A constellation of fungus gnats (Diptera: Keroplatidae and Mycetophilidae) from caves of the Parc Natural dels Ports, Tarragona, Western Catalonia

Abstract

A constellation of fungus gnats (Diptera: Keroplatidae and Mycetophilidae) from caves of the Parc Natural dels Ports, Tarragona, Western Catalonia
A preliminary approximation of the fungus gnat fauna (Diptera: Keroplatidae and Mycetophilidae) is presented, captured in caves of the Parc Natural dels Ports (Tarragona, Catalonia) following surveys conducted in the massif in 2012. We report a total of 11 species from ten prospected caves and provide data on the biology and images where possible. Exechiopsis coremura (Edwards) stands out due to few previous records of this species in the Iberian peninsula.

Key words: Cave Habitats, Diptera, Mycetophilidae, Keroplatidae, Ports, Catalonia

Resumen

Una constelación de moscas de los hongos (Diptera: Keroplatidae y Mycetophilidae) de cuevas del Parc Natural dels Ports, Tarragona, Cataluña occidental
Se presenta una primera aproximación a la fauna de moscas y mosquitos de los hongos (Diptera: Keroplatidae y Mycetophilidae) recolectada en las cuevas del Parc Natural dels Ports (Tarragona), como resultado de las prospecciones realizadas en el macizo durante el año 2012. Se citan un total de 11 especies recolectadas en las 10 cuevas prospectadas y, cuando es posible, se ofrecen datos sobre su biología así como imágenes de las especies citadas. La especie Exechiopsis coremura (Edwards) destaca especialmente debido a las escasas citas de la misma en la península Ibérica.

Palabras clave: Hábitat cavernícola, Diptera, Mycetophilidae, Keroplatidae, Ports, Cataluña

Resum

Una constel·lació de mosques dels fongs (Diptera: Keroplatidae i Mycetophilidae) de coves del Parc Natural dels Ports (Terra Alta, Baix Ebre, Montsià), Catalunya Occidental
Es presenta una primera aproximació a la fauna de mosques i mosquits dels fongs (Diptera: Keroplatidae i Mycetophilidae) recol·lectada a les coves del Parc Natural dels Ports (Terra Alta, Baix Ebre, Montsià), com a resultat de les prospeccions practicades al massís durant l’any 2012. Se citen un total d’11 espècies recol·lectades a les 10 coves prospectades i, quan és possible, s’ofereixen dades sobre la seva biologia i imatges de les espècies esmentades. L’espècie Exechiopsis coremura (Edwards) destaca especialment perquè ha estat molt poc citada a la península Ibèrica.

Paraules clau: Hàbitat cavernícola, Diptera, Mycetophilidae, Keroplatidae, Ports, Catalunya

Introduction

Fungus gnat families (Keroplatidae and Mycetophilidae) in the Iberian peninsula include approximately 261 species (Chandler & Báez, 2002). They are mainly found in forest or wooded areas where they develop in fruiting bodies of large fungi or in rotting wood, with a few species developing in bryophytes and bird nests (Chandler, 2004). Keroplatidae larvae mostly live in slimy webs that they produce underneath the fruiting bodies of polypores or on dead wood (Evenhuis, 2006), although the larvae of some species are predaceous (Jakovlev & Siitonen, 2004). Mycetophilidae larvae usually develop inside fungal fruiting bodies, under bark, in sporophores, or on hyphae penetrating decaying wood or rotting organic matter and other plant material, above all in dead wood (Gammelmo & Søli, 2006; Søli et al., 2009).

Adults of both families are often found in dark, damp places (e.g. caves), resting under fallen decaying logs, wet rock shelters, and similar. Fungus gnat fauna from caves, mines and other cave systems in Europe has been widely studied (e.g. Tollet, 1955, 1959; Burghele-Balacesco, 1965, 1966, 1972; Hutson, 1978, 1980; Østbye et al., 1987; Plassmann & Weber, 1988; Weber et al., 2007), and with some exceptions, most of these species are considered trogloxenes, occupying the caves during the hibernation period (Kjaerandsen, 1993).

