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Observations on the habitat, colouration and behaviour of the tiger beetle Callytron monalisa (W. Horn, 1927) (Coleoptera: Cicindelidae) on the Arabian Gulf coast of the United Arab Emirates.

Introduction

The tiger beetle Callytron monalisa (W. Horn, 1927) was first recorded from the UAE in early September 2007, when specimens were collected by Brigitte Howarth and Drew Gardner at a mercury vapour light trap on Reem Island in Abu Dhabi emirate. The next summer, in late July 2008, the senior author photographed several individuals in an arm of Khor Zawra, a coastal lagoon in Ajman emirate. C. monalisa thus became the 13th tiger beetle species recognised from the UAE (Cassola et al. 2012; Wiesner 1993, 1996).

Both of those initial sites are along the Arabian Gulf coast of the UAE. The light trap was set up on muddy ground beside a mangrove creek. The Ajman record was from an area of very fine, waterlogged mud bordering an embayment of the upper reaches of the main channel, where no mangroves were present in the immediate vicinity. The soft mud habitat is quite limited at Khor Zawra and was associated with two other species whose range at Khor Zawra is correspondingly limited: (i) a modest population of an air-breathing gastropod of the Salinator fragilis complex (now considered likely to represent a new genus and probably a new species) (R. Golding, pers. comm.); and (ii) at least one Echiuran (spoonworm), probably Ikeda sp. (Hornby 2005). These initial observations raised the possibility that C. monalisa might have very narrow habitat requirements.

Subsequently, in the course of other research, C. monalisa was found to be present and locally common at two other Arabian Gulf sites in the northern Emirates, on a variety of muddy substrates, providing some additional information about this little known species.

Colouration

On 25 August 2013, on the margin of the lagoon at Khor al-Beidhah, Umm al-Qaiwain, dozens of C. monalisa were active in mid-morning (0830-0930 hrs) on lumpy, crab-burrowed ground exposed in the uppermost littoral zone between cyanobacterial mats and halophyte vegetation, primarily Arthrocnemum macrostachyum (Fig. 1). Three or four pairs were observed in prolonged copulation, making them somewhat easier than usual to photograph (Fig. 2).

All of the C. monalisa seen at Khor al-Beidhah (including the sexually active individuals) showed colouration consistent with the two earlier UAE records: the head and thorax were mostly a metallic copper colour, rimmed with green, and the elytral markings were more or less black (Fig. 2; see also Cassola et al. (2012), Fig. 1). This is in contrast to the "beautiful deep blue-green colour" for which C. monalisa is otherwise known, and it had already been speculated that, if this colour difference proved to be a consistent characteristic of the UAE population, it could represent an undescribed subspecies (Cassola et al. 2012).

Two weeks later, on 7 September 2013, observations of C. monalisa at Khor Hulaylah, Ra's alKhaimah, gave a broader perspective. There, C. monalisa was observed in mid-afternoon (ca. 1530 hrs) on glutinous mud, in somewhat smaller numbers than at Khor al-Beidhah. All individuals seen at Khor Hulaylah (including a number of mating pairs) showed the deep blue-green head and thorax typical of the species, and some showed blue-green elytral markings as well (Fig. 3).

Although not conclusive, the Khor Hulaylah observations cast doubt on whether the observed colour differences could best be explained by means of a distinct UAE subspecies; among other things, the geographic boundary between the two subspecies would have to lie within the ca. 55 kilometres of relatively uniform coastline between Khor al-Beidhah and Khor Hulaylah. Instead, it seemed at least equally plausible that the differences might be attributable to other factors such as development of the eventual blue-green colour over time, with increasing maturity in a seasonal coastal population. That hypothesis could be tested by a monitoring programme of more closely-spaced field visits, ideally to multiple adjacent khors (lagoons), during the period from late July to mid-September when C. monalisa has been found to be present locally.

It was not feasible for the authors to organise such a programme in 2014, but a single investigatory visit was made to Khor Al-Beidhah in mid-morning on 15 September 2014 to see whether C. monalisa could be found there again, and, if so, whether there was any change from the mostly copper colouration observed in late August 2013.

C. monalisa was successfully found again at Khor al-Beidhah, at the original location but on a somewhat broader range of substrates than before, including flat, firm, upper intertidal mud with an incipient film of cyanobacteria (Fig. 4). Again, dozens of individuals were observed. But this time, three weeks later in the year, the majority of the individuals seen were intermediate in colouration between the two 2013 extremes: The head was mostly green (but not bluegreen), with yellowish highlights laterally, and the thorax was mostly green with only a small patch of copper colour dorsally (Fig. 5), although both head and thorax reflected copper highlights when viewed at a broad angle to the sunlight. Three individuals appeared to have an almost fully dark green head and thorax, while a larger number were mostly copper coloured and a few were almost entirely so. We observed at least eight mating pairs, most of which were intermediate in colouration (Fig. 6).

