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, with 1

minute bristle in apical part. Left surstylus with upper lobe

(Fig. 23) divided; lower part elongate, lacking surstylar comb,

upper part moderately large, subglobular, with 1 short bristle.

Right surstylus (Fig. 24) large, rather elongate oval, lacking

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

with 1 long bristle in apical part. Right cercus consisting of

two lobes, lacking spines; left lobe short, broad, with several

bristles basally; right lobe hardly prominent, rounded. Phallus

short.

Female. In most respects identical to male. Palpus brownish

yellow. 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. – This species is dedicated to Dr. La-aw

Ampornpan from Srinakharinwirot University who stimulated

our studies of the Thai fauna.

Phylogenetic relationships. – The relationships of this species

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. crassinervis,  S.

nhamyaaw, and S. taksin.

Distribution and seasonal occurrence. – Thailand. Known

from two localities, respectively in Central and Northeast

Thailand. Records from the beginning of September to the

beginning of October.

Stilpon nhamyaaw, new species

(Figs. 25-29)

Material examined. – Holotype - male, THAILAND: Ranong

province, Ranong, rain forest, along stream, sample n

°

 96028, 6

Apr.1996, coll. P. Grootaert (coll. RBINS).

Paratypes – 5 males, 2 females, same data as in holotype

(RBINS).

Diagnosis. – Species with yellow thorax, resembles S. laawae

differing from its by yellow fore tibia and tarsomere 1, wing

Figs. 20-24. Stilpon laawae, new species, male. 20, mid leg, anterior view, 21, wing, dorsal view, 22, hypopygium, ventral view, 23, upper

lobe of left surstylus, dorsal view, 24, right surstylus, dorsal view. Scale bar: 0.1 mm.

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THE RAFFLES BULLETIN OF ZOOLOGY 2004

pattern consisting of two distinct brownish spots. Male:

abdominal segment 8 with 2 very long bristles, left cercus

with 3 very long spines in middle part.

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

minute ocellars and hardly prominent inner verticals. Antenna

yellow. Postpedicel nearly 2.0 times longer than wide. Style

about 5 times longer than postpedicel. Palpus pale.

Thorax almost entirely yellow. Scutum with 2 indistinct

brownish spots near postalar calli, entirely tomentose.

Postpronotal bristle hardly prominent. Dorsocentrals in

multiple rows, complete posteriorly. Acrostichals 2-serial,

complete posteriorly.

Legs with colour pattern: hind femur brownish yellow in

apical 3/4, otherwise legs yellow. Mid coxa with 2 brown

bristles on outer side. Hind trochanter lacking spinules. Mid

femur (Fig. 25) slender, with 4 long yellow bristles in basal

1/2. Hind femur (viewed laterally) more or less evenly

thickened, with row of anterodorsal bristles (5-6 subapical

longer) and some prominent anterior and dorsal bristles in

apical part. Fore tibia with ordinary setulae. Mid tibia lacking

ventral spinules. Hind tibia with some longer ventral setulae,

posterior apical comb unmodified.

Wing normally developed, covered with uniform

microtrichia; with pattern consisting of 2 brownish, large,

elongate oval spots separated more or less distinctly by pale

basal half of vein M; remainder parts finely infuscate. Costal

vein with short setulae along anterior margin. Vein R2+3

about 1.5 times longer than Rs. Distance between apices of

R2+3 and R4+5 about 1.5 times longer than distance between

apices of R1 and R2+3. R4+5 and M almost parallel and

evenly arcuate in apical part. Halter with elongate, contrast

black knob and pale stem.

Abdomen lacking gland-like structures. Segments 1-2 largely

pale yellow, remainder segments yellowish brown and

stronger sclerotized. Segment 8 with 2 very long and several

shorter bristles.

Hypopygium (Fig. 26) brown, small. Hypandrium with 2 long

bristles in apical part. Epandrium completely divided. Left

epandrial lamella small, fused to hypandrium, with 2 minute

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

27) divided; lower part elongate, lacking surstylar comb,

upper part subglobular, with 1 short bristle. Right surstylus

(Fig. 29) fairly large, somewhat broadened toward apex, with

more or less rounded upper margin. Left cercus (Fig. 28)

unbranched, hardly prominent, with 3 very long spines. Right

cercus unbranched, hardly prominent, with several marginal

bristles of different length. 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

Figs. 25-29. Stilpon nhamyaaw, new species, male. 25, mid leg, anterior view, 26, hypopygium, ventral view, 27, upper lobe of left surstylus,

dorsal view, 28, left cercus and subepandrial sclerite, right lateral view, 29, right surstylus, dorsal view. Scale bar: 0.1 mm.

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