# Culicoides species of Palaearctic region in Afrotropical region: comments on two recent publications on Culicoides species present in Ethiopia

Denis Augot, Christine Millot, Leila Hadj-Henni

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Denis Augot, Christine Millot, Leila Hadj-Henni. Culicoides species of Palaearctic region in Afrotropical region: comments on two recent publications on Culicoides species present in Ethiopia. Parasitology Research, 2025, 125 (5), pp.49. 10.1007/s00436-025-08496-y. hal-05054201

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Distributed under a Creative Commons Attribution 4.0 International License
*Culicoides* species of Palaearctic region in Afrotropical region:
comments on two recent publications on *Culicoides* species present
in Ethiopia

Denis Augot<fnref n="1" /> Ⓓ · Christine Millot<fnref n="2" /> · Leila Hadj-Henni<fnref n="2" />

Received: 16 December 2024 / Accepted: 24 April 2025 / Published online: 2 May 2025
© The Author(s) 2025

**Abstract**

Biting midges are key vectors that can transmit different pathogens to mammals and birds. In Ethiopia, two studies showed the diversity of *Culicoides* species in several districts based on morphological characters. For this, the same identification key was used for Afrotropical and Palaearctic *Culicoides* fauna. Consequently, results are incomplete and erroneous. It is misleading to state that a universal identification key is available.

**Keywords** *Culicoides* · Identification · Ethiopia

Two studies recently published in *Scientific Reports* (Fetene et al 2022; Ayele et al. 2024) showed the species composition of *Culicoides* in several districts of Ethiopia. It is necessary to make some comments on the methodology of these studies and discuss both the results and conclusions. The first study (Fetene et al 2022) explored the factors (environmental and climatic variables) associated with the most abundant species captured (*C. imicola* and *C. kingi*) in this area. The authors reported the presence of five species and an unidentified species in southwestern Ethiopia. *Culicoides* specimens were thus identified to the species level using three keys (Khamala and Kettle 1971; Glick 1990; Mathieu et al 2012). The second study (Ayele et al. 2024) focused on the spatial distribution and seasonal occurrences of *Culicoides* species in several districts. They reported the presence of 10 species and two groups (one of unidentified species, and

the other of species similar to *C. paolae* and *C. festivipennis* in northwestern Ethiopia. The authors only used the key developed by Mathieu et al. (2012) for *Culicoides* identification. Both studies are based on samples collected with OVI traps using the same protocol (trap at a height of 1.5–2 m above the ground, with 12 h of trapping—from dusk (18:00) to dawn (06:00)—conducted from December 2018 to April 2021 in the first case and between January and July 2023 in the second case.

Currently, more than 1400 *Culicoides* species have been described worldwide (Borkent and Dominiak 2020). The taxonomy of *Culicoides* is almost entirely phenetic (i.e. based on overall similarity), so correct identification is a challenge. The morphological characters used to identify a species are the same worldwide: wings (size, spots), antenatal sensilla, palpal segments, spermathecae (shape, size, and number), the shape and form of the male genitalia, etc. Therefore, these characters have been used as the basis for developing aids to identification and dichotomous keys by species (Harrup et al 2015). Furthermore, they have been applied to a range of regional fauna based on biogeographical regions (Holt et al 2013). Ethiopia is a country in the Afrotropical region. Consequently, the keys used for correct identification must be applied to this particular biogeographical region. However, the authors (Ayele et al 2024) do not acknowledge the delineation of zoogeographic regions and use the key (Mathieu et al 2012) applicable to the Palaearctic region to identify *Culicoides* fauna from Ethiopia. The number of biting midge shared species between Palaearctic and

Section Editor: Helge Kampen.

