Chironomidae (Insecta: Diptera) of Ecuadorian high-altitude streams: a survey and illustrated key
Keywords:
non-biting midges, high Andes, Neotropical, Antisana volcano, glacier-fed streams, non-glacial streamsAbstract
Chironomidae (Diptera) are among the most diverse and widespread aquatic insects, with roughly 5,500 described species inhabiting an enormous variety of aquatic ecosystems, ranging from moist soils to lakes and rivers, and even marine ecosystems. Despite its ubiquity, the group remains underrepresented in studies addressing aquatic insect assemblages of high-altitude systems, either glacier-fed or non-glacial, particularly in South America. Glacier-fed streams possibly are one of the harshest ecosystems in nature, and present a distinct downstream pattern in species distribution and diversity away from the constraining influence of the glacier. In this context, the goal of our study was to provide data on the chironomid fauna of glacier-fed streams, together with neighboring non-glacial streams in Ecuador, in order to contribute to the overall knowledge of tropical fauna in high Andean regions. Also, we sought to provide an identification key and photography material for future studies. Collections of non-biting midges were made in Ecuador during Jan 2008. In total, 1,412 specimens belonging to 16 genera and at least 23 species within the subfamilies Chironominae (3 taxa), Diamesinae (3 taxa), Podonominae (3 taxa), Orthocladiinae (13 taxa), and Tanypodinae (1 taxon) were found. The subfamilies Podonominae and Orthocladiinae predominated in terms of abundance. Parochlus was the most widespread genus of Chironomidae, while Cricotopus was the most diverse. This study contributes to the knowledge of the chironomid fauna in the high-altitude streams in Ecuador, and hopefully will motivate further studies in the area.
Resumo
Chironomidae (Diptera) estão entre os mais diversos e difundidos insetos aquáticos, com cerca de 5.500 espécies descritas, habitando uma enorme variedade de ecossistemas aquáticos, desde solos úmidos, lagos e rios, até mesmo ecossistemas marinhos. Apesar de sua onipresença, o grupo continua sub-representado em estudos que abordam assembléias de insetos aquáticos de sistemas de alta altitude, seja de origem glacial ou não, particularmente na América do Sul. Riachos glaciais são possivelmente um dos ecossistemas mais severos da natureza e, portanto, apresentam tipicamente um padrão espacial distinto na distribuição e diversidade das assembleias de espécies a jusante e longe da influência limitadora da geleira. Neste contexto, o objetivo do nosso estudo foi fornecer dados sobre a fauna de Chironomidae de alguns riachos glaciais e não-glaciais no Equador, a fim de contribuir para o conhecimento global da fauna tropical nas regiões andinas de alta latitude, além de fornecer uma chave de identificação e um catálogo fotos para futuros estudos. Durante o mês de janeiro de 2008, as coletas de Chironomidae foram realizadas no Equador. No total, 1.412 espécimes pertencentes a 16 gêneros e pelo menos 23 espécies pertencentes às subfamílias Chironominae (3 táxones), Diamesinae (3 táxones), Podonominae (3 táxones), Orthocladiinae (13 táxones) e Tanypodinae (1 taxon) foram encontrados. As subfamílias Podonominae e Orthocladiinae predominaram em termos de abundância. Parochlus foi o gênero mais difundido, enquanto Cricotopus o mais diversificado. O presente estudo contribui para o conhecimento sobre a fauna de Chironomidae nos córregos de alta altitude no Equador e espera-se que motive estudos adicionais na área.
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- Fig. 2. Manoa sp.: a) Head capsule, ventral view. b) Labrum-epipharyngis. c) Antennas. d) Mentum, mandibles and ventromental plates. e) Posterior parapods and anal tubules, lateral view.
- Fig. 1. Map of the Antisana stream system. For site codes see Tab. 1-2. Glaciated area is marked with grey. Sites 1–10 are glaciated, sites 11–17 are non-glacial.
- Fig. 3. Tanytarsus sp.: a) Mandible. b). Mentum and ventromental plates. c). Labro-epipharyngeal region (showing premanidibles with 3 teeth). d) Head capsule, ventral view.
- Fig. 4. Limaya sp.: a) Mandible. b) Mentum. c) Antenna. d) Labro-epipharyngeal region.
- Fig. 5. Paraheptagyia sp. A: a) Head capsule, dorsal view. b) Mentum and mandibles. c). Head capsule, ventral view. Arrow indicates occipital margin.
- Fig. 6. Paraheptagyia sp. B: a) Mentum. b) Mandibles. c) Anal end of body, lateral view. d) Head capsule, ventral view. Arrow indicates occipital margin.
- Fig. 7. Parochlus sp. A: a), e). Anal end with posterior parapods, procercus and anal setae. Lateral and dorsal view. b) Mentum and mandibles. c) Claws of posterior parapods (note the two types of claws indicated by arrow). d) Antenna.
- Fig. 8. Parochlus sp. B: a–c) Anal end with posterior parapod, procercus and anal setae, lateral (a, b) and dorsal view (c).
- Fig. 9. Podonomus sp.: a) Anterior parapod with fan shaped arrangement of claws, lateral view. b–c) Anal end with posterior parapod, procercus and anal setae, dorsolateral view. d) Larvae under low magnification.
- Fig. 10. Corynoneura lobata group: a) Antenna. b) Mentum, mandibles and labro-epipharyngeal region. c) Head capsule, dorsolateral view.
- Fig. 11. Cricotopus sp. A: a) Labro-epipharyngeal region. b) Body. c) Body setation. d) Head capsule, ventral view. e) Mandible. Arrow shows position of seta submenti.
- Fig. 12. Cricotopus sp. B: a) Mandible. b) Head capsule, ventral view. c) Mentum. d) Body segment with seta. Arrow shows position of seta submenti.
- Fig. 13. Cricotopus sp. C: a) Mandible. b) Head capsule, ventral view. c) Mentum. Arrow shows position of seta submenti.
- Fig. 14. Cricotopus sp. D: a) Mentum. Arrow indicates the reduced 2nd lateral tooth. b) Mandible. c) Head capsule, ventral view.
- Fig. 15. Limnophyes sp.: a) Anal end of body, anal tubules are indicated by arrow. b) Antenna and mandible, arrow indicates long antennal blade. c) Mentum with wedge shaped tubercle (indicated by arrow).
- Fig. 16. Metriocnemus eurynotus group: a) Mandible. b) Antenna. c) Mentum. d) Head capsule, ventral view.
- Fig. 17. Metriocnemus fuscipes group: a) Antenna. b) Mandible. c) Mentum.
- Fig. 18. Onconeura sp.: a) Head capsule. Arrow indicates antenna. b) Mentum and mandible. c) Antenna. d) Body segments with strong setation.
- Fig. 19. Orthocladius (Euo.) sp.: a) Mentum. b) Head capsule, ventral view. c) Detail of occipital margin. d) Antenna and madible.
- Fig. 20. Parakiefferiella sp.: a) Mandible. b) Antenna. Arrow indicates vestigial 6th segment. c) Mentum.
- Fig. 21. Pseudosmittia sp.: a) Head capsule, ventral view. b) Anal end, ventral view. c) Mentum and mandible.
- Fig. 22. Smittia sp.: a) Head capsule, ventral view. b) Mentum. c) Basally fused anterior parapods, with two types of claws (fine spines are indicated by arrow), lateral view. d) Posterior parapods (detail), ventral view. Arrow indicate a row of minute cl
- Fig. 23. Pentaneura sp.: A. Head capsule, ventral view. B. Ligula and paraligula. C. Maxillary palp with sensilla. D. Anal end of body.
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