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Distinguishing the Urothripine genera 1. Compound eyes each with at least 30 facets (Figs 40–41), all equal in size; antennal segment III slender, usually 3–4 times as long as wide and not narrowed sharply to base; mid and hind tarsi 2-segmented; fore tarsal hamus directed ventrally; metathoracic epimera each with a prominent lateral seta....................................................... 2 -. Compound eyes never with more than 15 facets (Figs 27–28), some dorsal facets much larger than others; antennal segment III almost globose, scarcely 2 times as long as wide and sharply narrowed to basal stem (sometimes fused to segment IV or to IV+ V); mid and hind tarsi 1-segmented; fore tarsal hamus, when present, directed laterally; metathoracic epimera with or without such a seta.................................................................................... 3 2. Head projecting over bases of first antennal segment (Fig 41); eyes almost holoptic but with no facets ventrally; head with genae narrowing to base; prosternal basantra present and transverse.................................... Octurothrips -. Head projecting strongly in front of eyes with antennae arising at apex (Fig. 40); compound eyes globose on dorsal and ventral surfaces; head sharply narrowed to base; prosternal basantra reduced to weak sclerites placed anterolaterally.... Habrothrips 3. Prosternal basantra transverse across anterior margins of ferna......................................... Trachythrips -. Prosternal basantra absent or reduced to small anterolateral sclerites............................................. 4 4. Anterior margin of head with prominent setae, rarely reduced to a single small pair (Figs 26–32)...................... 5 -. Anterior margin of head with no prominent setae (Figs 33–38)................................................. 6 5. Antennal segment III narrowed at apex and distinct from narrowed base of IV (Fig. 9); maxillary stylets close together medially in head..................................................................................... Bradythrips -. Antennal segment III broad at apex and close to broad base of IV, segments III– V weakly to closely fused; maxillary stylets about 0.3 of head width apart................................................................. Stephanothrips 6. Fore tarsus with hamus.......................................................................... Urothrips -. Fore tarsal hamus absent................................................................... Amphibolothrips

Octurothrips Priesner Octurothrips Priesner, 1931: 93. Type species Octurothrips pulcher Priesner. Known only from Australia, the single species in this genus has been found widely in the inland arid zone of the eastern part of this continent (Figs 41–42). Although all of the available specimens are apterae, the species shares many character states with Habrothrips curiosus, including the abdominal tergites with a groove down the midline. However, the head is remarkable with greatly enlarged, almost holoptic. compound eyes, with the genae extending forward laterally around the eyes, and the prosternal basantra large and transverse.

Trachythrips Hood Trachythrips Hood, 1930: 317. Type species Trachythrips watsoni Hood. Alone amongst the urothripine genera, the members of this genus have the pronotal basantra fully transverse across the anterior margins of the ferna, although the posterior margin of the basantra is not always fully sclerotised in some of the specimens examined. This character state of the basantra, paralleling the geographical distribution of the genus, suggests a single New World radiation with the 11 members of the genus restricted to the American continent and Caribbean islands, between California, Texas, Florida and southern Brazil. Structurally similar to each other, the species of this genus apparently are all wingless, with some differing from others in little more than colour patterns.

Stephanothrips Trybom Stephanothrips Trybom, 1912: 42. Type species Stephanothrips buffai Trybom. Baenothrips Crawford, 1948: 39. Type species Baenothrips guatemalensis Crawford, syn.n. Verrucothrips Stannard, 1952: 128. Type species Amphibolothrips (Verrucothrips) caenosa Stannard. Ramachandraiella Ananthakrishnan, 1964: 228. Type species Ramachandraiella minuta Ananthakrishnan. Transithrips Bournier, 1963: 81. Type species Transithrips asper Bournier. Bournieria Ananthakrishnan, 1966: 2. Type species Bournieria indica Ananthakrishnan. Four of the generic synonyms indicated above were discussed by Mound (1972: 92), but the validity of Baenothrips has not been questioned since Stannard (1952). The sole distinction between Baenothrips and Stephanothrips has been in the degree of separation between antennal segments III–V, being separate in the first genus but largely fused in the second. Baenothrips guatemalensis, the type species of that genus, is interpreted as having segments III–V distinct from each other (Fig. 5), although the separation between them is by no means clear. Among the various species placed in Baenothrips only asper and cuneatus have these segments clearly separate (Fig. 8). In the only known specimen of guatemalensis segments VII and VIII are fused with scarcely any trace of suture, and this is also true of chiliensis (Fig. 7). Very similar to these in structure and sculpture, the Australian species, moundi, has segment VIII clearly distinct (Fig. 6). A further problem is that in another Australian species, B. caenosus, antennal segments VII and VIII can be either fused or separate (Mound 1972). There is also a lack of clarity in distinctions between some described species. For example, Bhatti (2002) published a detailed morphological study of a paratype of asper, recognizing that specimens identified as asper from India do not represent that African species. The original illustration of asper by Bournier, as well as the illustrations of a paratype by Bhatti, indicate that, in this species from Angola, antennal segments III–V are clearly distinct from each other, much as in cuneatus (Fig. 8). In contrast, the antennae of Indian specimens labelled by Ananthakrishnan as asper (Ooty, vii.1970) have segments III–V broadly joined. Our interpretation is that antennal segment fusion has been subject to several reversals among the various species, and that this character state cannot be employed to distinguish natural groups. As a result, the genus Baenothrips is here considered a synonym of Stephanothrips, and that genus will now include 47 species. These comprise 26 species from the Asian tropics, nine from Australia, three from Africa, and four from southern USA, plus four from South America where they are possibly introduced (see above Geographic considerations). In addition, because the only known males of occidentalis were taken in Thailand (Okajima & Urushihara 1995b), it is probable that this pantropical species is also Asian in origin. Since several of the nine species from Australia are known only from the northern subtropical parts of this continent, it is clear that the distribution of species in this genus is primarily in association with the southeast Asian tropics. The new synonymy of Baenothrips with Stephanothrips results in the 15 new combinations listed in Table 1.

