Nandithrips, Rachana & Amarendra & Gracy & Nagarjuna Reddy, 2023

Rachana, Remani Rajan, Amarendra, Bellapu, Gracy, Ramasamy Gandhi & Nagarjuna Reddy, Katasani Venkata, 2023, A remarkable new genus of Thripinae (Thysanoptera, Thripidae) without anteocellar setae from India, ZooKeys 1141, pp. 65-73 : 65

Nandithrips gen. nov.

Type species.

Nandithrips pouzolziae sp. nov.

Description.

Female macroptera. Mouth-cone short and rounded at apex, with 3-segmented maxillary palpi. Ocellar setae pairs I and II absent. Antennae 8-segmented, segment I without median dorsal apical setae, III and IV with forked sensoria, III-VI with a few microtrichial rows (Fig. 5 ). Pronotum with two pairs of long posteroangular setae, outer pair shorter than inner pair; four pairs of posteromarginal setae, inner pair longer and thicker than the remaining pairs (Fig. 4 ). Mesonotum with median pair of setae anterior to submedian setae pair. Metanotum with median setae pair at or close to anterior margin, darker and stouter than sub median pair (Fig. 7 ). Prosternal ferna undivided, narrow at middle; basantra membranous and without setae; prospinasternum broad and transverse. Mesosternal furca with a spinula. Metasternal endofurca without spinula. Fore wing first vein with long gap in setal row, seven basal (first seta transparent) and three distal setae; clavus with five veinal and one discal setae; second vein with 6-9 setae; setae length on both veins increases abruptly beyond distal third of the forewing; posterior fringe cilia wavy (Fig. 8 ). Tarsi 2-segmented. Hind tibiae and tarsi each with two stout spines at apex. Abdominal tergites without ctenidia but a few microtrichia present on VIII anterolateral to spiracles, tergites without craspedum; tergites VI-VIII with S4 setae minute; tergite VIII with posteromarginal comb, microtrichia absent at middle (Fig. 12 ); tergite IX with two pairs of campaniform sensilla; tergite X with median slit more than two-thirds (Fig. 9 ); abdominal sternites without craspedum; sternite II with two pairs of posteromarginal setae, III-VII with three pairs, III-VI with S1, S2, and S3 at posterior margin, VII with S1 and S2 setae placed well ahead of posterior margin, S3 submarginal (Fig. 13 ). Sternites without discal setae. Ovipositor well developed.

Male macroptera. Abdominal tergite IX without median short and stout setae (Fig. 10 ); sternites II and V-VII each with a circular or oval pore plate medially (Fig. 11 ).

Etymology.

In reference to the type locality.

Generic relationships.

The absence of ctenidia on the abdominal tergites indicates that Nandithrips is not related to either the Thrips or Frankliniella genus groups ( Mound and Palmer 1981). However, Nandithrips shares the apomorphic character, the lack of ocellar setae pair II, only with the African genus, Bournierothrips Bhatti, which is a member of the Thrips genus group. This character state appears to be a convergence, as this genus does not belong to the same genus group. Bournierothrips has ctenidia and other character states of the Thrips genus group and the lack of the ocellar setae pair II seems to be an additional loss in that lineage which already lacks ocellar setae pair I. Even though both the genera share a unique apomorphic character within the subfamily Thripinae , they may not be closely related. The host plant association of the two genera appears to be different: this genus was collected in the flowers of Pouzolzia petandra subsp. wightii , but all described Bournierothrips species are associated with mosses, and the genus is endemic to Africa.

The lack of microtrichial fields laterally on the abdominal tergites indicates that this genus is not related to Scirtothrips genus-group ( Masumoto and Okajima 2007), and presence of long setae on the pronotum suggests that it is not related to Anaphothrips genus group ( Mound and Masumoto 2009). The general appearance of Nandithrips suggests that it is not related to Taeniothrips genus group even though it shares some character states like the absence of ocellar setae I and ctenidia ( Mound and Palmer 1981; Wang et al. 2020). The absence of a pair of dorsoapical setae on the first antennal segment indicates that it is not related to the two major genus-groups centred on Trichromothrips and Mycterothrips ( Masumoto and Okajima 2005, 2006), even though Nandithrips shares several characters with Trichromothrips genus group like the absence of ocellar setae pair I, ctenidia, craspeda, and discal setae on sternites and the position of S1 and S2 setae on sternite VII.