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Denis Augot
denis.augot@anses.fr

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Christine Millot
christine.millot@univ-reims.fr

<footnote n="1">¹ ANSES, INRAE, ENVA, UMR-BIPAR, Laboratoire de Santé Animale, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort Cedex, France</footnote>

<footnote n="2">² USC Petard, ANSES LSA, EA 7510, SFR Cap Santé, Université de Reims Champagne - Ardenne, 51 rue Cognacq-Jay, 51096 Reims Cedex, France</footnote>
Afrotropical regions is very limited (Borkent and Dominiak 2020) and even more limited if we consider only *Culicoides* genus. *Culicoides* species of Palaearctic region are not reported in Afrotropical region. In contrast, only few species of Afrotropical region are present in Palaearctic region like *C. imicola* or *C. kingi*. The biodiversity of such region is well different, justifying a specific key by regions. The following *Culicoides* species of Ayele et al. (2024) are not present in Ethiopia: *C. corsicus*, *C. kibunensis*, *C. reioxi* (unknown species or misspelling), *C. kiouxi* (*riouxi* misspelled), *C. saharienines* (*sahariensis* misspelled), *C. desertorum*, *C. reithi* (*C. riethi*), *C. festipennis* (*festivipennis* misspelled), *C. paolae*, and *C. festivipennis* (wellspelled). Thus, the tables and maps are erroneous. Previous studies in Ethiopia reported the presence of 16 species: *C. coarctatus*, *C. cornutus*, *C. distinctipennis*, *C. fulvithorax*, *C. imicola*, *C. isiolensis*, *C. kerichoensis*, *C. leucostictus*, *C. milnei*, *C. neavei*, *C. nivosus*, *C. pycnostictus*, *C. schultzei* group (*Culicoides* sp. 4; *Culicoides* sp. 6), *C. similis*, and *C. sylvicola* (Glick 1990) and six species: *C. fulvithorax*, *C. imicola*, *C. isiolensis*, *C. milnei*, *C. neavei*, and *C. zuluensis* (Mulatu and Hailu 2019). The list of Fetene et al. (2022) includes *C. imicola*, *C. kingi*, *C. milnei*, *C. schultzei*, and *C. pycnostictus*. The authors used three keys (Khamala and Kettle 1971; Glick 1990; Mathieu et al 2012) and compared their specimens with species identified by Mathieu et al. (2012) certainly to confirm *C. imicola* and *C. kingi*. In Afrotropical region, in addition of previous references keys (Khamala and Kettle 1971; Glick 1990), several identification keys could be used, depending on species or group species (Fall et al 2015). The interactive identification key for *Culicoides* (IIKC; http://www.iikculicoides.net; Mathieu et al 2012) is a "multi-entry key" that is straightforward to use and gives a great deal of information concerning taxonomy with morphological characters (drawings and photos), along with species distribution by country. *Culicoides* milnei, *C. schultzei*, and *C. pycnostictus* are not included in the IIKC. In our opinion, only three species can be confirmed, i.e., *C. imicola*, *C. milnei*, and *C. pycnostictus*, because these species have been previously reported in Ethiopia (Glick 1990; Mulatu and Hailu 2019). Further investigations are needed to confirm *C. kingi* and *C. schultzei* (belonging to the *Schultzei* group, which includes eight species (Cornet and Brunhes 1994)) in Fetene et al. (2022) and *C. kingi* in Ayele et al. (2024).

In short, we disagree with the results, discussion, and conclusions of Ayele et al. (2024) on *Culicoides* species in Ethiopia, identified using a wrong identification key. While we believe that the study of Fetene et al. (2022) presents the same bias, the *Culicoides* species found are consistent with species present in this area. Therefore, we encourage our colleagues to use specific morphological keys and/or to contact

taxonomists with specific expertise on *Culicoides* in order to guarantee the identifications so as to present robust results.

**Author contribution** Conceptualization: DA, CM, LHH. Writing-Original draft preparation: DA. Writing-Review and Editing: DA, CM, LHH. All authors read and approved the final manuscript.

**Data availability** No datasets were generated or analysed during the current study.

## Declarations

**Ethics approval** Not applicable

**Consent to participate** Not applicable

**Consent for publication** Not applicable

**Competing interests** The authors declare no competing interests.

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