Cicindelinae of Sri Lanka: New record of the arboreal tiger beetle Tricondyla gounellei Horn, 1900

This article is published under the Creative Commons CC-BY-ND License (http://creativecommons.org/licenses/by-nd/4.0/). This license permits use, distribution and reproduction, commercial and non-commercial, provided that the original work is properly cited and is not changed in anyway. Abstract: Information is provided on the newly recorded Tricondyla gounellei Horn, 1900, an arboreal tiger beetle, hitherto known only from Southern India, with this being its fi rst from Sri Lanka. Following fi eld surveys conducted from 2017 to 2019 in forty-one locations in the country, this species was recorded from two locations namely, Vellankulam in Mannar District and Kirinda in Hambantota District. Tricondyla gounellei, closely resembles Tricondyla granulifera Motschulsky, 1857 previously recorded from Sri Lanka. However, T. gounellei can be distinguished from T. granulifera by the smaller body size, short elytra that are narrower in the middle and palpi with black terminal joints which in T. granulifera is red.


INTRODUCTION
Tiger beetles (Coleoptera, Cicindelinae) are an important group of predatory insects that play a major role in ecosystems, being an integral part of the food chains and bioindicators of the environment. Thirty-one species of arboreal tiger beetles are known from Sri Lanka of which twenty-fi ve species are endemic to the island (Dangalle, 2018). According to the existing records (Tennent, 1860;Horn, 1904;Fowler, 1912;Naviaux, 2002) and collections maintained in the country (National Museum of Colombo, Sri Lanka; Horticultural Crop Research and Development Institute, Gannoruwa, Sri Lanka) the arboreal tiger beetles in Sri Lanka belong to fi ve genera -Collyris (1 species), Protocollyris (1 species), Neocollyris (12 species), Derocrania (12 species) and Tricondyla (5 species). About 45 species of arboreal tiger beetles of the genus Tricondyla occur worldwide (Bousquet, 2012). Recent surveys dating from 2017 (Abeywardhana et al., 2018;2019) were conducted island-wide to recheck the original locations of the previously recorded species and to record the current distribution of the group especially in light of the high endemicity of this group, particularly at a time when their arboreal habitats are subjected to destruction.
An arboreal tiger beetle species previously not recorded from the country (according to past literature and specimen collections) collected during the recent surveys is reported here. This article gives a description of the external morphology, locations and habitat type of the newly recorded Tricondyla gounellei in Sri Lanka, and how it diff ers from its closest species T. granulifera.

METHODOLOGY
In a survey conducted from 2017 to 2019, 41 locations in 18 districts covering the nine provinces and three climatic zones of the country were investigated for arboreal tiger beetles (Abeywardhana et al., 2019). A variety of habitat types such as beaches, coastal areas, marshlands, forests, woods, home gardens and agroecosystems were surveyed for arboreal tiger beetles using visual encounter surveys (VES). Tiger beetles encountered were collected using insect nets and by

RESULTS AND DISCUSSION
Of the 41 locations surveyed previously, 13 locations yielded arboreal tiger beetles. Upon identifi cation the collected tiger beetles belonged to seven species in three genera; genus Derocrania (4 species), genus Neocollyris (1 species) and genus Tricondyla (2 species) identifi ed as T. granulifera and T. gounellei. According to the existing information, six of these species have been previously recorded from several locations in the country (Dangalle, 2018), except Tricondyla gounellei, hence, a new record for Sri Lanka.

Original description of Tricondyla gounellei
A description of T. gounellei from India is provided by Fowler (1912) in his works of the Cicindelidae of British India. T. gounellei specimens collected from trees of Anaimalai Hills, Ramnad in Madras, India have been described with no distinction of the two sexes. According to Fowler's descriptions T. gounellei is 23 mm in length with an elongate and parallel-sided pronotum. The elytral surface is covered with transverse punctiform impressions, of which the anterior few are confl uent and form irregular wavy lines, middle are more separate and the impressions at the apex are very fi ne and scanty. The palpi are black while the labrum and fi rst four joints of the antennae are metallic black. The third and fourth joints of the antennae are ringed in red.

