J. South Asian nat Hist, ISSN 1022-0828. March, 1997. Vol.2, No. 2, pp. 199-204,3 figs. © Wildlife Heritage Trust of Sri Lanka, 95 Cotta Road, Colombo 8, Sri Lanka.

Observations on Indothele lanka Coyle, an ischnotheline funnelweb from Sri Lanka (Araneae, , )

Matjaz Kuntner1, Frederick A. Coyle2 and D.P. Wijesinghe3

Abstract The first natural history observations on the endemic South Asian funnelweb spider Indothele indicate that Indothele lanka Coyle maybe a fairly typical ischnotheline spider in terms of web design, web substrate requirements, and prey capture behaviour, but atypical in its preference for wet forest and its occurrence inside primary ram forest. Character state analysis of the new sam­ ple of females supports earlier hypotheses (Coyle, 1*995) about the systematics of I, lanka, including its status as sister species of the other three Indothele spe­ cies, all endemic to India. Because of restricted distributions and probable de­ pendence on threatened habitats, I. lanka ahd its congeners deserve increased attention. j

Key words: Mygalomorph spider, Indothele, Sri Lanka, Sinharaja World Heritage Site.

Introduction Unlike the other four genera in the widespread tropical funnelweb mygalomorph spider subfamily Ischnothelinae, almost nothing is known about the natural history of the recently described genus, Indothele, which consists of one species in Sri Lanka and its sister clade of three species in southern India (Coyle, 1995). With that in mind, the first author searched for the Sri Lankan species, Indothele lanka Coyle, during a recent visit (13 January - 10 February 1995) to Sri Lanka. Herein we describe observations he gathered at two sites near Kudawa in Ratnapura District of Sabaragamuwa Province in southwest­ ern Sri Lanka; one site (site A) is at an elevation of 500 m near M. Wijesinghe's

1 Pod Jelsami 32,1000 Ljubljana, Slovenia. 2 Department of Biology, Western Carolina University, Cullowhee, NC 28723, U.S.A. 3 Department of Entomology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, U.S.A. K u n tn er , C o yle & W ijesin ghe

guesthouse just outside the Sinharaja World Heritage Site (hereafter Sinharaja WHS) and the other (side B) is at an elevation of 500-750 m inside the Sinharaja WHS along the Waturawa and Moulawella nature trails about 2-3 km from the first site. We also-update the description of I. lanka (which had previously been known from two males and seven females) with an analysis of six addi­ tional females. We urge others to follow our lead and learn more about this species and the three even more poorly known Indian members of the genus, which, like I, lanka, appear to be restricted in distribution (Coyle, 1995) and threatened by habitat destruction. The specimens collected in this study are deposited in the National Museum at Colombo, Sri Lanka, and the Slovene Museum of Natural History at Ljublijana, Slovenia. Natural history Ecology. Although I. lanka was sought in all 21 localities visited in Sri Lanka, it was found only at the two above-mentioned sites, which are very close to the other two recently recorded localities for this species (in the Morapitiya Forest Reserve and Sinharaja World Heritage Site) (Coyle, 1995). This cluster of four I. lanka sites is centered in Sri Lanka's wet zone, which occupies the southwestern quarter of the country and receives 3000 to over 5000 mm of

- 10°

Figure 1. Solid black circles on map of Sri Lanka mark known localities of Indothele lanka Coyle; the three clustered solid black circles mark four sites in and near the Sinharaja WHS where this species was found between 1983 and 1995, and the fourth solid black circle desig­ nates a locality (Na- walapitiya) 70 km north of these sites where Sherriffs (1919) observed this spe­ cies in about 1915. Unfilled circles mark the 19 other localities where first author in 1995 searched for this species but was unable to find it. Dotted line repre­ sents approximate bound­ ary between the wet and dry zones of Sri Lanka 80 ° ° 81 (Erdelen, 1988).

