Haplothrips Amyot & Serville

Haplothrips Amyot & Serville

Haplothrips Amyot & Serville, 1843: 640. Type species Phloeothrips albipennis Burmeister [= Thrips aculeatus Fabricius], by monotypy.

Jironiella Retana-Salazar & Soto-Rodriguez, 2007: 632. Type species Jironiella saidi Retana-Salazar & Soto-Rodriguez, by monotypy. Syn.n.

The genus Jironiella was erected for a single species collected from Cyperaceae in Costa Rica, and was distinguished from Haplothrips on the grounds that the maxillary bridge between the maxillary stylets in the head is “absent”. Goldarazena et al. (2008) disputed this statement, claiming that fragments of the maxillary bridge could be seen in a paratype of saidi, and they regarded Jironiella as a synonym of Haplothrips. Unfortunately, these authors also erroneously synonymized saidi with Haplothrips graminis Hood, a common species on grasses in Central America. In contrast, Bhatti et al. (2020) rejected the generic synonymy and re-validated the genus Jironiella, as discussed below. We have now re-examined the saidi paratype and confirm that the maxillary bridge is “not visible”, and that saidi is a valid species distinguishable from graminis.

In rejecting the synonymy of Jironiella with Haplothrips Bhatti et al. (2020) provided no other discriminating character state to distinguish these genera apart from the lack of a maxillary bridge. No comment was made on the phylogenetic relationship between them, despite the many shared character states and the fact that many Haplothrips species also live on Poaceae and Cyperaceae. Although the paper by Bhatti et al. (2020) was published in an Indian journal, no mention was made of a genus from India, Aphlothrips Tyagi & Kumar (2006), that was also described for a single species taken from grass. That genus was also distinguished from Haplothrips only by the absence of a maxillary bridge. Thus, even if the “absence” of a maxillary bridge is considered phylogenetically significant, the genus Jironiella might need to be considered a synonym of Aphlothrips. Given that the species involved share most of their character states with the species of Haplothrips, there are two ways of interpreting this situation: either these two species from disparate parts of the world represent an ancient lineage in which the maxillary bridge that is typical of Haplothripini had not yet evolved, or the absence of the maxillary bridge in the two species is a reversal – that is, a “loss apomorphy”. There being no evidence to support the first possibility, the second is here considered to be the most sensible as it is in accordance with the well-established philosophical principle of parsimony known as Occam’s Razor.

Curiously, Bhatti et al. (2020) stated in the “ABSTRACT” to their paper “ Jironiella is related to Bamboosiella ” another genus associated with Poaceae. But the authors give no information in support of this statement in the main text of the paper. They ignored that the species of Bamboosiella lack prosternal basantral sclerites, the antennae have two sense cones on the third segment and three on the fourth, and the maxillary stylets are scarcely retracted into the head capsule anterior to the post-occipital ridge. Currently, because of these character states, the genus Bamboosiella is not considered to be a member of the tribe Haplothripini (Okajima 2006; Mound & Minaei 2007). We therefore conclude that the apparent absence of a maxillary bridge in the Costa Rican species Haplothrips saidi is yet another “loss apomorphy”, a reversal that has arisen more than once among Haplothrips species, and is thus of limited significance in indicating systematic relationships within this species-rich genus.