Reproductive Behaviour of Chlorocyphidae. Part 1. Genus Sclerocypha Fraser, 1949 (Odonata)

Reproductive behaviour of genus Sclerocypha 1st December 2019285 Reproductive behaviour of Chlorocyphidae. Part 1. Genus Sclerocypha Fraser, 1949 (Odonata) André Günther Naturschutzinstitut Freiberg, B.-Kellermann-Str. 20, 09599 Freiberg, Germany; <[email protected]> Received 25th September 2019; revised and accepted 10th October 2019 Abstract. The reproductive behaviour of the damselfly Sclerocypha bisignata (Chlorocyphi- dae) was studied in various fast flowing streams in mountainous regions of Central Sulawesi. Using high speed cinematography males were shown to exhibit protracted threatening flights with a stationary display of the fore wings. In steady threatening flight the abdomen was held horizontally and the stroking of the hind wings paused briefly and regularly every 2−5 wing beats. These flights were interrupted periodically by short bursts of increased intensity were males arched their abdomens upwards and the hind wing beat was continuous. This flight style differs in several respects from any chlorocyphid species yet studied. During courtship the males presented all three pairs of legs; as courtship intensified they briefly raised their abdomen and presented stationary fore wings. Oviposition took place with the female completely submerged. Unlike most Chlorocyphidae, oviposition sites and male display sites were well separated and ovipositing females were unguarded. Further key words. Zygoptera, Sclerocypha bisignata, Libellago, threat display, courtship, stationary wing display, mating systems, Sulawesi Introduction The Indonesian island of Sulawesi hosts an extraordinarily rich fauna of the family Chlorocyphidae (Ris 1916; Fraser 1949; van Tol 1998, 2007; van Tol & Günther 2018). Three monotypic, endemic genera are known from the island: Disparocypha Ris, 1916, Sclerocypha Fraser, 1949, and Watuwila van Tol, 1998. Very little has been published on the biology and ecology of the three species of these genera. The present paper describes for the first time the behaviour of Sclerocypha bisignata (McLachlan, 1870), based on field studies in Central Sulawesi. It forms the first in a series of reports on the behaviour and ecology of various Chlorocyphidae in the Australasian, Indo-Malayan and Afrotropical regions. In many chlorocyphid species males defend small territories around high quality oviposition sites, monopolizing this resource (e.g., Robertson 1982; Odonatologica 48(3/4) 2019: 285-304Odonatologica – DOI:10.5281/zenodo.3539742 48(3/4) 2019: 285-304 286 A. Günther Orr 1996). This is the primary basis for a general pattern of reproductive behaviour which gives rise to a variety of mating systems. These systems are influenced by the population density of the species and the temporal stabil- ity of the habitats and resources (Günther 2008). Species recognition seems to be primarily based on visual sig nals (e.g., Robertson 1982; Orr 1996; Günther 2008; Karjalainen & Hämäläinen 2013). Males of most species are brightly coloured and richly ornamented either on the body or the wings or on both (Orr 1996). They exhibit highly complex and ritualized, species specific threat and courtship behaviour. Several studies have shown that there is a close connection between the colouration of the body, wings and legs and their presentation in threatening flights as well as in courtship display (e.g., Robertson 1982; Rudolph 1993; Orr 1996, 2009; Telford et al. 1996; Günther 2008). Studies in tropical Southeast Asia and New Guin- ea of coloured-winged chlorocyphids (Orr 1996; Günther 2008) revealed highly specialized flight patterns associated with the presentation of their coloured wings, including stationary presentation of wings, pauses in wing beating, simultaneously presenting the under surface of all wings, or alter- nating wing beat rate with bursts of intensified frequency. As summarized by Orr (1996), the agonistic and courtship displays of Chlorocyphidae »in- clude both morphological and behavioural components: i.e., ornaments per se and the actions which reveal them«. The possible evolutionary origins of wing ornamentation and displays are suggested by the clear-winged African chlorocyphid Chlorocypha cancellata (Selys, 1879). Males of this species exhibit context and behaviour dependent changes in the wing beat frequency, suggesting that chlorocyphid species with clear wings can use specialized flight modes for intraspecific signallingGünther ( 2015). In contrast to the males, the females are usually cryptically coloured and behave very incon- spicuously. In most species the females have unmarked, hyaline wings. Ovi- position generally takes place in dead plant material near the water surface, but the range of oviposition sites varies from fully submerged up to high over the water on mossy logs and dead wood (e.g., Orr 1996; Günther 2008). Group oviposition is common (e.g., Martens & Reh feldt 1989; Orr 2009). Sclerocypha bisignata is a large chlorocyphid with long, slender and mostly hyaline wings (Fig. 1). In the males the tips of