Description of Tricondyla gounellei collected during the study
Male and female specimens of T. gounellei collected are morphologically somewhat similar but the males can be distinguished by the genitalia and the 3 rd tarsomere of the fore-leg that has a medial lobe [ Figure 1(a)], which is absent in the female [ Figure 1(b)]. Males (n = 3) are slightly larger; with a mean body length of 21.16 ± 0.29 mm than the females (n = 2) 20.42 ± 0.14 mm. Adults have metallic black eyes, palpi, labrum, antennae, collar, pronotum, fused elytra and legs (Figures 2 and  3). Pronotum is smooth, cylindrical and elongated with parallel-sides. Elytra fused, cylindrical and humped in apical half (Figure 3).
Specimens of T. gounellei (male = 3, female = 2) are deposited in the insect collection held in the Department of Zoology and Environment Sciences of the University of Colombo and bear the voucher specimen numbers LA_ DOZE.13, LA_DOZE.14, LA_DOZE.15, LA_DOZE.23, LA_DOZE.24 (5 specimens). All specimens were collected by the fi rst author, Lakmini Abeywardhana.

Tricondyla gounellei and Tricondyla granulifera
The newly recorded Tricondyla gounellei is very similar to T. granulifera in having an elongate, parallelsided neck and pronotum, uniformly shiny black body, transverse sculpture on elytra, very prominent large eyes, long and fi liform antennae and a large labrum with six labral teeth. However, T. gounellei have shorter elytra than T. granulifera, that are less narrow in the middle and thus are smaller. Elytra of T. granulifera are long and are broader in the middle. The elytral sculpture of T. granulifera is highly rugose as in rugose corals (Cnidaria, Rugosa), which in T. gounellei is much less. Further, T. granulifera is slightly larger (Male: 24.08 ± 0.62 mm, n = 2; Female: 23.22 ± 0.76 mm, n = 2) than T. gounellei (Male: 21.16 ± 0.29 mm, n = 3; Female 20.42 ± 0.14 mm, n = 2). Identifi cation and separation of species by the authors are based on the keys and descriptions of Horn 1904, Maindron 1904, Fowler 1912and Naviaux 2002 The genus Tricondyla is represented in Sri Lanka by fi ve species, namely, Tricondyla femorata, Tricondyla tumidula, Tricondyla coriacea, Tricondyla nigripalpis and Tricondyla granulifera of which the latter three species are endemic (Dangalle, 2018). The present study adds a previously unrecorded species, Tricondyla Journal of the National Science Foundation of Sri Lanka 48(2) June 2020 gounellei to the list. T. gounellei has been recorded from India from two locations: from Anaimalai Hills in Ramnad, Madras (Fowler, 1912) and from the Tamil Nadu State (Kirk-Spriggs & Wiesner, 1992). Similar climatic conditions prevail between Southern India and Northern Sri Lanka (Dittus, 2017), resulting in climatically-induced habitat diversifi cation (Bossuyt et al., 2004). Therefore, it is likely that the arboreal tiger beetle T. gounellei had dispersed from Southern India to Sri Lanka and established itself in this country due to the similar dry habitats prevailing in the two regions.
The manner in which T. gounellei reached Sri Lanka is not known. The Skimmer (Pantala fl avescens), a small dragonfl y with a weak fl ight ability is believed to have travelled from India to Sri Lanka by fl ying on winds at altitudes above 1000 m (Rodrigo, 2011). Therefore, it is highly likely that T. gounellei, fl ightless and small bodied got carried over long distances by means of air currents.
With the discovery of T. gounellei the genus Tricondyla is represented in Sri Lanka by six species, of which three species are endemic to the island and the other three species occur both in Sri Lanka and India.  According to Fowler (1912) Tricondyla gounellei in India were found running on the bole of trees in the month of May. In the present study too, this arboreal tiger beetle species was found foraging on the trunks and branches of trees; Mangifera indica, Anacardium occidentale and Ziziphus mauritiana. Furthermore, the tiger beetle, T. gounellei in Sri Lanka was collected in the months of March and August.

CONCLUSIONS
The arboreal tiger beetle collected from Vellankulam and Kirinda in the Arid Zone of the island is identifi ed as Tricondyla gounellei, a new record for Sri Lanka. T. gounellei was previously known only from Madras and Tamil Nadu State in Southern India. The newly recorded T. gounellei closely resembles T. granulifera, previously recorded from Sri Lanka, but diff ers from it in several key features. Currently, the number of species in the genus Tricondyla stands at six in Sri Lanka.