Haplothrips

Kucharczyk, Halina & Stanisławek, Kinga, 2020, Haplothrips second instar larvae (Thysanoptera: Phlaeothripidae); character states and key to Central European species, Zootaxa 4845 (3), pp. 375-392 : 385-387

Key to Haplothrips second instar larvae

[A measurement in parentheses after the indicated range for a structure is the most common condition not a mean]

1. Apices of most dorsal setae expanded or knobbed ( Figs 68–69 ), but shortest setae may be pointed or blunt ( Figs 66–67 ); sclerotization: sclerite pI on mesonotum usually wider than pII ( Figs 46–47 ); segment VIII with wide sclerotized band entirely surrounding spiracles ( Fig. 60 ); setae V2 on sternite XI usually more than 200 microns; red pigment distributed unevenly on head, prothorax, metathorax and abdominal segments I–IV, VII–X or entire body uniformly pale pink or orange ( Figs 22–26 ) ................................................................................................... 2

- Most setal apices pointed or blunt ( Figs 66–67 ); sclerotization less well-developed, mesonotal sclerites pI usually smaller than pII ( Fig. 45 ) or vestigial ( Fig. 44 ); setae V2 on abdominal sternite XI less than 200 microns; body colour uniformly red ( Fig. 21 )................................................................................................. 7

2. Head, thorax and abdomen uniformly light pink ( Fig. 22 ) or orange ( Fig. 23 ); most body setae knobbed ( Fig. 69 ); spiracle cells without pores ( Figs 79–82 a–c); setae long, especially D1 on head (more than 50 microns on average); mean length of meso- and metanotal setae D5>60 microns; setae V1 on abdominal segment VIII>80 microns............................. 3

- Red pigment distributed only within some body parts: head, prothorax, metathorax and abdominal segments I–IV, VII–X ( Figs 24–26 ), rest of body white or cream; most setal apices expanded ( Fig. 68 ); spiracle cells with pores ( Figs 75, 77 a–c); setae generally shorter...................................................................................... 4

3. Antennae bicoloured, darkening towards apex ( Fig. 35 ), segments I–III usually pale (or II darker), IV dark on distal half, V–VII wholly dark; sclerotization around body setae less well-developed ( Fig. 52 ); pronotal sclerites trapezoidal ( Fig. 34 ); pronotal seta D1 bent ( Fig. 34 ); pronotal setae D5 and D6>80 microns; meso- and metanotal setae D1–D3 50–60 microns. [Europe, Near East, North Africa, North America; leaves and stems of Verbascum spp.]............................... verbasci

- Antennae usually uniformly dark ( Fig. 36 ); sclerotization around body setae well developed ( Fig. 53 ); pronotal sclerites almost rectangular with straight inner margins ( Fig. 33 ); metasternum sometimes with additional pair of small sclerites ( Fig. 48 ); pronotal setae D5 and D6 60–70 microns; meso- and metanotal setae D1–D3 20–40 microns. [Palearctic; flowers of various Asteraceae species eg. Cirsium , Carduus & Knautia spp.].......................................... distinguendus

4. Only abdominal segments VII–X red; rest of body cream or yellowish ( Fig. 24 ); sculpture of cuticle from prothorax to end of abdomen very distinct, clearly visible on both dorsal and ventral surfaces ( Fig. 43 ); antennae 200–235 microns long, segment VI 1.2–1.7 times as long as wide......................................................................... 5

- Red colour usually present on head, thorax and anterior abdominal segments as well as VII–X ( Fig. 26 ); sculpture of cuticle less distinct, better developed ventrally on distal segments; antennae 237–295 microns long, segment VI 1.7–3.1 times as long as wide............................................................................................. 6

5. Cephalic setal apices expanded ( Fig. 68 ); antennal segment V 1.3–1.7 as long as wide; abdominal segment IX setae: apex of D1 lanceolate (= flattened at some length), D2 forked ( Figs 70–71 ), both 50–62 microns long; seta V1 pointed (85–110 microns long). [Holarctic into Oriental region; inflorescences of Poaceae , including cereal crops such as Secale cereale ]... aculeatus

- Cephalic setal apices pointed ( Fig. 66 ); antennal segment V about 1.9 times as long as wide; abdominal segment IX setae: apex of D1 and D2 expanded (respective lengths 83 and 33 microns); seta V1 pointed (about 55 microns long). [Europe, Near East, North Africa; on Juncaceae and Cyperaceae ]......................................................... juncorum

