Ethirothrips Karny

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 : 16-19

publication ID	https://doi.org/ 10.11646/zootaxa.5291.1.1
publication LSID	lsid:zoobank.org:pub:34500B9B-694C-49EE-A194-609AC6A617C7
DOI	https://doi.org/10.5281/zenodo.7971652
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scientific name	Ethirothrips Karny
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Ethirothrips Karny View in CoL

Liothrips (Ethirothrips) Karny, 1925: 133 . Type-species: Liothrips thomasseti Bagnall View in CoL , by subsequent designation, Priesner, 1949: 129.

Ethirothrips is highly diverse and weakly defined genus in the Macrothripina with seven generic synonyms. The genus involved 38 species in the world before this work, of which 33 species were described from the Australian and Oriental Regions including some Pacific Islands, four species from the Afrotropical Region, and only one species from the Neotropical Region. Similar to most genera belonging to the Macrothripina , Ethirothrips is undoubtedly of Old World origin, and is extremely diversified in the region from India to Australia. Previously, only ten species were recorded from Peninsular Malaysia to Taiwan: E. brevis , E. indicus , E. obscurus E. rubeus , E. virgulae and E. yangi from Taiwan; E. longisetis from Hainan, China; E. vitreipennis from Hainan and Fujian, China; E. stenomelas and E. tibialis from relatively wide range of this area. However, the records of four species, brevis , indicus , obscurus and vitreipennis , have some problems which are discussed under each species. In this study, an additional 16 species are newly described from Southeast Asia to Taiwan. As a result, 54 species are now included in this genus, of which 26 species are currently recorded from Southeast Asia to Taiwan. Morphological character states of these species seem to be complicated and diversified. Unfortunately, individual character states among Ethirothrips species show continuous changes in most cases, and no species acquired apomorphies important enough to divide the genus.

Structural variations among Ethirothrips species :

1) Head: E. australiensis from Australia and E. quadratus have shorter heads (cf. Fig. 115 View FIGURES 115–120 ) which are almost as long as broad or only a little longer, though E. longiceps and E. tenuis has the head elongate ( Figs 69 View FIGURES 69–76 & 156 View FIGURES 156–161 ) and about 2.0 times as long as broad or a little longer. E. malaya and the species described under the synonymous genus Uredothrips , such as E. tibialis , have the heads elevated dorsally ( Figs 43 View FIGURES 43–48 , 84 View FIGURES 84–89 & 176 View FIGURES 176–181 ), and this structure is shared with Aesthesiothrips and Celidothrips species. Furthermore, E. colossus has the head weakly protruded forwardly ( Fig. 36 View FIGURES 36–42 ), but E. agasthya from India and E. antennalis from Japan have somewhat intermediate heads which are scarcely protruded.

2) Cephalic seta: Most species have one pair of long setae on the dorsum of head, the postoculars, but some species, such as E. indicus , E. ommatus , E. puiensis and E. obscurus , have a pair of long postocellar setae in addition to the postoculars (cf. Fig. 104 View FIGURES 104–109 ). The postocellar setae are usually situated behind a pair of posterior ocelli, but they are situated between the posterior ocelli in E. thai and E. yangi (cf. Fig. 169 View FIGURES 169–175 ).

3) Ommatidium-like structure: At least certain species, such as E. longiceps , E. ommatus and E. stenomelas , have an ommatidium-like structure on each cheek, but there is a possibility that it is merely difficult to see if it is formed flat-circular and situated laterally and is present in more (or most) species. This structure is shared with some genera among the Macrothripina , such as Celidothrips , Peltariothrips , Polytrichothrips and Tarassothrips . This structure is mostly situated just behind the compound eyes on each cheek, but it is situated between the base and middle of the cheek in Peltariothrips and Polytrichothrips and even in E. ommatus ( Figs 104b View FIGURES 104–109 & 204 View FIGURES 203–210 ).