In 2012, staff of the Arthropods Department at the Museu de Ciències Naturals de Barcelona (MCNB) and the Societat Catalana de Bioespeleologia (Catalan Biospeleology Association, BIOSP) conducted a series of surveys in the Parc Natural dels Ports (Tarragona, western Catalonia) with the aim of studying the arthropod fauna present in the caves of this limestone massif (fig. 1). This 35,050 hectare natural park has 28% of its surface above 1,000 m altitude, reaching its peak of 1,441 m in the Caro mountain. The park has over 200 species of vertebrates and 1,370 taxa of vascular flora, with red pine forest (Pinus sylvestris Linnaeus) being the most abundant, occupying 32.4% of the territory (fig. 2). Despite the scientific community’s interest in this park for its scenic and natural value and conservation status, very little is known about existing arthropod fauna, and attention has focused on very specific groups (e.g. Coleoptera and Lepidoptera) and species of special interest or endangered.

Fig. 1. Parc Natural dels Ports (Tarragona, western Catalonia) and location of the 10 prospected caves (see Material and methods).
Fig. 1. Parc Natural dels Ports (Tarragona, Cataluña Occidental) y localización de las 10 cuevas prospectadas (ver Material y métodos).

Fig. 2. An exechiine (tribe Exechiini) in Avenc dels Mamelons, possibly an Exechia species, a representative of the arthropod fauna studied in 2012 (A), and the red pine forest, the most abundant tree species in the park (B).
Fig. 2. Un micetofílido (tribu Exechiini) en el Avenc dels Mamelons, posiblemente de la especie Exechia, un representante de la fauna de artrópodos estudiada en 2012 (A), y el bosque de pino rojo, el árbol más abundante en el parque (B).

As a result of a survey of 10 caves with wide diversity in their topology and development, 10 species of seven genera of the family Mycetophilidae and one species of Keroplatidae were collected. We offer a portrait of all these species and their distribution in the studied caves.

Material and methods

The specimens were captured using several sampling methods both at the entrance to the caves and in the interior. We combined direct capture by entomological net and traps with attractant or bait (cheese and dried meat combined). Samples were preserved in 70% EtOH and are deposited in the general collection at MCNB. We used a Motic Stereomicroscopy SMZ-168 and all the images (field and lab) were taken with an iPhone4.

During the study a total of 10 caves were examined (fig. 1): 1. Avenc Ermets de Passamonte; 2. Cova del Conill; 3. Avenc del Sabarín; 4. Forat del Riu Algars; 5. Avenc del Polit (without samples); 6. Avenc dels Mamelons (without samples); 7. Avenc de la Crisi; 8. Avenc del Salany (without samples); 9. Avenc de la Barcina (without samples) and 10. Cova Trobada. Specimens were found in six caves (1, 2, 3, 4, 7 and 10) but not in the remainig four (5, 6, 8 and 9).

Results and discussion

During the preliminary sampling from April 19 to August 31 of 2012, a total of 107 specimens were obtained: a single specimen of Keroplatidae, belonging to the species Macrocera fasciata Meigen (fig. 3A), and 106 specimens of Mycetophilidae, distributed among 10 species: Exechia fulva Santos Abreu (fig. 3B), Exechiopsis (Exechiopsis) coremura (Edwards) (fig. 3C), Exechiopsis (Exechiopsis) jenkinsoni (Edwards) (fig. 4A), Exechiopsis (Exechiopsis) pseudindecisa (Laštovka & Matile) (fig. 4B), Exechiopsis (Exechiopsis) unguiculata (Lundström) (fig. 4C), Mycetophila marginata Winnertz (fig. 5A), Mycomya cinerascens (Macquart) (fig. 5B), Phronia tenuis Winnertz (fig. 5C), Rymosia affinis Winnertz (fig. 6A) and Tarnania dziedzickii (Edwards) (fig. 6B).

Fig. 3. Keroplatidae and Mycetophilidae specimens collected in the studied caves: M. fasciata (A), E. fulva (B) and E. coremura (C). We provide the status and distribution of each species, followed by the number of the cave where the species is confirmed.
Fig. 3. Especímenes de Keroplatidae y Mycetophilidae recolectados en la cuevas estudiadas: M. fasciata (A), E. fulva (B) y E. coremura (C). Se indica el estatus y distribución de cada especie seguido del número de la cueva donde su presencia está confirmada.

