Brevipalpus, Donnadieu, 1875

SaccaggiK, Davina L. & UeckermannK, Edward A., 2024, The problem of taxonomic uncertainty in biosecurity: South African mite interceptions as an example, Acarologia 64 (2), pp. 363-369 : 364-366

The unknown Brevipalpus

In 2007 a Brevipalpus species was intercepted for the first time from Italy ( Saccaggi et al. 2021 ; Tshikhudo et al. 2021). This species appeared similar to B. lewisi McGregor, 1949 , at the time a listed quarantine pest (see metadata in Saccaggi et al. (2021)). The same unknown species was repeatedly intercepted on European kiwifruit, first from Italy, then from Greece in 2010,

and finally from France in 2015 ( Table 1). Interestingly, this Brevipalpus species was never intercepted on kiwifruit originating from New Zealand, the main source of kiwifruit to South Africa. However, despite extensive consultation between the authors and international experts,

it could not be positively identified. At this point we concluded that it was most likely a new species, and were encouraged to publish a new species description based on the intercepted specimens. However, biological, taxonomic and economical concerns and challenges had a significant impact on further decision-making.

1. We had limited biological information available to us. We had only intercepted adults on fresh fruit. No interceptions of immature specimens on fresh fruit, nor any interceptions on dormant plant material were recorded. Therefore, we felt we could not definitively the identify kiwi as a host for the whole life cycle. Possibly this Brevipalpus was moving onto kiwi opportunistically when another host was not available, in which case we would need to identify the primary host. We preferred to err on the side of caution until further biological evidence could be gathered. 2. The genus Brevipalpus is a large and taxonomically challenging genus ( Beard et al. 2015). Many of the almost 300 Brevipalpus species are poorly described or unrecognisable, and many of the older type specimens are lost ( Mesa et al. 2009 ; Castro et al. 2023). We had no desire to add to this taxonomic conundrum without conclusive evidence of species status. 3. We had limited access to different Brevipalpus specimens for comparison. The South African National Collection (SANC) of Acari holds around 300 Brevipalpus specimens, mostly species of common agricultural pests, which we had already eliminated as a possible match. Access to larger Acari collections, where comparison to a wider diversity may have been possible, was limited. Colleagues were able to send us some images of Brevipalpus specimens or additional taxonomic information (R. Ochoa, personal communication), but without dedicated study of the slides we were unable to make robust comparisons. 4. The sensitivity of international trade meant we had to be cautious regarding sharing of information internationally, as misinterpretation or premature publication could potentially lead to additional quarantine measures or trade disputes.

now known to be B. garmani (a-c), from B. lewisi (d-f). Images show: spermathecal vesicle (a,d), with larger and brighter buddle in unknown species (a); reticulation on the venter between coxae I-II (b,e), extending further forward in the unknown species (b); and rostral shield showing the different shape of the lobes, indicated by arrows (c,f). Images were captured on a Leica DM2500 compound microscope with a 100X objective using Differential Interference Contrast (DIC), connected to a Leica digital camera and Leica application suit v3.1.0 software.

As we continued intercepting the same species, we could observe more specimens and identifications became more certain. In total, 54 interceptions of this Brevipalpus species were recorded by South Africa, with each instance accompanied by slide-mounted and archived reference specimens. We developed a short protocol for differentiation of this mite from

Brevipalpus lewisi , to which it was very similar ( Figure 2 ). This meticulous record-keeping helped immensely in keeping track of this mystery that spanned 16 years.

In 2021, an Italian research group independently initiated a survey on kiwis in Italy ( De

Giosa et al. 2024). As part of this survey, they reached out to us to enquire about our findings on kiwi. Their survey failed to find mites that matched our mystery Brevipalpus species, and the trail seemed to run cold again.

However, a researcher involved in the Italian survey moved to the USA and started working with a Brevipalpus taxonomist there. This opened a three-way collaboration between acarologists from South Africa, Italy and the USA working on biosecurity, distribution and taxonomy of Brevipalpus mites. From South Africa, we provided 13 slide-mounted intercepted

Brevipalpus specimens (10 from Italy and three from France). From Italy, an archived slide with nymphs and adults matching our mystery species was found. And from the USA, types specimens of Brevipalpus species housed in the US National Museum of Natural History

(USNM, the Smithsonian) were examined and compared. Thus, in 2023, 16 years after its first interception, the specimens intercepted in South Africa could be compared with European and

American specimens and eventually identified Brevipalpus as garmani Baker, 1949 .

We were then able to retrospectively review the South African interception records and give the unknown Brevipalpus species its rightful name. These new identifications, along with other Brevipalpus interceptions on kiwifruit, are presented in Table 1.

tries. Data from 2007-2019 is from Saccaggi et al. (2021), with the Brevipalpus identifications updated. Records after 2019 are new data presented in this publication.

Figures

Figure 2 Images of slide-mounted specimens, showing features which could clearly distinguish the intercepted unknownBrevipalpus species,