200 J. South Asian nat. Hist Observations on In d o t h e l e la n k a rainfall in a typical year (Erdelen, 1988) (Fig. 1). The were found only in primary and secondary rain forest and were particularly common at site B, where several hundred webs were observed. Both sites A and B average over 5000 mm of rain per year (M. Wijesinghe, pers. comm.). Although the webs of I. lanka were found inside both secondary and primary rain forest on the ground (among rocks, tree roots, and leaf litter) and on tree trunks, they ap­ peared to be most common on the banks of roads and trails in these forests, where they seemed to replace the lycosid (.Hippasa) and psechrid [Psechrus torous (O.P.-Cambridge)] sheet/funnelweb spiders that are often common on road banks elsewhere in Sri Lanka. Ten of the visited localities which do not harbor I. lanka populations He in the dry zone of Sri Lanka in disturbed habi­ tats in areas that had once been covered with dry and mesic semi-evergreen forest and intermediate forest (Erdelen, 1988). The other nine localities lack­ ing I. lanka are in the wet zone, but the lowland and submontane rain forests native to this zone no longer remain at any of these localities. The only other record for I. lanka known to us is Sherriffs1 (1919) observation of ischnotheline spiders, undoubtedly. I, lanka, together with P. torvus "on the road-banks of the upcountry tea estates" near Nawalapitya about 70 km north of the Sinharaja Reserve at about 920 m elevation in an area he reported to average over 6300 mm of rain per year. In total, these observations indicate that I. lanka is prob­ ably restricted to rain forest and adjacent disturbed habitats in the wet zone of southwestern Sri Lanka. Rain forest (particularly primary rain forest) is unusual habitat for ischnothelines; all other species whose habitats are known appear to prefer more open and dryer habitats (Coyle, 1995). It may be that the South Indian species of Indothele live in dryer habitats than does I. lanka [Acacza-dominated arid scrub habitat is common near the type locality of Indothele mala Coyle (Coyle, 1995)]. However, it should be emphasized that reliable habitat data for the South Indian Indothele species are lacking and that there are remnant patches of humid to wet forest at or very near the sites where I. mala and Indothele rothi Coyle have been collected (N. Meegama & P. Rasmussen, pers. comm.). The apparent inability of I. lanka to survive in habitats other than rainfor­ est probably makes it more extinction-prone than most other ischnotheline species. The majority of Sri Lankan angiosperm and vertebrate endemics, like I. lanka, are restricted to the wet zone, and most of these are further restricted to the remaining patches of natural forest which have so far managed to sur­ vive the spread of timber harvesting, tree farming, and agriculture (Erdelen, 1988). Hopefully, the nearly 90 km2 Sinharaja WHS, which is the only large area of more or less undisturbed rain forest in Sri Lanka, the chief refuge of Sri Lankan endemics, and an International Biosphere Reserve (Erdelen, 1988; Green, 1990), will be protected from the kinds of changes that have probably already reduced and obliterated I. lanka populations in other parts of the wet zone.

Behaviour. As is common in other ischnotheline species, I. lanka webs are typically clustered; for example, on one roadbank eight adult and nine juve­ nile webs occured a 7 X 1.5 m area which was 7 m from the next web. The

Vol. 2., No. 2. 201 K u n t n e r , C o y l e & W ije s in g h e

Figure 2. Photos of two Indothele lanka webs on roadbank in Morapitiya Forest Reserve. webs are similar to those of other ischnothelines (Coyle, 1995). The tubular silk retreat, typically extending 5-10 cm into natural cavities and crevices, opens out onto a capture web consisting of one to several sheets inclined at different angles and extending outward in different directions to attachment points on nearby ground, rock, root, leaf or other surfaces (Fig. 2). Each sheet

202 J. South Asian nat. Hist. Observations on In d o t h e l e lan ka

consists of areas o f very fine close-spaced threads (which may give the web a faint blue cast) which are supported by "cables" of cohering treads. Some threads may extend up from the capture sheets to substrates as far as 40 cm above the sheet. The approximate area covered by the dominant plane of the capture web of seven adults and near-adults ranged from 80 to 600 cm2 and averaged 244 cm2. Smaller webs are simpler (less three-dimensional) than larger webs and may consist of little more than a single fan-shaped sheet. A dult I. lanka capture webs, like those of Lathrothele and Andethele species, are generally smaller and less three-dimensional than those of the larger-bod- ied species of and Thelechoris (Coyle, 1995). Indothele lanka w ebs often contain dead leaves, soil particles, and other debris. Despite careful searching, no symbionts were observed living in the webs. Spiders were commonly positioned facing out from the mouth of the retreat during both day and night. They were very shy and quickly retreated deep into the retreat if the observer approached carelessly or touched the web. Ants dropped in the web were approached with a series of short rapid dashes separated by relatively long pauses, the typical ischnotheline approach pat­ tern (Coyle & Ketner, 1990; Coyle, 1995). Ant remains were common in re­ treats. One female had an egg sac (15 X 20 mm) in her retreat, and spiderlings were seen in the retreats of some other females.