the fore wings have opaque markings, as in many Libellago species, with some blue iridescence visible at Odonatologica 48(3/4) 2019: 285-304 Reproductive behaviour of genus Sclerocypha 287 certain viewing angles. The fore wing of the male has no pterostigma. The costa of the fore wing is thickened and coloured red over about three cells anterior to the nodus. Proximal to the nodus the fore wings have a trans- verse opaque to semi-opaque brownish black patch, with blue reflections in the opaque areas. The hind wings are without these dark markings but in older males, both pairs of wings develop a light brownish tint. In the males the thorax is generally black with yellow and orange markings and the abdomen is predominantly red. The legs are black with extensive white markings on the inner sides of tibiae and femora. Sclerocypha females are inconspicu- ously coloured and without wing markings. The species was described as Micromerus bisignatus by McLachlan (1870) and later placed by Fraser in the monotypic genus Sclerocypha Fra- ser, 1949. Van Tol (2007) revised Sclerocypha together with the probably closely related Sulawesian species of the genus Libellago Selys, 1840, but re- tained its status as a separate genus. Sclerocypha bisignata is endemic to Sulawesi and has been found mainly »in the mountains of Central Sulawesi, southwards to the Latimojong area« (van Tol 2007). Furthermore van Tol (2007) notes: »One 19th century Figure 1. Sclerocypha bisignata, male. Stream Sg. Torau northwest of Danau Poso, Sulawesi Tengah, Indonesia. Photo: AG (08-xii-2018) Odonatologica 48(3/4) 2019: 285-304 288 A. Günther record from the Togian islands. Remarkably, the type was collected near Tondano in the eastern tip of the northern peninsula. Only one other specimen is known from the northern arm of Sulawesi, from exactly the same lo- cality. Collecting in this area by Coomans de Ruiter, a collector of many un- common species of Odonata, never revealed another specimen«. Searches for the species in the Tondano area by Jan van Tol in January 1989 (van Tol 2007 and pers. comm.) and by me in August 2011 as well as on the Togian islands in 1994 and 1999 by me were all unsuccessful. Some additional and more recent records from Central Sulawesi were published by Günther (2008), Hoess (2014) and Benstead (2017). Material and methods Study area The main study area was the mountainous area northwest of Danau Poso. During the 1990s, the area along the road to Gintu (west of Danau Poso) was Figure 2. Stream Sg. Torau, Sulawesi Tengah, Indonesia. Habitat of Sclerocypha bisignata, Disparocypha biedermanni and Rhinocypha phantasma. Photo: AG (09- -xii-2018) Odonatologica 48(3/4) 2019: 285-304 Reproductive behaviour of genus Sclerocypha 289 still largely covered by more or less virgin forest. In 2018, large parts of the area were designated as a settlement area. Deforestation took place especially in the vicinity of the streams, now dominated by clearings and plantations. Most observations were made at Sungai (Sg.) Torau just above the road from Tentena to Gintu (1.791861°S, 120.504306°E; 1 029 m a.s.l., Fig. 2). This fast flowing, steep stream averaged about 3–4 m in width but frequent- ly divided into two to three streamlets. The substrate was stony with many large stones and rocks. The water was clear without dystrophic brown tint- ing. Vegetation was mostly absent in the stream except for some mosses, ferns and seedlings on large emergent stones. The banks in the study section supported disturbed primary forest. The source of the stream is in forest but there was a small, recently cleared area upstream of the observation point. Methods Reproductive behaviour was observed and filmed from 08–12-xii-2018 at Sg. Torau. Further behavioural observations were made on March 1993 and July/August 1994 (see Table 1). Latitude and longitude coordinates are given in decimal degrees (WGS84) and were taken with a handheld GPS device Garmin Oregon 450t (2018) or derived from Google EarthTM (1993/94). The water temperatures were measured with a digital thermometer, the pH with Czensny indicator. Behaviour was monitored from the morning when the males arrived at their territories, until afternoon when reproductive activity ceased. On most observation days this was about 15:00 h solar time as sunlight disappeared from the stream section. Analysis of behaviour was assisted by extensive video footage. I used a Casio EX-F1 camera (Casio Computer Co., Japan) to record S. bisignata in flight at 600 f/s with sufficient resolution for single- frame analysis. For methodological details see Günther et al. (2014). The recordings were analysed with QuickTime Player version 7.7.8 (Ap- ple, Inc., USA). To obtain the wing beat frequencies I counted sequential frames separated into down stroke, up stroke and wing beat pauses. To min- imize errors some problematic recordings were analysed at least twice. In order to calculate the wing beat frequency the exposure rate (number of frames per second) was divided by the number of frames per wing beat.

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