6. Head, prothorax, metathorax and abdominal segments III, IV and VII–X red, remaining segments white or cream ( Fig. 25 ); antennae pale, segments I–II slightly darker, III paler, IV–VII darker apically ( Fig. 38 ); antennal segments III and IV 2.5–3.0 times as long as wide; abdominal segment IX setae: D1 flattened at some length (length 80–90 microns, Fig. 70 ), D2 forked (length 80–98 microns, Fig. 71 ); maxillary palps 30–35 microns long; spiracle cells mainly with 2–3 pores; mesosternum sometimes with additional pair of small sclerites ( Fig. 49 ). [Europe; on leaves of trees and shrubs as predator]....... subtilissimus

- Head, prothorax and abdominal segments VII–X red, sometimes also I and/or II ( Fig. 26 ); antennae dark, segments III and IV 2.1–2.4 times as long as wide; abdominal segment IX setae: D1 pointed (102–132 microns long); D2 expanded (41–55 microns long); maxillary palps 22–27 microns long; spiracle cells with one pore ( Figs 77 a–c). [Palearctic; thermophilic, flowers of Armeria maritima , Scleranthus perennis , Jasione montana ].......................................... acanthoscelis

7. Posterior margins of pronotal sclerites reduced medially ( Fig. 31 ), setae D1 close margin; mesonotal sclerites pII absent ( Fig. 44 ); antennal segments III–V 1.4–1.7 times as long as wide ( Fig. 41 ); setae D2 on head 9–16 microns long; maxillary palps 7–17 microns long, meso- and metanotal setae D5 47–74 microns long........................................... 8

- Posterior margins of pronotal sclerites well-developed with sclerotization around setae D1 ( Fig. 32 ); two pairs of mesonotal sclerites generally present, second pair wider than first ( Fig. 45 ); antennal segments III–V nearly 2.0 times as long as wide; setae D2 on head 12–35 microns long; maxillary palps 15–21 microns long, meso- and metanotal setae D5 53–100 microns long................................................................................................ 9

8. Sternite VIII sclerotized band extends far beyond seta V2 or entirely fused with seta V1 ( Fig. 59 ); cephalic setae, also segment IX setae D2 and V2 pointed; setal lengths: D1 on head (23–32 microns), D4 on pronotum (22–35 microns), V1 on abdominal sternite IX (62–75 microns). [Palearctic, flowers of Achillea millefolium ]............................... angusticornis

- Sternite VIII sclerotized band not extending between setae V1 and V2, very weak around setae V1 ( Fig. 55 ); cephalic setae, also D2 and V2 on segment IX blunt; setal lengths: D1 on head (27–41 microns), D4 on pronotum (33–50 microns), V1 on abdominal sternite IX (72–95 microns). [Central Europe to Eastern Palearctic; on Helichrysum arenarium ]....... arenarius

9. Body length about 2.5 mm; distance between antennae 17–25 (usually 20) microns; setal lengths: D1 on tergite IX (105–122 microns) (usually 111), V2 on sternite X 157–212 microns (usually 194), head seta D2 (27–35 microns) (usually 31), mesonotal setae D2 and D3 (30–40 microns). [Europe; thermophilous, flowers of Dianthus sp.]......................... dianthinus

- Body length 1.2–2.3 mm; distance between antennae 10–24 microns; setal lengths: D1 on tergite IX (50–100 microns), V2 on sternite X (100–180 microns), D2 on head (12–30 microns), D2 and D3 on mesonotum (15–37 microns)............... 10

10. Sternite VIII sclerotization not extending between setae V1 and V2, very weak around setae V1 ( Fig. 55 ); fore tibia terminal seta pointed or blunt ( Fig. 72 ); tergite II spiracle length/width not exceeding 15 microns, comprising 3–9 cells; setal lengths: D1 on head (48–67 (56) microns), V1 on abdominal sternite VIII (70–95 (81) microns)............................. 11

- Sternite VIII sclerotization not usually extending between setae V1 and V2, well developed around setae V1 ( Fig. 61 ); fore tibia terminal seta capitate ( Fig. 73 ); tergite II spiracle length/width greater than 15 microns, comprising 7–22 cells; setal lengths: D1 on head (35–56 (44) microns), V1 on abdominal sternite VIII (60–88 (73) microns)................................ 12

11. Tergite VIII sclerotization not usually complete between setae D1 and D2 or around campaniform sensilla and spiracles ( Fig. 54 ); metasternum sometimes with additional pair of small sclerites ( Fig. 50 ); setal lengths: V2 on abdominal segment VIII (22–32 (26) microns); D2 (40–55 (46) microns), V2 on abdominal segment IX (42–55 (48) microns). [Europe to Western Asia; inflorescences of Poaceae including cereals such as Triticum vulgare ]......................................... tritici

- Tergite VIII sclerotization usually complete between setae D1 and D2, and around campaniform sensilla and spiracles ( Figs 58, 60 ); setal lengths: V2 on abdominal segment VIII (16–28 (19) microns); D2 30–45 (37) microns, V2 on abdominal segment IX 27–47 (39) microns. [Palearctic, central Europe, Near East, North Africa; inflorescences of Bromus tectorum , B. hordeaceus ].............................................................................................. cerealis

