Verhandlungen der Gesellschaft für Ichthyologie Band 5, 2006, 139-163 Preliminary checklist of sailfin silversides (Teleostei: Telmatherinidae) in the Malili Lakes of Sulawesi (Indonesia), with a synopsis of systematics and threats Vorläufige Checkliste der Sonnenstrahlfische (Teleostei: Telmatherinidae) der Maliliseen Sulawesis (Indonesien), mit einer Übersicht zu Systematik und Bedrohung Fabian Herder1, Julia Schwarzer1, Jobst Pfaender1, Renny K. Hadiaty2, and Ulrich K. Schliewen3. 1 Sektion Ichthyologie, Zoologisches Forschungsmuseum Alexander Koenig, Adenauer- allee 160, D-53113 Bonn, Germany; [email protected] (corresponding author) 2 Ichthyology Laboratory, Division of Zoology, Research Center for Biology, Indonesian Institute of Sciences (LIPI), Jl. Raya Bogor Km 46, Cibinong 16911, Indonesia 3 Department of Ichthyology, Bavarian State Collection of Zoology (ZSM), Münchhausenstr. 21, D-81247 München, Germany Summary: The ancient Malili Lakes in Sulawesi harbor an adaptive radiation of sailfin silversides (Teleostei: Atheriniformes: Telmatherinidae). This radiation is characterized by local endemism either to basins of Lakes Towuti, Mahalona and Lontoa (Wawontoa) or to that of Lake Matano, and by spectacular male color polymorphisms. Based on recent surveys, we report a previously unde- tected diversity of steam-dwelling Telmatherinidae, inhabiting a wide range of the lake system’s rivers and streams and additional adjacent catchments. We provide a preliminary checklist of Telm- atherinidae in the Malili Lakes system, including surrounding catchments, and add records of three yet undescribed lacustrine Telmatherina from Lake Matano. Distribution patterns of Lake Matano’s Telmatherina are provided in detail, based on eight sampling locations around the lake’s shoreline. Moreover, we record an increased number of color morphs in five known Telmatherina and summarize color polymorphisms of the species-flock. As this radiation is used as model system to address questions concerning speciation and maintenance of color polymorphisms, we provide a summary of taxonomic, systematic, ethological and evolutionary biological knowledge regarding telmatheri- nids, give a brief overview about the environmental settings, and discuss the serious threats endan- gering this endemic ichthyofauna. Key words: Telmatherinidae, adaptive radiation, Malili Lakes system, Sulawesi, diversity, threats Zusammenfassung: Die Maliliseen Sulawesis beherbergen eine adaptive Radiation von Sonnen- strahlfischen (Teleostei: Atheriniformes: Telmatherinidae). Diese Radiation zeichnet sich durch lokalendemische Verbreitungsmuster einerseits in den Seen Towuti, Mahalona und Lontoa (Wa- wontoa) oder andererseits im Matanosee, sowie durch spektakuläre Farbpolymorphismen aus. Ba- sierend auf kürzlich erfolgten Felderfassungen stellen wir eine bislang unbekannte Diversität bach- bewohnender Telmatheriniden vor, die in weiten Bereichen der Flüssen und Bächen des Seensys- tems sowie angrenzenden Einzugsgebieten verbreitet ist. Wir stellen eine vorläufige Checkliste der Telmatheriniden des Maliliseen-Systems einschließlich umgebender Einzugsgebiete auf und fügen Nachweise von drei bislang unbeschriebenen lakustrinen Telmatherina aus dem Matanosee hinzu. Verbreitungsmuster der Manatosee-Telmatherina werden detailliert aufgezeigt, basierend auf acht Sammelstellen rings um die Uferzone des Sees. Außerdem weisen wir eine höhere Anzahl Farb- Verh. Ges. Ichthyol. Bd. 5, 2006 139 morphen für fünf bekannte Telmatherina nach und fassen die Farbpolymorphismen des Artenschwar- mes zusammen. Da diese Radiation als Modellsystem dient um Fragen zu Artbildung und Aufrech- terhaltung von Farbpolymorphismen nachzugehen, geben wir eine Zusammenfassung über den taxonomischen, systematischen, verhaltensbiologischen und evolutionsbiologischen Forschungs- stand über Telmatheriniden sowie einen kurzen Überblick über die naturräumlichen Bedingungen und diskutieren die ernsthaften Bedrohungen, die diese endemische Fischfauna gefährden. Schlüsselwörter: Telmatherinidae, Adaptive Radiation, Maliliseen, Sulawesi, Diversität, Bedro- hung 1. Introduction examinations and a sophisticated concept of recognizing “species” within this ob- Over the last 109 years a diversity of small, viously still radiating flock are required. atheriniform freshwater fishes has been described from the island of Sulawesi (In- 1.1. The Malili Lakes system donesia), accounted to the family of sailfin silversides (Atheriniformes: Telmatherin- The Malili Lakes system is located in Cen- idae). Only one out of the island’s 16 spe- tral Sulawesi (the former Celebes) (fig. 1), cies is found in streams of its south-west- consisting of five interconnected lakes. The ern branch, the remaining 15 are endemic three major