. In comparison with affabile, sarawatensis is consistently larger (TL 1.77-2.13), versus (TL 1.5) and the eyes are smaller versus EL 0.24 × HW).
The Diagnosis: This new species is characterized by a combination of the following characters: eyes with five-six ommatidia in the longest row; genae faintly longitudinally striated; metanotal groove deep and broad; propodeal dorsum making a weak obtuse angle with propodeal declivity; mesosoma and waist densely reticulate-punctate; body pilosity clubbed. (N=12). Holotype worker. Head distinctly longer than broad, with a nearly straight posterior margin and shallowly convex sides; head dorsum smooth and shining with few scattered hair-pits; anterior clypeal margin feebly concave between a pair of obtusely projecting angles which separate anterior and lateral margins; clypeal carinae broadly separated and subparallel; eyes with five-six ommatidia in the longest row (EL 0.17-0.22x HW). With head in profile the posterior margins of eyes at the midlength of sides; antennal scapes, when laid back from their insertions, failing to reach posterior margin of head; genae faintly longitudinally striate. Mesosoma in lateral view with the promesonotum straight or feebly convex; metanotal groove deep and broad; propodeal dorsum making a weak obtuse angle with propodeal declivity; mesosomal pilosity few and sparse, two pairs of erect setae on pronotum, five or more on mesonotum, three on propodeum; propodeal spiracle small and pinhole-like; mesosoma densely reticulate-punctate except for pronotal sides which are nearly smooth and shining. Petiolar node high and acuminatein profile, usually with two pairs of erect setae, petiolar peduncle thick and short. Postpetiole in dorsal view clearly broader than long. Petiole and postpetiole densely reticulate-punctate. Color uniformly yellow. Body pilosity clubbed.  Note. Specimens were photographed by Erin Prado using a JVC KY-F70B 3CCD digital camera attached to a Leica M420 stereomicroscope. All digital images were processed using Auto-Montage (Syncroscopy, Division of Synoptics Ltd, USA) software. Images of the specimens are available in full color on www.antweb.org.

Subfamily: Vespinae
Vespa orientalis Linnaeus, 1771 Wadi Turabet Zahran: May-August. * Collecting methods of specimens of the order Hymenoptera: Aerial nets, sweeping nets and malaise traps were the main methods; however, the yellow pan traps were effective for small Hymenoptera as well, and ants (Formicidae) were collected using tray sifting.
Insect species richness in Al-Baha Province has been compared between sectors, and with the total species richness in the province as a whole. Results demonstrated that the two sectors (Tihama and Al-Sarah) are varied in their species composition (Fig. 16). The figure summarizes variation in species composition in two ways: firstly, by the number of species shared between the two sectors, and secondly, by the number of species unique to each sector. It was found that 465 species have been recorded from Al-Sarah, with 408 of them (88%) unique; while 174 species have been recorded from Tihama, with 117 of them (67%) unique. However, only 57 species have been recorded as common to both sectors, representing only about 10% of all species recorded from the province as a whole. These results clearly suggest that each of the two sectors of Al-Baha Province (Tihama and Al-Sarah) has its own insect community.
Most of insect species here recorded from Al-Baha Province are characteristic of the Afrotropical region. Tabel (1) indicates the broad scale distribution patterns suggesting a closer affiliation to the Afrotropical region than to the Palearctic region or the Eremic zone. This affiliation was obviously greater in Tihama (69%) than in Al-Sarah (60%). The study showed Palaearcic elements comprising 27% or less in both sectors, in addition to some few Oriental elements (3% or less).

Discussion
The south-western part of Saudi Arabia, including Al-Baha Province, is considered by many authors to be the most important part of the country and the Arabian Peninsula in general in terms of vegetation and speciation. This area is similar to the high altitude mountains of north-eastern and eastern parts of Africa, both floristically and ecologically (Zohary 1973 andEig 1938).  Figure 16. Insect species in the two main sectors (Tihama and Al-Sarah) of Al-Baha Province. The total number of species in each sector is given in bold, the number of species occurring in common in the two sectors is given along the line joining them, and the number of species unique to each sector is given within parentheses within circles.
Insect diversity (richness) shows a positive correlation with plant diversity (El-Moursy et al. 2001), in other words, the species diversity of consumers should depend to some degree upon the diversity, as well as the productivity, of their food resources (Davidson 1977). Hence, the variation in insect richness in the two sectors of Al-Baha Province seems to reflect their varying vegetation patterns. This variation in insect richness could also be a result of the distance (more than 25km) and altitude (more than 1500 m) between the two sectors, where distance and height could affect the ability of species to disperse between sectors (Fisher 1996). Consequently, each of the two sectors has its own insect community. There is also little doubt that abiotic conditions (relative humidity, soil moisture, temperature, etc.) may affect this pattern of insect distribution in Al-Baha Province.
Considering the insect fauna in Al-Baha Province as a whole, we can obviously conclude that Al-Baha has an extraordinary complex and interesting insect fauna. This may be attributed to its geographical position at the junction of two of the world's main zoogeographical regions: the Afrotropical and the Palaearctic (Hölzel 1998).
The vegetation of Arabian Peninsula is more or less similar to that of the northeastern and northern parts of the African Continent. So, some present day biogeographers are of the opinion that the biogeographical divisions within the northeastern and eastern parts of Africa should be extended towards east to cover the regions within the Arabian Peninsula too, namely "Afromontane Archipelago", covering the high altitude regions of the southern Al-Sarawat Mountains (Zohary 1973;Eig 1938).
Indeed, the present preliminary study is not sufficient to draw more than general conclusions about insect zoogeography in Al-Baha Province. However, the insect faunal composition in this region has an Afrotropical flavor as the Afrotropical elements have been predominantly indicated. Consequently, we tend to agree with those boigeographers who believe that parts of the Arabian Peninsula, including Al-Baha Province, should be included in the Afrotropical region rather than in the Palaearctic region or the Eremic zone, but we cannot indicate the northern border of this region exactly. Especially, Zoogeographical regions often have definable boundaries due to physical barriers, such as mountains, deserts, or water. However, where no such barriers exist, each region gradually merges with the next, pockets of one extending some way into the other due to variable environmental conditions. Such transitional zones may themselves have certain definable characteristics and are often classified as distinct regions. The desert between the Palaearctic and Afrotropical regions is one such zone, and is known as the Afroeremic zone (de Lattin 1967), the Eremic zone (Uvarov 1938;Greathead 1980;Larsen 1984) or the Saharo-Arabian subregion (Takhtajan 1986). However, the northern border of the Afrotropical Region was proposed to be along the Tropic of Cancer (Sclater 1858;Wallace 1876).
We think that the exact indication of the northern border of the Afrotropical region requires more study, not only of the insect fauna but also of the flora and other animal faunas in central deserts, south, south-eastern, and south-western parts of Saudi Arabia.