4) Antenna: Usually 8-segmented, but E. fijiensis has unusual 7-segmented antennae with segments VII and VIII completely fused without suture between them. Segment III is mostly longer than segment IV and with relatively short sense-cones, but it is shorter than IV and with extremely long and curved sense-cones in E. indicus and E. rubeus (cf. Fig. 122 View FIGURES 121–126 ). This condition of antennal segment III short with long and curved sense-cones is shared with some species placed in some other genera within the Macrothripina , such as Aesthesiothrips and Tarassothrips . E. colossus has antennal segment III slender and 4.5–5.0 times as long as broad ( Fig. 37 View FIGURES 36–42 ), though it is 2.0–3.5 times as long as broad in most species (cf. Figs 50 View FIGURES 49–55 & 111 View FIGURES 110–114 ). However, it is somewhat intermediate in some species, such as E. longisetis and E. (?) stenomelas from Mindanao (cf. Figs 80 View FIGURES 77–83 & 150 View FIGURES 149–155 ). The segment VIII is mostly short, conical and scarcely constricted basally, but it is long and pedicellate in E. colossus , and E. malaya ( Figs 37 View FIGURES 36–42 & 85 View FIGURES 84–89 ). However, E. oculus and E. setosus have somewhat intermediate ones ( Figs 99 View FIGURES 96–103 & 135 View FIGURES 133–140 ).

5) Sense-cone formula: Usually two and four sense-cones on antennal segments III and IV, respectively. However, a few species, such as E. longiceps and E. stenomelas , have segment IV with a small dorsal one in addition to the four usual sense-cones, and a similar sense-cone formula is also found in Diaphorothrips and Tarassothrips species ( Tarassothrips akritus has three small dorsal sense-cones, but T. grandis has no small dorsal one).

6) Maxillary stylet: Although most species have V-shaped maxillary stylets which scarcely reach the postocular setae or not, some species, such as E. conopygus , E. malaya , E. saigon and E. tibialis , have the stylets relatively close and parallel (or subparallel) stylets that reach the compound eyes (cf. Figs 43 View FIGURES 43–48 & 84 View FIGURES 84–89 ). However, E. colossus and E. puiensis have similar subparallel stylets, but they are not so long (cf. Fig. 110 View FIGURES 110–114 ) and somewhat intermediate. Particularly, E. tenuis has stylets which are long and close together medially ( Fig. 156 View FIGURES 156–161 ).

7) Pelta: Most species have the pelta trilobed (cf. Figs 52 View FIGURES 49–55 , 79 View FIGURES 77–83 & 94 View FIGURES 90–95 ) or broadly triangular (cf. Figs 38 View FIGURES 36–42 , 102 View FIGURES 96–103 & 119 View FIGURES 115–120 ), but some species have the pelta of intermediate shape (cf. Figs 65 View FIGURES 62–68 & 107 View FIGURES 104–109 ). Interestingly, E. longiceps has an almost triangular pelta ( Fig. 73 View FIGURES 69–76 ) with the lateral corners recurved which is somewhat similar to those of Diaphorothrips species, and E. tenus has the pelta irregularly triangular ( Fig. 159 View FIGURES 156–161 ) and very similar to those of Aesthesiothrips species. These may suggest that Ethirothrips is related to these two genera.

8) Tube: Most species have the tube almost as long as head or a little shorter, but some species, such as E. indicus and E rubeus have the tube much longer than head (cf. Figs 231 & 232 View FIGURES 223–234 ). Some species, such as E. setosus and E. stenomelas , have rather slender tube (cf. Figs 137 View FIGURES 133–140 & 143 View FIGURES 141–147 ), though E. conopygus has the tube somewhat heavy, short and conical ( Fig. 48 View FIGURES 43–48 ). Particularly, E. tenuis has the slender tube parallel-sided with distinct constriction at apex ( Fig. 158 View FIGURES 156–161 ). Terminal setae usually shorter than tube, but rarely almost as long as tube or a little longer.

This genus, therefore, appears to be extremely difficult to define, and it is here tentatively defined in somewhat broader sense as follows.

