Ocnothrips cochinchinensis (Karny) Mound, 2020

Mound, Laurence, 2020, Taxonomic confusion among gall-thrips and host-plants, with three new combinations from the genus Austrothrips (Thysanoptera, Phlaeothripidae), Zootaxa 4755 (3), pp. 587-592 : 588-590

Ocnothrips cochinchinensis (Karny) comb.n.

( Figs 1–6 )

Austrothrips cochinchinensis Karny, 1922: 113 .

Ocnothrips indicus Ananthakrishnan, 1969: 188 . Syn.n.

The genus Ocnothrips was erected for a single new species, indicus , of which the author gave details of the holotype male together with the statement “ Paratype: same locality together with holotype ”. It is not clear from this if there was a single paratype or several paratypes. These specimens were found in a leaf gall on a species of Piper in Kerala, southwestern India. Also in this gall were adults of two species now placed in the genus Liothrips that are known to be gall-inducers on leaves of Piper species. Thus the relationship of indicus to this gall also remains unclear. Curiously, in his extensive studies on gall thrips, Ananthakrishnan (1978) did not mention Ocnothrips , although Ananthakrishnan & Sen (1980) indicated in a footnote on page 38 that “ Ocuothrips ” was “similar to Austrothrips ” and this is here assumed to be a spelling error. The type specimens of O. indicus have not been studied, but two females are listed below that were identified as this species by the Zoological Survey of India (pers. comm. R. Varatharajan ii.2020). These specimens, together with Ananthakrishnan’s original illustrations and the statement quoted above, lead to the conclusion that indicus and cochinchinensis are not only congeneric but represent the same species. The pelta of indicus as illustrated by Ananthakrishnan is similar in shape and sculpture to that of cochinchinensis , and the antennae are also similar in form. In contrast, the description of indicus makes no mention of reticulate sculpture on the head and metanotum.

The plant associations of this thrips require further study. Certainly, in western India it induces pouch galls on the Combretaceae species, Getonia floribunda . But indicus was described from adults taken on a species of Piper , and according to Thang Johnson (pers comm. 2020) this thrips has also been taken from leaf galls on Piper at the University of Manipur. Ananthakrishnan (1969) indicated the leaf-roll galls in which indicus adults were taken were induced by one or two thrips species that are now placed in the genus Liothrips . There is thus no clear evidence of cochinchinensis actually inducing galls on Piper species; its presence in such galls could well be another example of the typical thigmotactic habit of many thrips species. However, Thang Johnson has also indicated that this thrips species has been found in galls on Quercus , and that larval thrips were also found in these galls. This association requires further field studies, in order to test the assumed monophagy of cochinchinensis . The following description is to supplement the notes in Karny (1922).

Male and female macropterae. Body brown, tarsi and apices of tibiae yellow, antennal segments III–VI brownish-yellow, VII–VIII light brown; fore wings weakly shaded, darker near base, clavus dark; major setae pale. Head with irregular reticulation ( Fig. 1 ), particularly on posterior half, genae overlap eyes laterally; postocular setae capitate, longer than eye length; maxillary stylets retracted to eyes, close together medially with small maxillary bridge. Antennae 8-segmented ( Fig. 2 ), VIII slender, IV–VI almost moniliform; III–V each with 2 sense cones of which the outer is usually larger than the inner, but segment IV sometimes bears 3 sense cones (including 2 antennae of the syntypes). Pronotum with notopleural sutures complete ( Fig. 4 ); with 5 pairs of long capitate major setae, epimeral setae sometimes duplicated, am setae longer than aa setae. Fore tarsus with no tooth in either sex. Mesonotal lateral setae capitate ( Fig. 5 ); metanotum reticulate, median setae variable from bluntly pointed to broadly capitate. Prosternal basantra absent, ferna wide apart, mesopresternum transverse but slender; metathoracic sterno-pleural sutures well developed. Pelta reticulate with prominent lateral wings; tergites II–VII each with 2 pairs of sigmoid wing-retaining setae, posterior pair strongest on each tergite; tergite II with no discal setae laterally; tergite IX setae S1 and S2 capitate and about two-thirds as long as tube; Sternites each with one pair of long marginal setae; discal setae small in irregular transverse row. Male tergite IX setae S2 capitate and shorter than S1, sternite VIII with no pore plate.

Specimens studied. Cotypes of cochinchinensis , Thailand, Southern Siam, Ban Klang Tahu , female in gall of a Combretaceae ( Quisqualis ?), 1.x.1920; Vietnam, near Saigon, male from leaf gall, 19.ix.1920, in Senckenberg Museum, Frankfurt.

Non-types. India, Nagaland, Kikruma, 2 females from Quercus dealbata leaf gall, 7.vi.2001 ( Varatharajan ); Kerala, Malappuram , Calicut University , 22 females, 14 males, with larvae from galls on Getonia floribunda , 7.viii.2019 ( Nasser ), in ANIC, Canberra .

Figures

FIGURES 1–6. Ocnothrips cochinchinensis. (1) head; (2) antenna; (3) pelta and tergites I–II; (4) pronotum; (5) mes and metanotum; (6) type slides.