It is similar to the Old World flower-inhabiting genus, Lefroyothrips Priesner in colour, appearance, the absence of paired dorso-apical setae on antennal segment I, sculpture and chaetotaxy of the meso- and metanota, the absence of ctenidia and craspeda, and the presence of a group of microtrichia anterior to spiracle on abdominal segment VIII; however, Nandithrips is distinguished from Lefroyothrips in lacking ocellar setae pair I, the tergite VIII with the posteromarginal comb interrupted medially, the position of S2 setae on abdominal sternite VII, the pore gland shape and distribution on the sternites of males, and the stout thorn-like setae on tergite IX of males absent. Many of the characters of Nandithrips , particularly the absence of a pair of dorso apical setae on the first antennal segment, are shared with species of the flower-inhabiting genera Ceratothrips Reuter and Projectothrips Moulton. However, Nandithrips differs from Ceratothrips by lacking ocellar setae pair I, tergite VIII with the posteromarginal comb interrupted medially, the position of S1 and S2 setae on abdominal sternite VII, and the pore gland shape and distribution on the sternites of males. Projectothrips is a highly distinctive genus because of the elongate, slender, eighth antennal segment that is about nine times as long as wide. This genus shares several character states with the members of Megalurothrips genus group ( Craspedothrips zur Strassen, Megalurothrips Bagnall, Odontothripiella Bagnall, and Odontothrips Amyot & Serville) and Ceratothripoides Bagnall, Retanathrips Mound & Nickle, and Pezothrips Karny. However, the absence of a pair of dorsoapical setae on the first antennal segment indicates that it is not related to these genera. Even though Mound and Palmer (1981) included Ceratothripoides , Ceratothrips , Craspedothrips , Lefroyothrips , Megalurothrips , Odontothripiella , Odontothrips , and Projectothrips in the Megalurothrips genus group, Ceratothrips , Lefroyothrips , and Projectothrips may not belong in this group because of the absence of dorso-apical setae on antennal segment I ( Masumoto and Okajima 2020). Moreover, Zhang et al. (2019) showed in their phylogenetic analysis based on morphological data that Craspedothrips , Megalurothrips , and Odontothrips , genera with dorsoapical setae on antennal segment I, are included in the same clade and this clade was the sister-group to Mycterothrips Trybom, not Ceratothripoides . According to their analysis, Ceratothripoides seems to be the sister group of Pezothrips , but the systematic positions of these two genera are unresolved.

Mound and Palmer (1981) indicated that the absence of ocellar setae I is an apomorphic condition and presence/absence of this setae pair appears to be remarkably constant within genera and genus groups within the subfamily Thripinae . They also mentioned that ocellar setae pair II is remarkably constant in size and position. Hence, after examining multiple specimens (59 females, 22 males) of this genus, we assume that this apomorphic character, the absence of ocellar setae II, is constant within Nandithrips . Minaei and Mound (2021) stated that character-state reversals have often been interpreted as apomorphies, such that an unusual looking species is given separate taxonomic status on the basis of the absence of a single character state and, moreover, loss of a character occurs quite commonly. They also stressed the importance of evaluating a new taxon in relation to the structure of closely related taxa under circumstances of apparent absence or loss of a character state. Understanding well the depth of their observations, and after examining multiple specimens of both sexes, we ascertain that the absence of ocellar setae II is stable across all the examined specimens and looked for the other characters which justify its diagnosis as a new genus. One more character state which is unique to Nandithrips is the pore plate distribution in males, and this character is very important in discussing the novelty of taxa if males are known. In the subfamily Thripinae , wherever males are known, eight groups of pore plate distribution has been suggested: medially on sternites III + IV + V ( ± VI, VII, and VIII); medially only on sternites indicated (III, III-IV, and VII); C-shaped pore plate on sternites III + IV + V ( ± VI and VII); two or three pore plates on several sternites; multiple small pore plates on at least III-VI; on antecostal ridge of at least IV-VI (rarely only II); gland aperture on antecostal ridge of III (no pore plate), and pore plates or glandular structures absent ( Mound 2009). However, Nandithrips has a unique discontinuous pore plate distribution with a single circular or oval pore plate medially on sternites II and V-VII, and this condition is not shared with any of the genera in the subfamily Thripinae , wherever males are known. In the new genus, an abrupt increase in setae length on both the veins beyond the distal third of the fore wing is noticeable, which is also not shared with any other genera in the subfamily Thripinae .

To conclude, although Nandithrips is a member of the subfamily Thripinae , more precise relationships are not clear.

Figures

Figures 2 - 8. Nandithrips pouzolziae sp. nov. 2 female 3 male 4 prothorax 5 antenna 6 head 7 pterothorax 8 fore wing.

Figures 9 - 13. Nandithrips pouzolziae sp. nov. 9 female abdominal tergites IX-X 10 male abdominal tergites IX-X 11 pore plate on abdominal sternites II and V-VII 12 abdominal tergite VIII 13 abdominal sternite VII.