Diagnosis. Medium to large sized species of Macrothripina . Head variable in length, 1.0–2.0 times as long as broad; cheeks often each with an ommatidium-like structure, but sometimes difficult to observe. A pair of postocular setae well developed; ocellar setae usually minute, but postocellars often elongate. Antennae 8-segmented, rarely 7-segmented; segment III usually longer than IV, rarely shorter than IV; segment III with two, segment IV with four sense-cones (rarely with additional small one). Mouth cone short and rounded; maxillary stylets variable, usually V-shaped, often closer together, sub-parallel or rarely close together medially. Prothoracic notopleural sutures complete. Fore femora unarmed in both sexes; fore tibiae often with an inner apical tubercle or tooth; fore tarsal tooth usually present in both sexes. Metanotal median setae short. Pelta trilobed or broadly triangular. Tube variable, short or long, often somewhat heavy.

Key to Ethirothrips species View in CoL from Southeast Asia to Taiwan

(*: E. indicus and E. vitreipennis are based on descriptions)

1. Antennal segment IV with a small dorsal sense-cone in addition to regular four sense-cones; head longer than 1.8 times as long as broad............................................................................................. 2

- Not above combination of features........................................................................ 4

2. Fore tibia with an inner apical tubercle in both sexes ( Figs 71 & 72 View FIGURES 69–76 ); pelta triangular, without distinct lateral wings, somewhat similar to that of Diaphorothrips View in CoL ( Fig. 73 View FIGURES 69–76 ); tube distinctly constricted at apex ( Fig. 76 View FIGURES 69–76 ).................. longiceps sp. n.

- Fore tibia without inner apical tubercle; pelta with distinct lateral wings: tube scarcely constricted at apex............... 3

3. Antennal segment III more than 3.5 times as long as broad ( Fig. 150 View FIGURES 149–155 ); postocular setae situated behind inner margin of eyes ( Fig. 148 View FIGURE 148 ); fore wing with more than 55 duplicated cilia; tube more than 4.2 times as long as broad ( Fig. 155 View FIGURES 149–155 )........................................................................... (?) stenomelas View in CoL (from Mindanao and East Java)

- Antennal segment III less than 2.8 times as long as broad ( Fig. 142 View FIGURES 141–147 ); postocular setae wider apart ( Fig. 141 View FIGURES 141–147 ); fore wing with less than 45 duplicated cilia; tube less than 4.0 times as long as broad ( Fig. 143 View FIGURES 141–147 ).............................. stenomelas View in CoL

4. Head longer than 1.8 times as long as broad................................................................ 5

- Head shorter than 1.6 times as long as broad................................................................ 8

5. Head swollen dorsally ( Fig. 84 View FIGURES 84–89 ); maxillary stylets deeply retracted to eyes; antennal segments short, segment III shorter than 3.0 times as long as broad ( Fig. 85 View FIGURES 84–89 ); anterior margin of pronotum rather straight, not emarginate ( Fig. 84 View FIGURES 84–89 ); metanotum distinctly sculptured with concentric reticulation ( Fig. 87 View FIGURES 84–89 ); tube short and heavy ( Fig. 89 View FIGURES 84–89 ), about 2.1 times as long as broad, much shorter than head.................................................................................. malaya sp. n.

- Not as above......................................................................................... 6

6. Head projected shortly in front of eyes ( Fig. 36 View FIGURES 36–42 ); antennal segment III unusually long, much longer than 4.0 times as long as broad ( Fig. 37 View FIGURES 36–42 ); maxillary stylets closer than postocular setae, sub-parallel, but not reaching eyes........... colossus sp. n.

- Head not projected in front of eyes; antennal segment III shorter than 4.0 times as long as broad; maxillary stylets not above. ................................................................................................... 7

7. Maxillary stylets short and wide apart, retracted to middle of head ( Fig. 134 View FIGURES 133–140 ); head shorter than 2.0 times as long as broad; tube tapering, scarcely constricted apically ( Fig. 137 View FIGURES 133–140 ); pelta broadly triangular ( Fig. 136 View FIGURES 133–140 ), somewhat similar to that of Machatothrips species, antero-median angle obtuse............................................................ setosus sp. n.

