Chen Ng(Pg61-69)

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Shamshev & Grootaert: A review of the genus Stilpon from the Oriental region

2 long bristles in apical part. Epandrium completely divided.

Left epandrial lamella small, fused to hypandrium, lacking

bristles in apical part. Left surstylus with upper lobe (Fig.

38) divided; lower part slender, lacking surstylar comb, upper

part subglobular, with 1 short bristle. Right surstylus (Fig.

39) fairly large, rather elongate oval, with rounded apex,

lacking spines. Left cercus unbranched, slender, short, lacking

spines, with several bristles of different length in basal part.

Right cercus consisting of two lobes, lacking spines; right

lobe hardly prominent, with several marginal bristles of

different length; left lobe short, broad, rounded at apex.

Phallus short.

Female. In most respects identical to male. Terminalia

shortened. Segment 8 normally sclerotized. Proximal margin

of sternite 8 without 2 anteriorly directed rods. Apex of

sternite 8 hinged and partially separated from base. Sternite

10 uniformly sclerotized, not fused with ventroapical margin

of tergite 8. Cercus elongate oval, brownish yellow, clothed

in setulae of different length.

Measurements. – Body length 1.4-1.7 mm, wing length 0.9-

1.2 mm.

Etymology. – “Taksin” (south in Thai) refers to south of

Thailand where this species was found.

Phylogenetic relationships. – The relationships of S. taksin

are unresolved beyond inclusion within the S.  seeluang

species group. However, the presence of 2 very long bristles

on the segment 8 of the male abdomen, the general structure

of the male terminalia and, especially, the greatly reduced

cerci suggest this species is allied with S. laawae,  S.

crassinervis, and S. nhamyaaw.

Distribution and seasonal occurrence. – Thailand. Only

known from one locality in South Thailand. The record is

from October (end of rainy season in South Thailand).

The S. divergens species group

Cumming & Cooper (1992) have recognised this group to

include a single species known just from the Oriental region

only. Additionally, they noted also some undescribed species

from Africa and Japan. We have added to this group another

6 species described below. Members of the S. divergens

species group are characterised by an entirely black thorax

(except S. malayensis) and tomentose scutum, complete rows

of acrostichal setulae, presence of gland-like structures on

the male abdomen (unclear in S. divergens), undivided upper

lobe of left surstylus, markedly developed surstylar comb,

bilobed right cercus, a long ventral bristle on left cercus, setose

left cercus, long bristles in apical part of left epandrial lamella,

elongate hair-like phallus, elongate female terminalia and

sternite 8 of the female terminalia with upper apex not

partially separated from base.

Stilpon khorngkeun, new species

(Figs. 40-44)

Material examined. – Holotype - male, THAILAND: Loei

province, Na Haeo, FIRS, Malaise trap in bamboo forest at Na Haeo

FIRS, 1 male, 7-14 May.2000, coll. P. Grootaert (SWU).

Paratypes – Same data as in holotype: 1 male, 17-24 Sep.1999;

1 male, 24-30 Apr.2000; 1 male, 13-20 May.2001; 1 male,

29 May.-4 Jun.2001; 1 male, 7-14 Jul.2001, coll. Verapong

Figs. 36-39. Stilpon taksin, new species, male. 36, mid leg, anterior view, 37, hypopygium, ventral view, 38, upper lobe of left surstylus,

dorsal view, 39, right surstylus, dorsal view. Scale bar: 0.1 mm.

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329

THE RAFFLES BULLETIN OF ZOOLOGY 2004

Kiatsoonthorn & P. Grootaert; 2 males, Na Haeo FIRS,

Malaise trap n

°

 1 in bamboo wood, 25 May.2003 (leg. P.

Grootaert); 3 males, Na Haeo FIRS, base of waterfall, sample

n

°

 23029, 16 May.2003 (leg. P. Grootaert). (in coll. SWU,

RBINS & ZRC).

Diagnosis. – Species with black thorax, differing from other

species from the Oriental region by R4+5 strongly curved in

apical part and by brown hind tarsomere 1.

Description. – Male. Head black in ground-colour, with

minute anterior ocellars, short (half as long as inner verticals)

posterior ocellars and long inner verticals. Antenna yellow.

Postpedicel nearly 2.0 times longer than wide. Style about 5

times longer than postpedicel. Palpus brownish yellow.

Thorax brown. Scutum entirely tomentose. Postpronotal

bristle long, inclinate. Dorsocentrals in multiple rows,

complete posteriorly. Acrostichals 2-serial, complete

posteriorly.

Legs with colour pattern: hind femur brownish yellow in

apical 2/3, tarsomere 5 of all legs and hind tarsomere 1 brown;

otherwise legs yellow. Hind trochanter lacking spinules. Mid

femur (Fig. 40) slender, with long pale ventral bristles in

extreme base and 2 ventral yellowish spines nearer to middle.

Hind femur (viewed laterally) evenly thickened toward

middle, with short anterodorsal bristles (3 subapicals longer),

lacking prominent dorsal bristles near base but with prominent

dorsal bristles in apical part. Fore tibia with short, hardly

prominent, brownish, posterodorsal bristle at apex, lacking

prominent ventral bristles. Mid tibia considerably shorter than

mid femur, with rows of ventral spinules and 1 longer

subapical spinule. Hind tibia unmodified.

Wing (Fig.  41) normally developed, covered with uniform

microtrichia, finely infuscate. Costal vein with ordinary short

setulae on anterior margin. Veins R2+3 and R4+5 thickened,

darker than other veins (especially R4+5). Vein R2+3 about

3 times longer than Rs. Distance between apices of R2+3

and R4+5 nearly 1.5 times shorter than distance between

apices of R1 and R2+3. R4+5 strongly curved at apex. R4+5

and M divergent in apical part. Vein CuA1 not quite reaching

wing margin. Halter with brown elongate knob (one specimen

had a very dark knob) and pale stem.

Abdomen largely yellowish brown, bearing mostly scattered

dark setulae which are longer on pregenital segments, with

all tergites (except segment 8) of subequal in length, tergites

1-2 unmodified. Narrow gland-like structures present between

tergites 4-3 and 3-2.

Hypopygium (Fig. 42) brown. Hypandrium with 2 strong

bristles in apical part. Epandrium completely divided. Left

epandrial lamella small, fused to hypandrium, with 2

moderately long bristles in apical part. Left surstylus with

Figs. 40-44. Stilpon khorngkeun, new species, male. 40, mid leg, anterior view, 41, wing, dorsal view, 42, hypopygium, ventral view, 43,

upper lobe of left surstylus, dorsal view, 44, right surstylus, dorsal view. Scale bar: 0.1 mm.

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