Morphology. Figure 3 shows the unusually long and flexible pair of posterior lateral characteristic of ischnotheline spiders and the dark back­ ground colour and pale paired dorsal abdominal marks charcteristic of I. lanka. Individuals appear significantly darker when alive than after preservation in ethanol. Analysis of all character states of the six adult females collected by

Figure 3. Photograph of live adult female Indothele lanka from Sinharaja World Heritage Site: spider had been removed from its web and placed on the ground.

Vol. 2., No. 2. 203 K u n tn er, C o yle & W ijesin gh e the first author (two at site A and four at site B) clearly support the hypoth­ esis that they are conspecific with the seven females described by Coyle (1995). Quantitative character values for the current total sample of 11 measured I. lanka females (including the six newly measured ones) are as follows (Meth­ ods and character abbreviations given in Coyle [1995]. Measurements in mm. Range, mean, and standard deviation given.): CTP = 7-11 (8.5±1.2), CDP = 0- 1 (0.4±0.5), CTR = 8-12 (10.5+1.0), CDR = 6-12 (9.8±1.9), PTkrS = 6-9 (8.0±1.0), ITarS = 0-2 (0.5±0.7), MC = 50-127 (94±25), CL = 3.47-5.24 (4.49+0.70), CW = 3.04-4.62 (3.94±0.59), CS - 0.52-0.85 (0.73±0.09), AMD = 0.20-0.28 (0.24±0.03), AMS = 0.09-0.19 (014±0.03), OQW = 1.00-1.48 (1.27±0.18), OL = 0.00-0.06 (0.03±0.02), SL = 1.92-2.78 (2.44±0,34), SW = 1.74-2.48 (2.16±0.30), IFL = 2.54- 3.81 (3.27±0.50), ITL = 1.73-2.62 (2.25±0.34), IML - 1.81-2.62 (2.27±0.32), ITarL = 1.08-1.50 (1.30±0.16), LSL1 = 1.46-2.31 (1.89±0.30), LSL2 = 1.31-2.08 (1.70±0.28), LSL3 = 3.16-5.31 (4.32±0.76), CDR(100)/CL = 181-289 (224±53), CS(100)/CW = 16.2-23.1 (18.6+2.2), AMD(100)/CL = 4.4-6.1 (5.3+0.5), OQW(100)/CL = 27.3-29.9 (28.4±0.7), SW(100)/SL = 84-92 (88.6±2.3), ITL(100)/ CL = 48-53 (50.2±1.3), LSL3(100)/CL = 89-102 (95±5). Coyle (1995) cited several character states that were diagnostically useful in separting I. lanka from the other Indothele species. The only one of these that is now diagnostically less useful is OQW(IOO) / CL. The new (often slightly increased) ranges of character state variation for I lanka females require no modification in the character state assignments used in Coyle's (1995) cladistic analysis and, therefore, do not contradict the hypothesis that I. lanka is the sister species of the three Indian species of Indothele. Acknowledgements We thank M. Wijesinghe for his generous hospitality. Literature cited Coyle, F.A. 1995. A revision of the funnelweb mygalomorph spider subfamily Ischnothelinae (Araneae, Dipluridae). Bull. American Mus. Nat. Hist., (226): 1-133. Coyle F.A. & N.D. Ketner. 1990. Observations on the prey and prey capture-behaviour of the funnelweb mygalomorph spider genus Ischnothele (Araneae, Dipluridae). Bull. British Arachnol. Soc., 8 (4): 97-104. Erdelen, W. 1988. Forest ecosystems and nature conservation in Sri Lanka. Biol. Conservation, 43:115-135. Green, M.J.B. 1990. IUCN directory of South Asian protected areas. IUCN, Gland, Switzerland and Cambridge. 294 pp. Sherriffs, W.R. 1919. A contribution to the study of South Indian arachnology. Ann. Mag. Nat. Hist., (ser. 9) 4(22): 220-253.