- Maxillary stylets long and close together medially, retracted to eyes ( Fig. 156 View FIGURES 156–161 ); head longer than 2.0 times as long as broad; tube sub-parallel, distinctly constricted apically ( Fig. 157 View FIGURES 156–161 ); pelta triangular, somewhat similar to that of Aesthesiothrips species, antero-median angle acute ( Fig. 159 View FIGURES 156–161 )............................................................. tenuis sp. n.

8. Maxillary stylets sub-parallel (cf. Figs 43 View FIGURES 43–48 & 110 View FIGURES 110–114 )............................................................ 9

- Maxillary stylets V-shaped (cf. Figs 49 View FIGURES 49–55 & 62 View FIGURES 62–68 ).............................................................. 12

9. Tube longer than head; postocellar setae elongate ( Fig. 110 View FIGURES 110–114 ), usually longer than 1/2 length of postoculars.... puiensis sp. n.

- Tube shorter than head; postocellar setae minute, usually shorter than a diameter of posterior ocellus.................. 10

10. Cheeks distinctly constricted from behind the middle to base ( Fig. 127 View FIGURES 127–132 ); pronotal am setae developed, more than 50μm............................................................................................... saigon sp. n.

- Cheeks almost straight, sub-parallel or weakly evenly narrowed to base (cf. Fig. 43 View FIGURES 43–48 ); pronotal am setae short, 30μm or shorter .................................................................................................. 11

11. Tube short and conical, about 0.6 times as long as head, about 1.6 times as long as broad ( Fig. 48 View FIGURES 43–48 ); fore tibia with a forwardly directed small inner apical tubercle ( Fig. 46 View FIGURES 43–48 ); S2 setae on abdominal segment IX slightly longer than tube.. conopygus sp. n.

- Tube more than 0.75 times as long as head, more than 2.1 times as long as broad ( Fig. 178 View FIGURES 176–181 ); fore tibia with a laterally directed small inner sub-apical tubercle ( Fig. 179 View FIGURES 176–181 ); S2 setae on abdominal segment IX shorter than tube................... tibialis View in CoL

12. Antennal segment III shorter than segment IV ( Fig. 122 View FIGURES 121–126 ); sense-cones unusually long and curved, longer than 2/3 length of the segment............................................................................................ 13

- Antennal segment III longer than segment IV; sense-cones shorter............................................. 14

13. Head about 1.1 times as long as broad; postocellar setae usually longer than diameter of an ocellus, 35–65μm; fore wing with 32–40 duplicated cilia............................................................................ indicus View in CoL *

- Head longer than 1.2 times as long as broad; postocellar setae minute, usually shorter than a diameter of ocellus; fore wing with 15–26 duplicated cilia............................................................................. rubeus

14. Metanotum with a pair of CPS ( Fig. 34 View FIGURES 32–35 ); antennal segment III yellow, weakly shaded with brown distally, segment IV pale brown; fore tibia yellow to yellowish brown, distinctly paler than fore femur.................................. brevis View in CoL

- Metanotum without CPS; colour of antennal segments III–IV and fore tibia variable............................... 15

15. Postocellar setae situated between posterior ocelli (cf. Fig. 169 View FIGURES 169–175 )............................................... 16

- Postocellar setae situated behind posterior ocelli (cf. Fig. 104 View FIGURES 104–109 )................................................. 17

16. Basal 1/2 of antennal segment V yellow ( Fig. 187 View FIGURES 182–189 ); fore tarsal tooth very small in female, but developed in male; fore wings distinctly shaded with brown; lateral wings of pelta narrowly fused to median lobe ( Fig. 188 View FIGURES 182–189 )...................... yangi

- Antennal segment V brown, often slightly paler on basal 1/2; fore tarsal tooth well-developed in both sexes; fore wings scarcely shaded with brown; lateral wings of pelta widely fused to median lobe ( Fig. 173 View FIGURES 169–175 )............................ thai sp. n.

