Objective:

To describe the taxonomic diversity and altitudinal distribution of the Chironomidae family along the Gaira River (the Sierra Nevada de Santa Marta).

Methodology:

We sampled Chironomid assemblages at three sites along an altitude gradient (60, 900, and 1700 masl) between 2018 and 2019, covering the dry and rainy periods (eight samplings in total). Samples were taken with a Surber net on the gravel and sediment substrates, and by manual collection on the litter and stone substrates. A total of 1319 larvae were collected, and distributed in 3 subfamilies (Chironominae, Orthocladiinae, and Tanypodinae) and 14 genera.

Results:

The Orthocladiinae subfamily presented the highest abundance (58,8%), followed by Chironominae (37,8%) and Tanypodinae (3,33%). La Victoria station (900 m) presented the highest number of individuals (708) and the highest number of genera (12), while La Cascada station (1,700 masl) showed the lowest abundances (221 individuals) and the lowest gender richness (8). The genera with the highest abundance were Cricotopus, Onconeura, Parametrionecmus, and Polypedilum, while Chironomus, cf. Manoa, and Riethia showed lower abundances in the study.

Scope:

We describe for the first time the occurrence of 14 genera in Northern Colombia.

Conclusions:

The results of this research contribute to the recognition of the diversity of chironomids in the department of Magdalena and provide additional evidence to state that the Sierra Nevada de Santa Marta is an important reservoir of biodiversity that has been little explored.

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