204 J. South Asian nat. Hist. J. South Asian nat. Hist., ISSN 1022-0828. March, 1997. Vol.2, No. 2, pp. 205-216,4 figs., 1 tab. © Wildlife Heritage Trust of Sri Lanka, 95 Cotta Road, Colombo 8, Sri Lanka.

Seasonal variation of the food and feeding habits of the Eurasian otter Lutra lutra (Carnivora: Mustelidae) in Sri Lanka

Padma Ktunari de Silva*

Abstract The diet of three otter groups living in different stream/river habitats was monitored weekly over a period of two years by spraint analysis. The percentage frequencies of the’ major food items of crab, fish and frog in the three groups were 85%, 30% and 8%; 80%, 25% and 9%; 72%, 31% and 8%, respectively. The dry weight analysis of the food items gave a similar order of importance. The frequencies of crabs in spraints varied significantly among the three habitats, while the frequencies of fish did not differ significantly between two of the habitats. The abundance of fish in the diet, in general, varied more significantly than that of crabs over the study period. The degree of seasonal variation of food, as determined quarterly, differed in different habitats. Usually, there were less fish in the diet during the heavy rainy months. The difficulty in catching fish during these periods was probably due to the rapid flow and high turbidity of water. The otters foraged only during the small hours of the night and their foraging range appeared to be about 5 km along the streams and rivers.

Key words: otter, Lutra, Carnivora, feeding, predation, tropical, stream, Sri Lanka Introduction Lutra lutra, the Eurasian otter, is widespread in tropical Asia, and the subspe­ cies, L. lutra nair, occurs in Sri Lanka and South India (Phillips, 1984). The avail­ able information on the food of L. lutra in the tropical Asia is limited. In Sri Lanka, however, it*Ls known to feed mainly on crabs (de Silva, 1996) but fish and anurans are also important components of the diet. Insects, water snakes, birds and mammals are also eaten, but are not important components of the diet. In Thailand, it was shown to feed mainly on fish and amphibia, although some crabs, prawns, large spiders and insects were also taken (Kruuk, et al., 1994). Seasonal preferences of L. lutra to different prey items have been demon­ strated in Europe (Weir & Bannister, 1973; Adrian & Delibes, 1987; Kruuk et al., 1987; Kruuk & Moorhouse, 1990; Weber, 1990). Although there are no clear cut seasonal differences in tropical countries such as Sri Lanka, which is an island located at 6°-10°N, 80°-82°E, the monsoons do confer, through water level fluctuations and flooding, some seasonality with respect to the rainfall to tropi­ cal freshwater ecosystems (Lowe-McConnel, 1987). This seasonality could be seen in some ecological and biological processes such as the reproduction of species and has been shown in the breeding of some fish species in Sri

^Department of Zoology, University of Peradeniya, Peradeniya, Sri Lanka. d e Silva

