Aesthesiothrips Ananthakrishnan

Okajima, Shûji & Masumoto, Masami, 2023, Six genera of the subtribe Macrothripina from Southeast Asia to Taiwan (Thysanoptera, Phlaeothripidae, Idolothripinae), Zootaxa 5291 (1), pp. 1-74 : 7

Aesthesiothrips Ananthakrishnan

Aesthesiothrips Ananthakrishnan, 1961: 253 . Type-species: Aesthesiothrips jatrophae Ananthakrishnan , by monotypy.

The generic definition of Aesthesiothrips was provided in detail by Palmer and Mound (1978: 163). In the definition, the following character states might be important: head elongate with dorsum convex; postocular setae short; postocellar setae elongate; eyes slightly prolonged ventrally; antennal segment III shorter than segment IV; sense-cones on III and IV longer than the segment; maxillary stylets deeply retracted to eyes and close together in the middle of head; fore tibia with an apical inner tubercle; pelta irregularly triangular, recessed into the anterior margin of tergite II. At that time, however, only one species, A. jatrophae , was known, but with the addition of two new species described below, A. breviconus sp. n. and A. elongatus sp. n., the generic definition needed to be re-examined. The short antennal segment III and the long sense-cones might be recognised as important features of the genus, but the same character states are also found in certain species of Ethirothrips , such as E. indicus and E. rubeus . Moreover, A. breviconus has antennal segment III short, but the sense-cones rather short, about half of the segment length. The long postocellar setae are also found in some Ethirothrips species , such as E. puiensis sp. n., E. obscurus and E. ommatus sp. n., and A. breviconus sp. n. has the postocular setae elongate ( Fig. 1 ) and the compound eyes not prolonged ventrally ( Fig. 2 ). Finally, the two new species do not have the fore tibial apical tubercle ( Figs 6 and 11 ). As a result, the features that characterise the genus Aesthesiothrips can be aggregated into the elongate and dorsally elevated head, the extremely long and medially closed maxillary stylets and characteristic shape of pelta which is irregularly triangular with recurved lateral wings and recessed into the anterior margin of tergite II. However, this still leaves some ambiguity: the head of Ethirothrips tenuis sp. n. described below is not strongly elevated dorsally, but has the maxillary stylets long and close medially ( Fig. 156 ) as well as the pelta very similar to that of Aesthesiothrips species ( Fig. 159 ). This species seems to be somewhat intermediate between these two genera, and may suggest that Aesthesiothrips is closely related to Ethirothrips , judging from the shared character states. The gap between these two genera may possibly be closed if more species are discovered in the future.

Diagnosis. Large sized species of Macrothripina . Head elongate, much longer than 2.0 times as long as broad, strongly elevated dorsally along midline, basal collar protruded posteriorly at middle; cheeks almost straight, or very weakly rounded, without distinct setae. Postocular setae variable in length; postocellar setae elongate, situated just behind posterior margins of posterior ocelli or between them. Ventral surface of eyes prolonged posteriorly or not. Antennae 8-segmented, segment III shorter than IV; segment III with two, segment IV with four sense-cones; sense-cones usually longer than segment, but often shorter. Mouth cone short and rounded; maxillary stylets very long, touching together medially, reaching eyes. Prothoracic notopleural sutures complete. Fore femora unarmed in both sexes; fore tibiae often with an inner apical tubercle; fore tarsal tooth present in both sexes. Metanotal median setae short. Pelta irregularly triangular with recurved lateral wings and recessed into the anterior margin of tergite II. Tube slender.

Key to Aesthesiothrips species

1. Fore tibia with a small inner apical tubercle ( Fig. 18 ) in both sexes; head shorter than 2.3 times as long as broad ( Fig. 15 ); basal collar of head slightly protruded posteriorly at middle................................................. jatrophae

- Fore tibia unarmed; head about 2.5 times as long as broad, or a little longer; basal collar of head strongly protruded posteriorly at middle............................................................................................ 2

2. Postocular setae elongate, longer than postocellars ( Fig. 1 ); postocellar setae situated between posterior ocelli; sense-cones short, about 1/2 length in segment III; eyes not prolonged ventrally ( Fig. 2 ); metanotum sculptured with fine reticulation around median pair of setae ( Fig. 5 ); fore tibiae dark brown ( Fig. 6 ), almost as dark as femora; tube almost as long as head in female; fore wings pale.......................................................................... breviconus sp. n.

- Postocular setae short, shorter than 1/2 length of postocellars ( Fig. 8 ); postocellar setae situated on a level of posterior margins of posterior ocelli; sense-cones long, longer than the segment in segment III; eyes prolonged ventrally ( Fig. 9 ); metanotum smooth around median pair of setae ( Fig. 13 ); fore tibiae brownish yellow ( Fig. 11 ), distinctly paler than femora; tube a little longer than head in female; fore wings shaded with brown......................................... elongatus sp. n.

Figures

FIGURES 1–7. Aesthesiothrips breviconus sp. n., female. (1) Head & prothorax; (2) eyes, ventral surface; (3) antenna; (4) prosternum & mesopresternum; (5) metanotum & pelta; (6) fore tibia and tarsus; (7) tube.

FIGURES 8–14. Aesthesiothrips elongatus sp. n., female. (8) Head; (9) eyes, ventral surface; (10); antena; (11) fore tibia and tarsus; (12) ferna & mesopresternum; (13) metanotum & pelta; (14) tube.

FIGURES 156–161. Ethirothrips tenuis sp. n., female. (156) Head & prothorax; (157) antennal segments III–VIII; (158) tube; (159) metanotum & pelta; (160) prosternum & mesopresternum; (161) fore tarsus.

FIGURES 15–20. Aesthesiothrips jatrophae, female. (15) Head & prothorax; (16) eye, ventral surface; (17) antenna; (18) fore tibia and tarsus; (19) metanotum & pelta; (20) tube.