Mound, Laurence A., Lima, Élison Fabrício B., O'Donnell, Cheryle A. (2023): What is a genus-interpreting structural diversity among species of urothripine Phlaeothripinae (Thysanoptera). Zootaxa 5319 (1): 91-102, DOI: 10.11646/zootaxa.5319.1.6, URL: http://dx.doi.org/10.11646/zootaxa.5319.1.6

Urothrips Bagnall Urothrips Bagnall, 1909: 126. Type species Urothrips paradoxus Bagnall. Coxothrips Bournier, 1963: 75. Type species Coxothrips reticulatus Bournier. Synonymised by Ulitzka & Mound, 2014. Ananthakrishnaniella Stannard, 1970: 118. Type species Ananthakrishnaniella tarai Stannard. Synonymised by Bhatti, 1998: 178. Biconothrips Stannard, 1970: 121. Type species Biconothrips reedi Stannard. Synonymised by Ulitzka & Mound, 2014. Within the key to genera of urothripines presented by Mound (1972), one group of four genera was distinguished by the following three character-states: absence of elongate setae on anterior margin of head; presence of prominent external fore tarsal hamus; reduction of prosternal basantra (=praepectus) to a pair of small triangles placed laterally. However, there is considerable overlap in character states amongst the nine species involved under these four generic names, and Ulitzka and Mound (2014) decided to include all nine species within a single genus, Urothrips. The alternative to accepting a single genus to encompass the range of variation amongst these species would be to recognise more than four monotypic genera, each of which would be supported by a single autapomorphy with no obvious systematic significance. The problem of distinguishing genera based on characters that seem to vary progressively in fusion or size increases when all 12 of the species now listed in Urothrips are considered. In one of these species, U. lancangensis, the fore tarsal hamus is very small, and in U. calvus it appears to be quite undeveloped. Similarly, the only available specimen of U. bagnalli Trybom is uncleared but seems to have transverse basantra. At species level within the genus there appear to be further problems, in that populations of paradoxus in Africa differ in colour details, as is known amongst populations of reedi in Australia (Mound 1972).

Bradythrips Hood & Williams Bradythrips Hood & Williams, in Hood, 1925: 68. Type species Bradythrips hesperus Hood & Williams. The type species was based on a single wingless female collected in Guyana, on the north coast of South America. However, at the U.S. National Museum in Washington and in the collections of Universidade Federal do Piauí, Floriano, in Brazil, we have studied in addition to this holotype the following wingless females of B. hesperus: one from Panama, seven from Guyana, and more than 10 from Brazil along the Amazon River basin (States of Amazonas, Pará and Amapá). In contrast, the other five species that are now known in this genus are all from southeast Asia, including Malaysia, southern China, Philippines and Borneo, and specimens of hesperus have also been recorded from India, Borneo and the Solomon Islands (Okajima 1987). These records indicate that Bradythrips is likely to be a genus of the Asian tropics but with one species that has been inadvertently transported to South America, probably by sailing ships. A key to five of the six species of Bradythrips is available (Okajima & Urushihara 1995a), and of the two species with the pronotum and fore legs yellow, zhangi differs from hesperus in having the head more uniformly brown and the abdominal tergites with narrow longitudinal sculpture medially. All six species have antennal segments III–V clearly distinct from each other, in contrast to the condition in Stephanothrips species. The members of Bradythrips differ from those previously placed in Baenothrips in having the maxillary stylets close together medially in the head, and only a single pair of prominent setae on the anterior margin of the head (Fig. 26). Although B. hesperus has the metathoracic epimera bearing a small stout seta laterally, it appears that the other members of this genus lack this structure.