17. Postocular setae rather close together, situated behind inner margin of eyes...................................... 18

- Postocular setae wider apart, situated behind eyes........................................................... 19

18. Head ( Fig. 78 View FIGURES 77–83 ) more than 1.50 times as long as broad; postocular setae usually longer than 210μm in female, longer than 170μm in male; cheek with some stout setae; fore femora with a series of long and slender setae in addition to a regular dorso-external seta ( Fig. 77 View FIGURES 77–83 ); tube rather slender, more than 3.3 times as long as broad ( Fig. 81 View FIGURES 77–83 )............................ longisetis View in CoL

- Head less than 1.45 times as long as broad; postocular setae shorter than 200μm in female, shorter than 160μm in male; cheeks without stout setae; fore femora without long and slender setae in addition to a regular dorso-external seta; tube less than 3.0 times as long as broad ( Fig 184 View FIGURES 182–189 ).................................................................... virgulae View in CoL

19. Pelta broadly triangular, similar to those of Machatothrips species (cf. Figs 107 View FIGURES 104–109 & 119 View FIGURES 115–120 )............................. 20

- Pelta trilobed, lateral wings narrowly or broadly fused to median lobe, at least lateral wings distinct from median lobe (cf. Figs 52 View FIGURES 49–55 & 94 View FIGURES 90–95 )........................................................................................... 22

20. Head short, about 1.1 times as long as broad ( Fig. 115 View FIGURES 115–120 )........................................... quadratus sp. n.

- Head elongate, more than 1.4 times as long as broad........................................................ 21

21. Fore tarsal tooth absent in female ( Fig. 100 View FIGURES 96–103 ); cheeks without ommatidium-like structure on at least behind the middle; postocellar setae minute, shorter than diameter of a posterior ocellus............................................. oculus sp. n.

- Fore tarsal tooth present in female ( Fig. 108 View FIGURES 104–109 ); cheeks each with a small ommatidium-like structure at basal 1/3 ( Fig. 104b View FIGURES 104–109 ); postocellar setae elongate, but variable in length, usually longer than 2/3 of postoculars................... ommatus sp. n.

22. Postocellar setae elongate ( Fig. 90 View FIGURES 90–95 ), much longer than diameter of a posterior ocellus; antennal segments III and IV yellow ( Fig. 92 View FIGURES 90–95 ); fore wings clear............................................................................. obscurus View in CoL

- Not above combination of features....................................................................... 23

23. Terminal setae almost as long as tube, or a little longer............................................ terminali s sp. n.

- Terminal setae much shorter than tube.................................................................... 24

24. Pronotal aa setae longer than am; S1 setae on abdominal tergite IX shorter than tube...................... dalatae sp. n.

- Pronotal am and aa setae short and subequal in length; S1 setae on abdominal tergite IX almost as long as tube, or a little longer............................................................................................. 25

25. Antennal segments III and IV largely yellow ( Fig. 63 View FIGURES 62–68 ); fore tibiae yellowish, much paler than fore femora... kasetsarti sp. n.

- Antennal segments III and IV largely brown, but basal 1/3 of segment III often paler; fore tibia yellowish brown to brown... .................................................................................................. 26

26. Head shorter than 1.3 times as long as broad; antennal segment III shorter than 2.5 times as long as broad; anterior margin of pelta pointed medially at an acute angle ( Fig. 59 View FIGURES 56–61 ); fore wings shaded with brown, usually with 9–12 duplicated cilia.............................................................................................. duricaudus sp. n.

- Head about 1.5 times as long as broad, or longer; antennal segment III about 3.0 times as long as broad; anterior margin of pelta pointed medially at an obtuse angle; fore wings almost clear, with 15–19 duplicated cilia.................. vitreipennis View in CoL *