We interpret these results as supporting the hypothesis of progressive colour change over time, from August through September. At a minimum, our observations argue for caution in postulating a simple subspecific dichotomy to account for colour differences. However, our observations to date do not establish a continuum that would negate the subspecies hypothesis. In particular, (i) in 2014, the Khor al-Beidhah population remained mostly 'intermediate' in mid-September, beyond the early September date by which the Khor Hulaylah population was already fully blue-green in 2013; (ii) mating took place at Khor al-Beidhah among individuals that had not yet achieved "typical" bluegreen colouration; and (iii) no individuals seen at Khor al-Beidhah approached the very deep blue-green colour of those at Khor Hulaylah. Our observations did not identify any differences in the time of appearance (emergence or arrival) of C. monalisa at these two sites, in either 2013 or 2014.

Mating and mate guarding

As in many tiger beetle species, mating in C. monalisa was a prolonged affair, lasting 5-10 minutes or more and including an extended period of mate guarding by the male, beyond actual copulation. Males were slightly smaller than females, whom they clasped with their formidable-looking, specialised mandibles (Figs. 2, 3 and 6). Pairs often remained stationary for a minute or two if undisturbed, but the female nevertheless moved intermittently, with the male still draped astride her abdomen, in copulatory embrace (amplexus) but no longer in copula. The mating female, while stationary, was frequently observed to press the tip of her abdomen lightly into the mud surface, then flick it backwards a few times, making a slight depression (Fig. 6). This behaviour almost certainly represented oviposition, with the male still on board an example of very thorough mate guarding.

Other sympatric tiger beetle species

If the observations reported here are representative, and in particular if C. monalisa is most active on upper sabkha in daylight hours at the height of the Arabian summer, this may help to explain why it was not recorded sooner.

Three other diurnal tiger beetle species were recorded at Khor al-Beidhah, Khor Hulaylah and neighbouring UAE lagoon sites during the time period of the above observations of C. monalisa, and are illustrated here. None, however, were present in association with C. monalisa:

Hypaetha schmidti W. Horn, 1927 (Fig. 7): The largest of the UAE's diurnal tiger beetles, a single individual was observed at Khor al-Beidhah, where it scoured an emergent sand bank featuring burrows and pellets of a pellet-rolling crab (probably Scopimera crabricauda), occasionally entering the crab burrows. It has been reported to feed on smaller crabs in Saudi Arabia (M.PT. Gillett pers. comm.). At Khor Kalba, on the East Coat of the UAE, H. schmidti has been observed to forage along the line of the retreating tide, and also to enter small crab burrows.

Salpingophora hanseatica (W. Horn, 1927) (Fig. 8): Two individuals of this rare and relatively large species were recorded at Khor Zawra in Ajman, ca. 20 kilometres from Khor al-Beidhah, at midmorning in mid-August 2013, on flat, firm, sandy mud in the uppermost intertidal zone, along with Calomera aulica (see below).

Calomera aulica (Dejean, 1831) (formerly Lophyridia aulica) (Fig. 9): This is the most common of the UAE's coastal tiger beetles, recorded on sandy or shelly mud at all of the Northern Emirates khors and on all of the occasions mentioned above. At Khor al-Beidhah, the populations of Calomera aulica and Callytron monalisa did not overlap. C. aulica frequented firmer, sandier substrate, typically with considerable gravel-size shell debris. Also C. aulica, unlike C. monalisa, remained active through the midday hours, although many individuals (including mating pairs) retired intermittently to the shade of saltbush vegetation.

References

Cassola, F., Gardner, D., Feulner, G.R. and Howarth, B. 2012. Callytron monalisa (W. Horn, 1927) from the Arabian Peninsula (Coleoptera: Cicindelidae). Zoology in the Middle East 55(1):137-138.

Hornby, R.J. 2005. An Intertidal Spoon Worm (Phylum Echiura) in the United Arab Emirates: Occurrence, Distribution, Taxonomy and Ecology. Tribulus 15.1: 3-8.

Wiesner, J. 1993. Uber die Cicindelidae (Coleoptera) der Vereinigten Arabischen Emirate. Entomologische Zeitung mit Insektenborse, 103: 249-260.

Wiesner, J. 1996. Weitere Mitteilungen uber die Cicindelidae (Coleoptera) der Vereinigten Arabischen Emirate. Entomologische Zeitung mit Insektenborse, 106: 382-384.

Gary R. Feulner

Chadbourne & Parke

P.O. Box 23927

Dubai, United Arab Emirates

e-mail: grfeulner@gmail.com

Binish Roobas

Dubai, United Arab Emirates

e-mail: johanruphus@hotmail.com
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Author:Feulner, Gary R.; Roobas, Binish
Publication:Tribulus
Article Type:Report
Date:Jan 1, 2014
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