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. 2021 Oct 28;12(11):974.
doi: 10.3390/insects12110974.

Landmark Data to Distinguish and Identify Morphologically Close Tabanus spp. (Diptera: Tabanidae)

Tanasak Changbunjong  1   2 , Nutnicha Prakaikowit  1 , Photchanun Maneephan  1 , Tipparat Kaewwiset  1 , Thekhawet Weluwanarak  2 , Tanawat Chaiphongpachara  3 , Jean-Pierre Dujardin  4
Affiliations

Landmark Data to Distinguish and Identify Morphologically Close Tabanus spp. (Diptera: Tabanidae)

Tanasak Changbunjong et al. Insects. .

Abstract

Tabanus spp., also known as horse flies (Diptera: Tabanidae), are important vectors of several animal pathogens. Adult females of Tabanus megalops and Tabanus striatus, which are members of the T. striatus complex, are morphologically similar and hence difficult to distinguish using morphological characteristics. In addition, molecular identification by DNA barcoding is also unable to distinguish these species. These two species can occur sympatrically with Tabanus rubidus, which is morphologically similar to T. megalops and T. striatus. Wing geometric morphometrics has been widely used in various insects to distinguish morphologically similar species. This study explored the effectiveness of landmark-based geometrics at distinguishing and identifying T. megalops, T. rubidus, and T. striatus in Thailand. Specimens were collected from different geographical regions of Thailand, and only unambiguously identified specimens were used for geometric morphometric analyses. Left wings of females of T. megalops (n = 160), T. rubidus (n = 165), and T. striatus (n = 85) were photographed, and 22 wing landmarks were used for the analysis. Wing shape was able to distinguish among species with high accuracy scores, ranging from 94.38% to 99.39%. We showed that morphologically very close species of Tabanus can be reliably distinguished by the geometry of their wing venation, and we showed how our experimental material could be used as a reference to tentatively identify new field collected specimens.

Keywords: Tabanus megalops; Tabanus rubidus; Tabanus striatus; geometric morphometrics; horse flies; vector.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Morphological characteristics of abdominal dorsum used to distinguish species of Tabanus megalops (A), T. rubidus (B), and T. striatus (C). Tabanus megalops and T. striatus are distinguished by the midline of the 2nd tergite cross by a stripe of pale tomentum and hairs in T. megalops (arrow).
Figure 2
Figure 2
Morphological characteristics of basal callus used to distinguish species of Tabanus megalops (A), T. rubidus (B), and T. striatus (C). Tabanus rubidus is distinguished from T. megalops and T. striatus by the basal callus, which is more triangular than rectangular (arrow).
Figure 3
Figure 3
Map of Tabanus collection sites in Thailand: Phitsanulok (1), Nakhon Pathom (2), Chainat (3), Prachuap Khiri Khan (4), Chumphon (5), Chiang Mai (6), Uthai Thani (7), Singburi (8), Nakhon Ratchasima (9, 10), and Sa Kaeo (11).
Figure 4
Figure 4
The twenty two landmarks digitized on the wing of Tabanus spp. for landmark-based geometric morphometric analysis.
Figure 5
Figure 5
Quantile boxes of centroid size variations of Tabanus megalops (red, leftmost box), T. rubidus (green, central box), and T. striatus (blue, rightmost box). The horizontal line crossing each box is the median separating the 25th and 75th quartiles.
Figure 6
Figure 6
Mean anatomical landmark positions of Tabanus megalops (red), T. rubidus (green), and T. striatus (blue) after Procrustes superposition.
Figure 7
Figure 7
Factor map of the discriminant factors (DF) showing shape divergence of Tabanus megalops (red), T. rubidus (green), and T. striatus (blue). Together, the two DF represent 100% of the total discriminant space: 85% for DF1 (horizontal axis) and 15% for DF2 (vertical axis).
Figure 8
Figure 8
Linear regression prediction (orange dots line) of the first shape-based discriminant factor (DF) (vertical axis) according to the centroid size variation (horizontal axis).
Figure 9
Figure 9
Hierarchical clustering tree based on shape similarities of reference data and unknown specimens. Unknown A: specimens from Chainat Province; Unknown B: specimens from Uthai Thani Province; and Unknown C: specimens from Nakhon Ratchasima Province. In this total sample classification analysis, all the specimens, including the unknown ones, helped with computing the discriminant model. The distances used for the tree construction were the Mahalanobis distances. Numbers at the nodes indicate the percentages of bootstrap values based on 1000 replicates.
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References

    1. Morita S.I., Bayless K.M., Yeates D.K., Wiegmann B.M. Molecular phylogeny of the horse flies: A framework for renewing tabanid taxonomy. Syst. Entomol. 2016;41:56–72. doi: 10.1111/syen.12145. - DOI
    1. Stern A.W. African horse sickness. Compend. Contin. Educ. Vet. 2011;33:E1–E5. - PubMed
    1. Baldacchino F., Desquesnes M., Mihok S., Foil L.D., Duvallet G., Jittapalapong S. Tabanids: Neglected subjects of research, but important vectors of disease agents. Infect. Genet. Evol. 2014;28:596–615. doi: 10.1016/j.meegid.2014.03.029. - DOI - PubMed
    1. Mullen B.A. Horse Flies and Deer Flies (Tabanidae) In: Mullen G.R., Durden L.A., editors. Medical and Veterinary Entomology. 3rd ed. Academic Press; London, UK: 2019. pp. 327–343.
    1. Burton J.J.S. Tabanini of Thailand above the Isthmus of Kra (Diptera: Tabanidae) Entomological Reprint Specialists; Los Angeles, CA, USA: 1978.

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