Eosentomon chiangmaiense Nakamura & Likhitrakarn

Nakamura, Osami & Likhitrakarn, Natdainai, 2009, Protura (Hexapoda) from Doi Suthep-Pui National Park, Chiang Mai, Thailand, Zootaxa 2121, pp. 1-16 : 11-15

Eosentomon chiangmaiense Nakamura & Likhitrakarn sp. nov.

Figures 6–7 , Table 3.

Type material examined. Holotype Ƥ, 2 paratype 3, mixed forest; 2 paratype 3, 1 paratype Ƥ, evergreen forest; 2 paratype 3, 2 paratype Ƥ, plantation. The holotype (CMUZ-1393) and 4 paratypes (2 3, 2 Ƥ: CMUZ- 1394–1397) are deposited in the collection of the Chulalongkorn University Museum of Zoology, Bangkok, and 5 paratypes (4 3, 1 Ƥ; NSMT-Ap 445–449) are in the collection of the National Science Museum, Tokyo.

Other specimen examined. One larva II, evergreen forest.

Description. Body length 977 (805–1009) μm.

Head 147 (139–150) μm long, (90–) 110 μm wide. Anterior additional seta (aa) absent; posterior additional seta (pa), anterior sensillum (as), posterior sensillum (ps), seta m4 present ( Fig. 6 A); subposterior seta 1.4 times longer than posterior seta; sensillum posterior to pseudoculus rudimentary. Labral setae present ( Fig. 6 B); rostral setae simple, shorter than subrostral setae ( Fig. 6 B). Clypeal apodeme distinct ( Figs. 6 A, B). On maxillary palpus, dorsal (d) and lateral (l) sensilla similar in shape and length ( Fig. 6 C). Outer (O) digit of galea longer than middle (M) and inner (I) digits; M and I similar ( Fig. 6 D). Mandible with two teeth ( Fig. 6 E). Pseudoculus ovoid, with central depression and a line ( Fig. 6 F), 13–16 μm long, 10 μm wide, PR = 10.3–11.5.

Foretarsus length 65 (–73) μm; claw 16 (15–18) μm, TR = 4.4 (3.9–4.6); empodium (15–) 18 μm, EU = (0.9–) 1.1; seta s 17 (16–18) μm, subequal to claw in length ( Figs. 6 G, H). Sensillum t1 about halfway between α3 and α3', BS = (0.9–) 1.1; t2 thin and relatively long, reaching base of α5; t3 thick, reaching pretarsus; a of medium size, not reaching base of γ 2; b and c linear; d broad, tapering distally, its apex reaching base of α6; e and g with spatulate dilation about half of sensillum length; f1 thin, reaching base of γ5; f2 short; a' relatively long, passing base of t2; b'1 absent; b'2 reaching base of α6; c' absent. Length of middle tarsus 33 (31–34) μm, claw (10–) 11 μm; hind tarsus 39 (–42) μm, claw (11–) 12 μm; both empodia short, less than 2 μm ( Fig. 6 I); on hind tarsus seta D2 slender, spine-like, D5 thick, spine-like ( Fig. 6 I).

Larva II Imago Formula Composition of setae Formula Tertiary and complementary setae

(Dorsal)

Thorax I 4 1, 2 4

II 6 A2, 4, M 6

14 P1, 1a, 2, 2a, 3, 4, 5 16 P3a

III 6 A2, 4, M 6

16 P1, 1a, 2, 2a, 3, 4, 4a, 5 18 P3a

Abdomen I 0 4 A1, 2 12 P1, 1a, 2, 3, 4, 5 12

II 0 10 A1, 2, 3, 4, 5 16 P1, 1a, 2, 2a, 3, 4, 4a, 5 16

III 2 A4 10 A1, 2, 3, 4, 5 16 P1, 1a, 2, 2a, 3, 4, 4a, 5 16

IV 4 A4, 5 10 A1, 2, 3 16 P1, 1a, 2, 2a, 3, 4, 4a, 5 16

V–VII 4 A4, 5 4

16 P1, 1a, 2, 2a, 3, 4, 4a, 5 16

VIII 6 M2, 4, 5 6

9 Pc, 1a, 1a’, 2, 2a 9

IX 8 1, 2, 3, 4 8

X–XI 8 1, 2, 3, 4

III 6–2 A1, 2, 3, M1 6–4 M2 – – 8 P1, 2, 2a, 3

Abdomen I 4 A1, 2 4

3 (P1), 2 3

II–III 4 A1, 2 6 A3 3 (P1), 2 3

IV – – 6 A1, 2, 3 – – 9 (P1), 2, 2a, 2a’, 3

V–VII 4 A1, 2 6 A3 7 (P1), 2, 2a, 3 9 P2a’

