A new species of Trichobius (Diptera: Streblidae) from Mexico and new record of Paratrichobius americanus

A new species of Trichobius Gervais, 1844 (Diptera: Streblidae) is described from specimens collected in Jalisco, Mexico, from host bat Choeronycteris mexicana Tschudi. We place the new species within the “dugesii” group, because it shares certain characteristics with Trichobius urodermae Wenzel, 1966 T. angulatus Wenzel, 1976 and T. tiptoni Wenzel, 1976. However, it is easy to differentiate from all known species due to the chaetotaxy of the thorax, in which the prescutal and lateral setae are very long, while the discal setae are abruptly smaller and denser. It also possesses the metasternal lobe, which is very broad and translucent. We found a male of Paratrichobius americanus Peterson & Ross, 1972 on the same host individual, which expands the distribution area of P. americanus into Mexico because the unique holotype was collected in Arizona.

Within the family Phyllostomidae, records of bat flies on the host Choeronycteris mexicana are very limited, despite the wide distribution of this bat, which is found from the southwestern United States, Mexico to El Salvador and Honduras. It is widespread in Mexico, except for the Yucatan Peninsula (Arroyo-Cabrales et al., 1987;Ortega & Arita, 2005). However, there are only two studies where three species of bat flies are reported to parasitize this host (Peterson & Ross, 1972;Ramírez-Martínez et al., 2016). Peterson and Ross (1972) reported a new species of streblid from a collection of Choeronycteris mexicana; two males of the genus Paratrichobius, which were described as Paratrichobius americanus. Together with these specimens, they also found seven specimens of Trichobius that were apparently also a new species; however, they did not report more information about it. We captured two individuals of Choeronycteris mexicana, from which we identified the species Paratrichobius americanus (Fig. 1) using the description by Peterson and Ross (1972). However, three specimens of Trichobius (Fig. 2) have a distinct chaetotaxy of the thorax and as well as the size of the metasternal lobe, both structures are very important in determining the species of this genus. Following the keys to this genus given by Wenzel et al. (1966), Wenzel (1976), or Guerrero (1995, we found that the characteristics of these specimens were visibly different from the species described in the keys. At the same time, these specimens did not resemble the descriptions of new species of Trichobius made by Peterson and Hůrka (1974). Here, we describe a new species of Trichobius from Mexico which belongs to the ''dugesii'' group, and report new records of P. americanus from that country.

Materials and methods
Bats were captured in an open cattle pasture in Ejido Ahuacapan, located 8.3 km south of Autlan de Navarro, Jalisco, Mexico (Fig. 3). The landscape of the study area is a valley mainly composed of farmland and grasslands, while on the slopes of the hills there are fragments of seasonally dry tropical forest and riparian vegetation. To capture the bats, we used four mist nets measuring 12 x 2.6 m; two were placed in the pasture and two more within a corridor of trees. The nets were opened for six hours beginning at sunset for four consecutive nights. The captured bats were identified to the species level at the capture site, using field guides and taxonomic keys, and then released at that site (Medellín et al., 2007;Mónica-Díaz et al., 2021;Reid, 1997). The bat flies were collected following the method used by Tlapaya et al. (2019).
The collected flies were photographed using a Zeiss Discovery V12 stereoscope coupled to a Zeiss AxioCam 305 ZenPro (ZEN 3.2 Blue edition software) at the Centro Universitario de la Costa Sur, Universidad de Guadalajara, Mexico.
Description. Head. Slightly wider than long. Eyes with 11 facets. Laterovertices and occipital lobes moderately sclerotized. Each of the laterovertices with five long, strong setae and one minute setae; occipital lobes with seven very strong setae and one short setae below posterior margin. Palpi rounded-oval, ventral surface with three rows of setae on the basal half, six setae on  the margins of each palp, one very long and strong, three shorter about half the size, and two very small (Fig. 4). Theca elongated, but not triangular, although the base is wider than the tip, pear-shaped. Thorax. Anterior margin slightly projecting along the middle and slightly emarginated at midline; median suture present on apical half, transverse suture slightly angulated. Prescutum with 24 macrosetae, and 40 very short median discal setae. Scutum with about 60 conspicuous microsetae; four macrosetae on each lateral margin of the scutum, short antescutellar setae, the same size as the discal setae (Fig. 5). Mesosternum with oblique lateral margins, anterior margin feebly emarginated. The metasternal lobe is large, translucent, strongly dorsally reflexed and is not united with the metepimeron (Fig. 6). Wings. R 1 almost straight, subparallel to the coast; R s slightly larger than the distance between the bifurcation and the cross-vein r-m (Fig. 7). Abdomen. Female: lateral lobe of tergum I?II with 16-20 setae (Fig. 8). Two minute setae on the seventh tergum. Epiproct with four apical macrosetae (Fig. 9A). Sternum VII with 7 macrosetae of which one is at least three times larger than the previous ones (Fig. 9B).