Fig. 4. Mycetophilidae specimens sampled in the studied caves: E. jenkinsoni (A), E. pseudindecisa (B) and E. unguiculata (C). We provide the status and distribution of each species, followed by the number of the cave where the species is confirmed
Fig. 4. Especímenes de Mycetophilidae recolectados en las cuevas estudiadas: E. jenkinsoni (A), E. pseudindecisa (B) y E. unguiculata (C). Se indica el estatus y distribución de cada especie seguido del número de la cueva donde su presencia está confirmada.

Fig. 5. Mycetophilidae specimens sampled in the studied caves: M. marginata (A), M. cinerascens (B) and P. tenuis (C). We provide the status and distribution of each species, followed by the number of the cave where the species is confirmed.
Fig. 5. Especímenes de Mycetophilidae recolectados en la cuevas estudiadas: M. marginata (A), M. cinerascens (B) y P. tenuis (C). Se indica el estatus y distribución de cada especie seguido del número de la cueva donde su presencia está confirmada.

Fig. 6. Keroplatidae and Mycetophilidae specimens sampled in the studied caves: R. affinis (A) and T. dziedzickii (B). We provide the status and distribution of each species, followed by the number of the cave where the species is confirmed.
Fig. 6. Especímenes de Keroplatidae y Mycetophilidae recolectados en las cuevas estudiadas: R. affinis (A) y T. dziedzickii (B). Se indica el estatus y distribución de cada especie seguido del número de la cueva donde su presencia está confirmada.

Table 1 shows details of collection data.

Table 1. Species of Keroplatidae and Mycetophilidae in each cave, number of identified specimens and sex, collection date and registration number of each sample in the MCNB collection (Museum accessing number). Tabla 1. Especies de Keroplatidae y Mycetophilidae en cada cueva, número y sexo de los especímenes identificados, fecha de recolección y número de registro de cada muestra en la colección del MCNB (Museum accessing number).

The largest number of specimens were found at the cave entrances or within the first metre, where the cavities provide a gloomy environment. Caves with horizontal development (Ermets de Passamonte, Conill, Sabarín, Trobada) contained more specimens in deeper cavities -where there was total darkness- than caves with vertical development (Crisi, Barcina, Polit).

The Avenc del Sabarín cave had the highest number of specimens and the highest diversity, with 52 specimens from eight species. Six species were found only in this cave: M. fasciata, E. fulva, E. coremura, E. unguiculata, M. marginata, M. cinerascens and P. tenuis. One of these species, E. coremura, is of special interest for the Iberian fauna due to the scarcity of records. In findings to date it has been restricted to the western Mediterranean and its biology is unknown. Rymosia affinis showed the widest distribution in the area, being found in four of the caves.

The Mycetophilidae recorded are mostly known to develop in external fungi, either those growing on wood in the case of Mycetophila marginata and the Mycomya and Phronia species, or terrestrial agarics in the case of the Exechia, Exechiopsis, Rymosia and Tarnania species. These species enter caves for aestivation or hibernation as adults. Undoubtedly, further study directed towards this group of Diptera will increase the number of known species in the rest of the Ports caves.

The keroplatid Macrocera fasciata (fig. 3A) has been reared from larval webs under bark and in tree hollows (Jakovlev, 2011), but there are also records from webs on cellar walls. Edwards (1925) queried an earlier record from larvae said to have been feeding on fungal growth on a cellar wall (Enslin, 1906), but Laurence (1982) confirmed this occurrence when he found larval webs in a cellar, also inhabited by the cave fungus gnat Speolepta leptogaster (Winnertz) (Mycetophilidae). Laurence (ibid.) concluded that the larvae of M. fasciata were predators of adults of Speolepta that he found dead in their webs, predaceous larvae being known in some other Keroplatidae. It is feasible that M. fasciata occupies a similar niche within caves.

Acknowledgements

We thank the technical staff at the Parc Natural dels Ports for their help during the surveys and their interest in supporting and promoting this study, Glòria Masó and Berta Caballero (MCNB) for comprehensive and systematic management of the project, and members of BIOSP for their support and constant motivation during exploration and sampling, particularly Floren Fadrique and Josep Pastor. We also thank MCNB staff directly involved with sampling, reviewing and overall management of the samples: Miguel Prieto, Neus Brañas, Jordi Agulló, Mireia Nel·lo and Sergi Gago.

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