VIII 0 0

7 Pc, 1, 1a, 2 7

IX 4 1, 2 4

X 4 1, 2

XI 8 1, 2, 3, 4

Telson 12 12

Chaetotaxy as in Fig. 7 and Table 3. On thoracic tergites II–III, P1a situated slightly posterior to line of P1–P2, seta-like; P2a subequal to P3a, P3a on line of P3 –P4, setiform ( Fig. 7 A). Thoracic tergite III with P4a setiform, P5 minute ( Fig. 7 A). Abdominal tergites II–IV with five pairs of anterior setae; V–VII with two pairs of setae, (A4, A5); X–XI with four pairs. P1a and P2a on abdominal tergites I–VI and P2a on VII situated posterior to line of P1–P2, hair-like ( Fig.7 B, C); on VII P1a situated on same line as P1–P2, near P2, sensillum-like and short ( Fig. 7 C); on VIII, P1a' without basal dilatation; P2a' linear ( Fig. 7 D). Abdominal sternite VIII with 7 posterior setae; sternites IX–X with 4 setae. On sternites I–VII, P1 asymmetrically absent in all the specimens examined ( Figs. 7 E, F).

Tracheal camerae short and slender ( Fig. 6 J). Antecosta not incised ( Fig. 6 K). Laterostigmata II–V distinct, without reticulation; IV–V small ( Fig. 6 L). Female squama genitalis ( Fig. 6 M) with caput processus broadly bent, bifid at apex; filum processus of medium length; proximolateral and median sclerotizations distinct.

Larva II. Body length 835 μm; head 134 μm long, 103 μm wide; pseudoculus 11 μm long, 10 μm wide, PR = 11.7; foretarsus length 59 μm, claw 16 μm, empodium and seta s 16 μm, TR = 3.7, EU = 1.0, BS = 1.0; length of middle tarsus 29 μm, claw 10 μm; hind tarsus 33 μm, claw 12 μm. Seta P5 on abdominal tergites II–III displaced slightly anteriorly, level with A4 ( Fig. 7 G); those on IV–VII posterior to A4 ( Fig. 7 G).

Diagnosis. The genus Eosentomon contains more than 260 species and is common in most areas of the world. This new species differs from its congeners in the combination of important features such as the bifid head on caput processus of female squama genitalis, pseudoculus with a central globule and longitudinal line, and the absence of foretarsal sensillum c’. The asymmetrical absence of P1 on abdominal sternites I–VII is quite unusual and has been observed in only two species from Yunnan, China: E. belli Yin and E. dian Yin, Xie & Imadaté (Yin et al., 1995) . Aside from the features mentioned above, E. chiangmaiense is distinguished from E. belli in having 2 pairs of anterior setae on tergites V–VII (only A 5 in E. belli ), and from E. dian in having 8 setae on tergite XI (4 setae in E. dian ).

Etymology. The specific name is derived from the name of the province, Chiang Mai, in which the type locality lies.

Figures

FIGURE 6. Eosentomon chiangmaiense sp. nov. A, Head, dorsal view, right half; B, labrum and rostral region; C, maxillary palpus; D, galea; E, mandible; F, pseudoculus; G, interior view of foretarsus; H, exterior view of foretarsus; I, hind tarsus; J, tracheal camerae on thorax III; K, central lobe on abdominal tergite VI; L, laterostigmata II – V; M, female squama genitalis. A – C, G – J, L, M, Holotype, female; D – F, K, paratype, male. Scale bar: 20 μm for A, G – J; 10 μm for B – F, K – M.

FIGURE 7. Eosentomon chiangmaiense sp. nov. A, Thoracic tergite III, right half; B, posterior setae on abdominal tergite VI; C, posterior setae on abdominal tergite VII; D, abdominal tergite VIII, right half; E, abdominal sternites I – IV; F, abdominal sternites V – VIII; G; abdominal tergite II – IV of Larva II, left half. Arrows indicate missing P 1 setae. A – F, Holotype, female; G, Larva II. Scale bar: 20 μm.