Remarks
The type material of this species consists of two female specimens preserved in 70% alcohol. A male specimen was also collected, but it presented lesions on its last segment of the abdomen and thorax, so it was not possible to carry out a diagnosis. Despite these damaged parts, the specimen adequately shows sufficiently distinctive characteristics of the thorax and the metasternal lobe to determine that it is a male of the same species. It is important to note the difference in the number of setae of the lateral lobe of the tergum I?II observed in the type material; the holotype presented 20 setae, and 16 setae were observed in the paratype.
Measurements: The measurements of the type series include the holotype $, the paratype $ and paratype # (Table 1)   The holotype and paratype were deposited in the Laboratorio de Ecología y Zoonosis of the Universidad de Guadalajara.
Etymology: The name for this new species of the bat fly alludes to the scientific name of the bat host (Choeronycteris mexicana).
The new species (T. mexicanus) belongs to the T. dugesii complex, as evidenced by the presence of metasternal lobe, which is not joined to the metapimeron, as well as the scutum and prescutum covered with setae that become abruptly shorter posteriorly, typical characteristics of some species of this complex. When consulting the keys by Wenzel et al. (1966), our specimen presented characters that resemble T. urodermae. However, T. urodemae has nine facets, while T. mexicanus has 11. Trichobius urodermae has prescutal setae three times as long as the discal setae, and antescutellar setae twice as long as the discal setae, whereas T. mexicanus has prescutal setae at least eight times longer than the discal setae, and the antescutellar setae are the same size as the discal and scutellar setae. Finally, we observed differences in the VII tergum and supranal plate. Trichoibus urodermae is characterized by a narrow transverse strip with longer setae on each side and a shorter middle and slightly posterior pair on tergum VII and four macrosetae and two shorter setae on each side of the epiproct. In T. mexicanus, the tergum VII has a single pair of tiny setae, and only four macrosetae on the epiproct.
According to Wenzel (1976), our specimens are similar to T. assimilis or T. angulatus, because these species present a metasternal lobe and a strongly angulated transverse mesotonal suture. These species also have prescutal setae longer than those posterior. However, the discal setae of T. mexicanus are noticeably denser and shorter than on the prescutum, while in T. assimilis the discal mesotonal setae are less dense than the prescutal setae. On the other hand, T. angulatus has longer antescutellar than discal setae, while in T. mexicanus, the discal and the antescutellar setae are the same size. Moreover, T. assimilis has a setae on each lateral margin of the epiproct, which is not present in T. mexicanus. Therefore, the females of T. mexicanus may be distinguished from those of other species of the dugesii group by the presence of a single pair of minute setae on the tergum VII and the size of the antescutellar and prescutal setae, which are very large relative to those of the rest of the species of the group. This latter character is only shared with T. tiptoni however, this species also has very long antescutellar seta, while in T. mexicanus they are shorter. Other species of the group can also be differentiated by the presence of two pairs of setae on the tergum VII.

Discussion
A first step to understand and be able to determine parasite-host specificity is to better assess the richness of streblids, because there are regions and species of bats for which there is still little or no information on the diversity of this family. Recent description of the new genera and two new species of streblids show the  importance to increase the efforts to know the diversity of this group (Graciolli et al., 2022). At the same time, there are bat species for which there is little information on the bat-flies bat relationship, as is the case of Choeronycteris mexicana. Peterson and Ross (1972) carried out the first study with C. mexicana, that reported a new species (Pararichobius americanus). The authors discussed the possibility of contamination, since most species of Paratrichobius are associated with the Stenodermatinae (Dick, 2013;Peterson & Ross, 1972), while C. mexicana belongs to the Glossophaginae. We captured two individuals of C. mexicana that, in addition to hosting Trichobius mexicanus (Fig. 10), were also parasitized with 1 and 7 males, respectively, of P. americanus, confirming the association of this parasite with C. mexicana as initially reported by Peterson and Ross (1972). On the other hand, Ramírez-Martínez et al. (2016), reported Megistopoda proxima in C. mexicana, however, this species of streblid is specific to Sturnira lilium (Dick, 2013). This shows the importance of expanding and continuing the inventories of bat flies and host, gathering more information in order to corroborate these observations. With this work, we report a new bat fly species association with Choeronycteris mexicana. Moreover, the distribution of P. americanus is expanded, which previously had only been reported in the state of Arizona, United States by Peterson and Ross (1972). Our finding represents the first record of this species in 50 years after its description and a new record for Mexico ( Fig. 10) Therefore, we highlight the importance of intensifying efforts to continue to compile faunal lists, focusing on little-studied hosts such as C. mexicana.
Acknowledgements Thanks to the Ecology of Zoonosis in west coast of Jalisco, Mexico project from Ramírez-Martínez M. M. and her Lab. This work is part of the results obtained from the postdoctoral project ''Especificidad en la relación parásitohospedero entre estréblidos y murciélagos de la region Costa Sur y Sierra de Amula en Jalisco, México'' which is supported by CONACYT through the postdoctoral fellowship awarded to the first author (442273) and with the support of the Doctoral Program in Biosystematics, Ecology, Natural and Agricultural Resource Management (BEMARENA). We want to thank Dr. Ramón Cuevas Guzmán for providing the facilities to take the photographs and Dr. Gustavo Graciolli for reviewing our manuscript, which was improved by his comments and suggestions. We also thank Nereyda Pablo Rodríguez for helping us to edit the images and two anonymous reviewers for their comments to improve our manuscript.
Author contribution LTR performed the taxonomic identification of streblids, took the photographs, and wrote the paper. MMRM and AGM planned and designed the study and conducted the fieldwork: collected the specimens (bat flies and bats), identified the bat species, and made final revisions to the manuscript. All authors read and approved the final manuscript Funding The present project was supported by CONACYT through the postdoctoral fellowship awarded to Tlapaya- Romero L. and García-Méndez A. and with funding from the Universidad de Guadalajara, through a Grant awarded to Ramírez-Martínez M. M.

Declarations
Conflict of interest The authors declare that they have no conflict of interest. The authors have no relevant financial or non-financial interests to disclose.
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