New geographical and host record of bat ectoparasite Steatonyssus ( Steatonyssus ) afer Radovsky and Yunker, 1963 (Mesostigmata: Gamasina: Macronyssidae)

Steatonyssus afer is recorded for the first time from Namibia and for the first time from Cistugo seabrae (Chiroptera: Cistugidae). Our finding is the southernmost locality for S. afer , expanding the geographical distribution range of this ectoparasite. We give diagnostic illustrations and measurements of the species.


Materials and methods
We conducted research on Namib Desert bats and their ectoparasites in the Kunene Region of northwestern Namibia (Fig. 1). This region is comprised of pastoralist communal conservancies and tourism concessions bordering Skeleton Coast Park, and receives~30 to 100 mm of rainfall, on average, between January and April each year (Jacobson and Jacobson, 2013).
From 6 December 2016 to 4 April 2017, we intensively examined captured bats for ectoparasites. We captured bats by deploying mist nets (2 m high by 4 to 12 m in length) above bodies of water for 1 to 3 hr after sunset for a total of 120.37 hr over 37 nights. We removed bats from mist nets within 1 to 5 min of capture and placed them in cloth bags until they could be processed 0 to 15 min later. Bats were morphologically identified using taxonomic descriptions by Monadjem et al. (2010) and we recorded the following data for each bat: sex, age (juvenile or adult), forearm length (mm), body mass (g), and reproductive status (nonreproductive, reproductive, pregnant, or lactating). The body (front, back, tail, wings, ears, uropatagium, etc.) of all bats were thoroughly and systematically surveyed in hand and examined for ectoparasites using an LED headlamp.
All ectoparasites were removed with forceps, pooled into one sample for each individual bat, and preserved in 95% ethanol before the bats were released. For each ectoparasite sample, we transferred the mites into a new vial containing 70% ethanol and sent all mites to the Institute Xbio of Tyumen State University (Russia) for species identification. After clearing, the mites were mounted on permanent slides with FaureBerlese's mounting medium (Whitaker, 1988). Morphological identification of mites was done by the first author (MO), according to the keys by Till and Evans (1964). The morphological terminology generally follows Evans and Till (1979). Dorsal and ventral setae were labelled according to the systems of Lindquist and Evans (1965). Photographs were taken with a digital camera AxioCam ICc5 (Zeiss, Germany) via a compound microscope AxioImager A2 (Zeiss, Germany) with a phasecontrast and DIC objectives. All measurements are given in micrometers (μm).
The specimens mounted on five slides were deposited at the collection of the Tyumen State University's Museum of Zoology, Tyumen Province, Russia.

Results and discussion
Five specimens of macronyssid mites (Mesotigmata: Gamasina: Macronyssidae) were obtained from adult females of the Angolan winggland bat C. seabrae, in two localities of Namibia: Okongwe ( S E) (one bat) and the junction of the Hoanib and Mudorib Rivers ( S E) (onr bat). Mites (five females) were morphologically identified as S. afer. Measurement information from the present study and previous ones is provided in Table 1.

Family Macronyssidae
Genus Steatonyssus Kolenati, 1858 Type species: Steatonyssus periblepharus Kolenati, 1858, by designation of Till and Evans, 1964 Steatonyssus (Steatonyssus) afer Radovsky and Yunker, 1963 Figures 2-3 Differential diagnosis (female) -Steatonyssus afer is morphologically closest to S. roeri. The anterior margin of the sternal plate can hardly be detected in S. afer (vs. well defined in S. roeri). In S. afer, the peritreme starts ventral and bends over to the dorsal surface for most of its length, while the peritrematal plate is interrupted with a leaflike portion lying over coxae I and II (vs. not interrupted plate in S. roeri). The setae on the opisthonotal and podonotal shields are considerably longer and thicker in S. afer than in S. roeri (5471 vs. 4047, respectively).
Remarks -We note that there is a fairly large variation in size among the mites recorded so far (in Namibia in this study and in different regions in the literature; Table 1). Since we were only able to examine five specimens from Namibia (from five bats in two distant localities) and could not standardize our measurements by performing them in parallel on the types, we cannot conclude about possible crypticism within the species S. afer. However, we suggest that  Table 1 Comparison of metric data of body parts between Steatonyssus afer adult female from Namibia and those described in Angola. All measurements are given in micrometers (μm).

Steatonyssus afer Steatonyssus afer Steatonyssus roeri
Angola Namibia Namibia Body part (Radovsky, Yunker, 1963;Till, Evans, 1964) (this paper) (Coffee, 1973)  it would be useful to explore the genetic structure of this taxon by morphological comparisons on a larger and more representative sample and, if possible, by adding a molecular analysis to the morphological analysis. The individuals present the first record of S. afer for Namibia and the southernmost locality for the species to date. Also, C. seabrae is recorded as another host of the parasite.
Given the poor knowledge of genus Steatonyssus in Africa, there is a need for further research on Steatonyssus species throughout Africa to establish complete host lists and geographical ranges of these ectoparasites.
We are grateful to Dr. B. Halliday for his valuable comments and to the anonymous reviewers, whose advices made our manuscript substantially better.