12. Most dorsal setae blunt ( Fig. 67 ), including D1, D2 and V3 on abdominal segment VIII and D1 on abdominal tergite IX; seta V1 on sternite IX 57–80 microns long.................................................................... 13

- All setae pointed ( Fig. 66 ), including on abdominal segments VIII and IX; seta V1 on abdominal sternite IX 75–114 microns long............................................................................................... 14

13. Seta V2 on abdominal sternite IX 30–55 (39) microns long; antenna 225–263 (245) microns long; head seta D1 usually blunt. [Europe; thermophilic, flowers of Jasione montana ]..................................................... jasionis

- Seta V2 on abdominal sternite IX 19–30 (24) microns long; antenna 200–245 (230) microns long; head seta D1 pointed. [Palearctic; flowers of Asteracae]......................................................................... setiger

14. Tergite II spiracles with 7–9 cells; terminal abdominal setae short, segment IX D1 (62–77 (69) microns), V2 (25–42 (34) microns), V2 on sternite XI (97–131 (113) microns). [Europe; thermophilic, flowers of P. argentea]............ setigeriformis

- Tergite II spiracles with 6–22 cells; terminal abdominal setae longer, segment IX D1 (72–100 (81) microns), V2 (32–60 (48) microns), V2 on sternite XI (118–183 (145) microns)........................................................ 15

15. Tergite VIII sculpture well developed (teeth also present between setal pairs of D1 or V1, Fig. 56 ); D5 setae on meso- and metanotum 60–100 (82) microns, sternite VIII setae V2 (15–37 (24) microns), V3 (length 56–97 (71) microns). [Europe; flowers of Armeria maritima ]............................................................................... statices

- Tergite VIII sculpture weakly developed (teeth not present between setal pairs of D1 or V1 or with a few teeth laterally in this area); D5 setae on meso- and metanotum 55–82 (68) microns), abdominal sternite VIII V2 (11–21 (16) microns), V3 (47–78 (57) microns). [Palearctic; flowers of Leucanthemum vulgare ]......................................... leucanthemi

Figures

FIGURES 62–73. Haplothrips larvae structural details. Segment X shape and sculpture (under SEM and light microscope) 62– 65: (62–63) arenarius; (64–65) distinguendus. Dorsal setae on head, thorax and abdominal segments I–VIII (left image—light microscope, right image—SEM) 66–69: (66) acute; (67) blunt; (68) expanded; (69) knobbed. Setae on Abdominal segment IX setae 70–71: (70) seta D1 lanceolate (flattened at some length); (71) setae D2 and V2 forked. Setae on fore tibia 72–73: (72) acute or blunt; (73) capitate.

FIGURES 42–47. Haplothrips larvae sculpture and sclerotization. Abdominal segments 42–43: (42) statices; (43) aculeatus. Meso- and metanotum sclerotized dorsal plates 44–47: (44) arenarius; (45) cerealis; (46) aculeatus; (47) verbasci.

FIGURES 54–61. Haplothrips larvae segment VIII sclerotization and sculpture. Abdominal tergite (left) and sternite (right). (54) arenarius tergite; (55) tritici sternite; (56) statices tergite; (57) aculeatus sternite; (58) distinguendus tergite; (59) angusticornis sternite; (60) verbasci tergite; (61) verbasci sternite.

FIGURES 21–26. Haplothrips larvae body colour. (21) setiger; (22) distinguendus; (23) verbasci; (24) aculeatus; (25) subtilissimus; (26) acanthoscelis.

FIGURES 74–82. Haplothrips larvae spiracles (a—on mesonotum, b—on tergite II, c—on tergite VIII; light microscope 74– 80; SEM 81–82). (74) jasionis; (75) aculeatus; (76) statices; (77) acanthoscelis; (78) arenarius; (79) verbasci; (80) dianthinus; (81) distinguendus; (82) leucanthemi.

FIGURES 35–41. Haplothrips larvae antennal segments. (35) verbasci; (36) statices; (37) jasionis; (38) subtilissimus; (39) arenarius; (40) aculeatus; (41) angusticornis.

FIGURES 48–53. Haplothrips larvae sclerites. Meso- and metasternum 48–50: (48) distinguendus; (49) subtilissimus; (50) tritici. Abdominal dorsal setae basal sclerotizations 51–53: (51) arenarius; (52) dianthinus; (53) aculeatus.

FIGURES 27–34. Haplothrips larvae sclerotized plates. Frons central small plate 27–30: (27) setigeriformis; (28) arenarius; (29) aculeatus; (30) verbasci. Prothorax dorsal plates 31–34: (31) arenarius; (32) leucanthemi; (33) aculeatus; (34) verbasci.