lakes Matano, Mahalona and to the Malili Lakes system in Central Sula- Towuti are large, deep ancient lakes of tec- wesi (Kottelat 1990a, 1991). The chance to tonic origin (Abendanon 1915a, b, Brooks study evolution of organismic diversity 1950, Haffner et al. 2001). Lake Matano is within an outstanding, compact but diverse with 590 m the deepest lake in Southeast model system characterized by different Asia and the eighth deepest lake in the world degrees of isolation, has attracted recently (Hutchinson 1957). Geologically, it is a tec- several research groups to this system. Apart tonic graben lake of the still active Matano from sailfin silversides, the endemic inver- fault zone (Ahmad 1977). tebrate radiations of crustaceans (atyid Lakes Matano, Mahalona and Towuti are shrimps and parathelphusid crabs) and pa- arranged along a cascading chain with con- chychilid snails (von Rintelen and Glau- necting rivers. Lake Matano is a steep-si- brecht 2003; von Rintelen and Glaubrecht ded graben lake (Ahmad 1977), located 396 2005; von Rintelen et al. 2004) as well as m above sea level (fig. 1). It is drained at its the predominantly endemic diversity of dia- eastern corner by the extremely steep toms (Bramburger et al. 2004, 2006) are River Petea to L. Mahalona, descending 72 m under investigation. of altitude along the river’s total length of Aim of the present paper is to (1) summar- about 9.5 km (Abendanon 1915a, Kottelat ize present knowledge about telmatherinid 1991, own observations). According to our taxonomy, systematics and the Malili Lakes own ground checks and all accessible topo- system and (2) to provide an overview about graphic maps (1: 50.000, Lembar 2213-13, major patterns of diversity in the Malili 34) there is no major waterfall in River Lakes sailfin-silversides radiation. It is in- Petea. The river is located within a very tended as a guide to upcoming work dea- steep valley and descends along a sequence ling with evolutionary processes of this of rapids, riffles, small falls, pools and back- adaptive radiation, and to drawing attention waters until about 1 km ahead of L. Maha- to serious threats endangering this unique lona, where it becomes comparatively deep diversity. It is not aimed to serve taxono- and calm. After Lake Mahalona, the flow mic purposes, for which more detailed continues as the overall wide and slow-flow- 140 ing River Tominanga which has only one flow, Abendanon (1915b) indicated a water- series of rapids and covers a 17 m drop in fall. However, there is no indication in the elevation before reaching L. Towuti after map pointing to anything like a major water- about 8.1 km. With approximately 560 km2 fall with a drop of dozens of meters as re- of surface area, L. Towuti is the largest lake cently claimed (Roy et al. 2004). in Sulawesi (Haffner et al. 2001), but is with Brooks (1950) reviewed knowledge about 203 m less deep than L. Matano. It is drained the Malili Lakes and their species flocks and at its south-western corner to the Gulf of speculated about reasons for the patterns Bone by River Larona (= R. Malili). of their organism’s distribution. Based on The two small satellite lakes Lontoa (or Abendanon’s map, he focussed on the sep- Wawontoa; local spelling Lantoa) and Masa- arating effect of waterfalls along River pi are probably not of tectonic origin Petea, stating “…the relatively short Patea (Abendanon 1915a). According to Abenda- River which drains into Lake Mahalona de- non (1915b), the outflow of L. Lontoa is scends 72 m., part of this drop occurring located at its northern corner, draining the as waterfall.” (Brooks 1950, p. 167). lake to River Tominanga. In contrast, mod- Recent investigations of the lake’s water ern topographic maps based on aerial photo- chemistry (Giesen et al. 1991) and L. graphs show a direct connection from its Matano’s limnology (Haffner et al. 2001) southern end to L. Towuti by a small stream underpinned that all five lakes are ultraoli- (1: 50.000, Lembar 2213-13, 34). Lake Masa- gotrophic, with different levels of deficiency pi has a crater lake appearance, although in various trace elements. there is no evidence for volcanism in the area (Giesen et al. 1991). It drains to River 1.3. Telmatherinid discovery, syste- Larona, without a direct connection to the matics and evolution large lakes. Boulenger (1897) described the first sailfin 1.2. Discovery of the Lakes silverside as Telmatherina celebensis, and placed it in Atherinidae. Both syntypes originate Fritz and Paul Sarasin, two Swiss geologists from the collection by P. and F. Sarasin in and naturalists, were the first “western” visi- 1896 at Lake Towuti (see Kottelat and Sutt- tors who explored the greater area of Lake ner 1988). Based on material gathered in Matano (as “Matana”)