Biology of the Afrotropical Sepedonella nana (Diptera: Sciomyzidae), whose larvae feed only on freshwater Aulophorus furcatus (Oligochaeta: Naididae)

Abstract

All studies during the last six decades have stated that sciomyzid larvae are strictly malacophagous. However, the Afrotropical sciomyzid Sepedonella nana species was found in this study to feed only on the small freshwater oligochaete, Aulophorus furcatus. The divergent oligophagous feeding behaviour of this species was investigated. The physical attributes of the egg, first-, secondand third-instar larvae, and the puparium are described. Four types of sensilla—coeloconicum, trichodeum, chaeticum, and styloconicum—are present with a characteristic distribution on each tagma. Each thoracic segment is distinguished by presence of a pair of Keilin’s organ on ventral surface. Each abdominal segment has eleven pairs of the same sensilla types; their variable locations are presented. Population dynamics of the adults are shown from our field investigations in permanent and temporary freshwater biotopes during 1996–2008. The life cycle of the species is presented from our field observations and laboratory experiments. Among the 62 species of Afrotropical Sciomyzidae, this is the eighth species for which life-cycle is entirely resolved.

A phylogenetic analysis of Sciomyzidae (Diptera) and some related genera

“…The monophyly of Sciomyzidae is based primarily on their malacophagy (although three recently studied larvae attack freshwater Oligochaeta (Knutson and Vala, 2011; Vala and Gbedjissi, 2011) and the presence of a serrate ventral arch articulated with the lower margins of the mouth hooks in the larvae. In our study, 61 species from seven nominate families (Coelopidae, Dryomyzidae, Helcomyzidae, Heterocheilidae, Huttoninidae, Phaeomyiidae and Sciomyzidae) belonging to Sciomyzoidea were analysed allowing for a test of monophyly of Sciomyzidae and the identification of the sciomyzid sister group among the six groups that have been considered its closest relatives in the literature.…”

“…The unique larval host association of Pelidnoptera nigripennis is recorded for only one of the five known species, so it is possible that the distinctive differences in larval mouthparts might be restricted to this single, highly specialized trophic behaviour. More- over, specialization on snails as hosts may not be as general as once believed for Sciomyzidae; some larvae attack freshwater Oligochaeta (Vala et al, 2000;Vala and Gbedjissi, 2011) or may be saprophagous (Foote et al, 1960). Marinoni and Mathis (2000) and Barker et al (2004) carried out cladistic analyses of morphological characters using Phaeomyiidae as the outgroup.…”

Life-cycle of the Afrotropical snail-killing flySepedon (Parasepedon) ruficepsBecker, 1923

“…This scenario is similar to the "wasteful feeding" re ported in many circumstances for the larvae of some sciomyzids reared in the presence of a surfeit of molluscs (Eckblad 1976;Valley & Berg 1977;Vala 1989). If this significant oligophagous feeding behaviour is alternative for S. ru ficeps, it is obligatory for the sciomyzids Sepedonella nana Verbeke, 1950(Vala & Gbedjissi 2011 and Sepedon (Parasepedon) knutsoni Vala, Gbedjissi and Dossou, 1994, described from Benin (Vala et al 2002). Both of these species are known only from the Afrotopical Region.…”

“…Currently available publications concern the following: the life-cycle of Sepedon hispanica hispanica Loew, 1862, larvae of which are parasitoids/predators of freshwater snails; a description and some drawings of the third instar larva and pupa of Sepedon ruficeps Becker, 1923 and S. (P.) scapularis Adams, 1905(Knutson et al 1967; the life-cycle of S. (P.) neavei Steyskal, 1956 andS. testacea Loew, 1862, larvae of which are polyphagous predators of the freshwater molluscs Physa, Biomphalaria, Lymnaea and Planorbis (Barraclough 1983); lifecycle and biology of S. (P.) trichrooscelis Speisser, 1910, larvae of which are strictly parasitoids/saprophages of the semi-terrestrial aquatic snails Succineidae (Vala et al 1995); and life-cycle of Sepedonella nana Verbeke, 1950, larvae of which attack and eat strictly the freshwater oligochaete Aulophorus furcatus (Müller) (Naididae) (Vala & Gbedjissi 2011). We must include the life-cycle of Hydromya dorsalis (Fabricius, 1775), which is a Palaearctic species, also collected in the south of Egypt.…”

New Data about Snail-Killing Flies (Diptera, Sciomyzidae) in Iran

“…Sciomyzidae (commonly called snail-killing fl ies or marsh fl ies) with about 550 declared species and 63 genera belonging to three subfamilies (Phaeomyiinae, Salticellinae and Sciomyzinae), is a moderately small family of acalyptrate fl ies (Steyskal, 1965;Barnes, 1980;Vala, Gbedjissi, 2011;Vala et al, 2012). Only Sciomyzinae (Sciomyzini and Tetanocerini) and Salticellinae occur in Iran (Tirgari, Massoud, 1979;Ayatollahi, 1971;Knutson et al, 1973;Yano, 1978;Vala, Leclercq, 1981;Rozkošný, 1987;Khaghaninia et al, 2016).…”