Lanka (de Silva, 1994). How such rainfall seasonality affects the prey capture of L. Ultra was investigated in the present study. Study Areas After a preliminary study of several-areas, three were selected for the long­ term study primarily because of the regular availability of spraints (faeces) in them, two were on a stream in the Mahaweli river system, the third on the Deduru river system (Fig. 1.). In the Mahaweli river system, Sarasavi Oya ("oya" means stream in Sinhala) was selected in which there were two groups of ot­ ters. This stream, about 12 km long, originates as several branches in the hills about 3,000 m asl and joins the Mahaweli river (Fig. 1A) at an elevation of about 480 m. The lower 0.5 km has a sandy substratum with scattered rocks and pebbles (in the present study, this area will be referred to as the lower part of the stream), whereas the region above this for about 1 km is rocky with large boulders. Above the region of boulders, the stream consists of several branches. For about 1 km , the substratum of these branches is sandy or peb­ bly with scattered boulders, and this stretch will be referred to as the middle part. The upper part of the stream is very steep and is mainly rocky with ex­ posed bed-rock in some parts. One group of otters inhabited the middle part of the stream but did not appear to venture below the region of boulders to the lower part or above the region to the upper part of the stream, as indicated by the absence of spraints in the region of boulders and the upper part. This group inhabiting the middle part of the stream will be referred to as the Sarasavi otters. The second group, in the main river of Mahaweli about 1.5 km down­ stream from the mouth of Sarasavi stream, will be referred to as the Mahaweli otters. They moved upstream to the lower part of Sarasavi stream for feeding but did not move beyond the region of boulders. Spraints were found in the lower and the middle parts of Sarasavi stream but not in the boulder-strewn part separating them or in the upper part. The large boulders in the rocky area separating the middle and lower parts of the stream may have acted as a de­ terrent to the movements of the two groups. The third group, the Kospothu otters, inhabited a stream called Kospothu Oya in another river basin. This stream (Fig. IB) originates at about 300 m asl and joins others at lower eleva­ tions to form the main tributary of the Deduru river. The stream flows through much less steep areas compared with the Sarasavi stream, and has a substra­ tum which is sandy or muddy with sparsely scattered boulders. The upper part of Sarasavi stream flows through forest, the middle part through a village, and the lower part along with part of the Mahaweli river in which the second group of otters lived bordered the university community and the township of Peradeniya. The area of Kospothu Oya in which the otters lived was surrounded mainly by rice fields, beyond which were villages. Ex­ cept for its use by the village, Sarasavi was mostly an undisturbed stream, whereas Kospothu was used regularly by a large number of villagers for bath­ ing and washing clothes, and for obtaining water for rice cultivation. Mar­ ginal vegetation consisting of Lagenandra sp. and Colocasia sp. was common in Kospothu. Although Lagenandra and Colocasia were common in the upper and middle parts of Sarasavi, the lower part did not contain such vegetation ex­ cept for a few patches of Colocasia.

206 J. South Asian nat. Hist. S e a s o n a l fo o d h a bit s o f o tter

Figure 1. Map of study areas. A. Sarasavi stream; B. Kospothu stream. Sampling areas (s-Sarasavi otters; m-Mahaweli otters; k~ Kospothu otters) are indicated by boxes. (Note the location of the holt of Mahaweli otters labelled "L").

The study areas received rains nearly every month (Fig. 2), with more in the area of Sarasavi than in the area of Kospothu. January to March is rela­ tively drier, occurring in the latter part of the NE monsoon and the beginning of 1st inter-monsoon (Fig. 2). During April to June there are convective rains from the 1st inter-monsoon and advective rains from the SW monsoon. July to September is also a relatively drier period in the latter part of SW monsoon and the beginning of 2nd inter-monsoon. October to December is usually the main rainy period and receives convective rains from the latter part of 2nd inter-monsoon and advective rains from the first part of NE monsoon. (How­ ever, in Sarasavi area in 1989, more rains fell during May-July than during October to December (Fig. 2)). The average depth of water in the sampling station for the Mahaweli otters averaged 20-30 cm during most of the months of the year, while that of the sampling station for the Sarasavi otters was less. The average depth of water in the sampling station for the Kospothu otters remained between 30-40 cm (Fig. 2).

Vol. 2., No. 2. 207 d e S ilv a

Figure 2. Rainfall and the mean depth of water at the three sampling stations during the sampling period. A-Mahaweli and Sarasavi sampling area (Average depth is shown only for Mahaweli sampling area); B-Kospothu sampling area.'Note the months falling in monsoonal and inter-monsoonal periods). Materials and methods In each sampling locality, a stretch of about 500 m was examined weekly and fresh spraints collected. Weekly samples from each habitat usually numbered 10 or more samples. These were oven-dried at 60°C for 24 hours and weighed to the nearest 1 mg. Remains of various food items were carefully picked out from the sample and separated into different categories, which were weighed also to the nearest 1 mg separately. The relative abundance of food items was estimated from the dry weights. The percentage frequency of occurrence of a particular food item was esti­ mated as the proportion of samples in which it occurred with respect to the total number of samples. The monthly percentage frequencies of major food items (crab, fish and frog) from different habitats were compared using the non-parametric Wilcoxon's Two Groups test to determine whether there are differences in the relative utilisation of these food items in different habitats. The percentage frequencies of occurrence of the major food items (crab, fish and frog) in spraints showed some differences during some months. There­ fore, data were grouped into intervals of three months (January-March, April- June, July-September and October-December) and analysed statistically using the Wilcoxon's Two Groups test in order to determine whether the importance of individual food items differed seasonally (quarterly) in each habitat.

208 J. South Asian nat. Hist.