Alluaudomyia formosana Okada, 1942

Sarkar, S. & Mazumdar, A., 2017, Description of the female imago and immature stages of Alluaudomyia formosana Okada (Diptera: Ceratopogonidae), Far Eastern Entomologist 339 (339), pp. 16-24 : 17-23

Alluaudomyia formosana Okada, 1942

Figs 1 –30

Alluaudomyia maculipennis var. formosana Okada, 1942: 32 : 317, figs. 5–8 (♀; Taiwan).

2014, coll. S. Sarkar, 6 ♀ (4 pupal exuviae), 3 pupal exuviae, 3 larval exuviae, 11 larvae.

Specimens were also examined under SEM India, the same data, 3 larvae and 3 pupa .

thorax; 4 – wing; 5 – fore leg; 6 – mid leg; 7 – hind leg; 8 – abdomen; 9 – genitalia (scale bar

0.1 mm).

DIAGNOSIS OF FEMALE ADULT ( Figs 1–9 ). Eyes bare, nearly contiguous;

frontovertex ( Fig 1 ) with 8 sensilla chaetica. Mandible with 14–15 teeth of which 7–8 are smaller ( Fig. 2 ). Third palpal segment short with minute sensory pit bearing 3–4 stalked capitate sensilla ( Fig. 2 ). Scutum with 2 lateral longitudinal brown bands with irregular yellow areas; scutellum with 4 large setae ( Fig. 3 ). Wing ( Fig. 4 ) pale brown with yellowish veins, wing length 0.89–0.96 (0.92, n=6); 2 conspicuous large dark spots, one proximal to r-

m cross vein and other at end of costa and 5 small irregular black spots, one near base of M 2,

the others near apices of r 5, m 1, m 2 and cu 1. Hind tibial comb with 7 spines (n=6). Colour pattern of legs in Fig 5–7 . Sermatheca well sclerotized, subspherical ( Fig. 8 ) with short,

narrow, tapering neck, measuring 0.078 –0.084 (0.08, n=6) × 0.058 –0.063 (0.061, n=6). Cerci brown, sinuose ( Fig. 9 ).

head capsule (ventral view); 12 – head capsule (ventrolateral view); 13 – detail of head capsule; 14 – caudal setae; 15 – detail caudal setae (scale bar for all figs 0.1mm except fig

13, scale bar 0.05 mm).

2.79–3.20 (3.01, n=5). Exuviae yellow. Head capsule (Figs 11, 12, 23–25) yellow to brown,

oval, with well developed frontal suture; head capsule length (HL) 0.204 –0.244 (0.224, n=8),

head capsule width ( HW) 0.144 –0.163 (0.151, n=8); head capsule ratio (HR) 1.42–1.56

(1.49, n=8); eyes with 2 separated spots; head setae simple, short to elongate but ‘s’, ‘u’, ‘x’

and ‘o’ setae bifurcated and branched, chaetotaxy shown in Figs. 12, 23–25. AN (Fig 25)

small, antennal length (AL) 0.013 (n=6). CO (Figs 11, 23) and subgenal band dark; subgenal width ( SGW) 0.081 –0.098 (0.088, n=8) ; subgenal ratio (SGR) 1.67–1.79 (1.71, n=8).

tory organ (1 and 2 indicates two lateral pores); 18 – dorsal sensilla; 19 – fourth abdominal segment (ventral view); 20 – fourth abdominal segment (dorsal view); 21 – first abdominal segment; 22 – ocular sensilla (scale bar 0.1 mm).

Labrum 0.8 times longer than wide; palatum (Figs 11, 23, 24) with three pairs of anterior ss,

two pair of posterior st and one pair of SCa; MS (Fig. 11) well developed, elongated, club shaped; SC (Fig. 11) well developed with six stout, lanceolate teeth; HY (Figs 23, 24) round,

sclerotized and smooth. MD (Figs 11–13, 24) base broadened, minute seta on the basal portion near hypocondyle, apical tooth gently curved, pointed, sub median tooth small, blunt.

Length of mandible ( MDL) 0.037 –0.046 (0.040, n=8), width ( MDW) 0.012 (n=8). EP (Figs

11–13) with three combs: DC sclerites relatively wide with 14 moderate size, sub-equal,

lanceolate teeth directed posteriorly, 7 on each half, a large median tooth; comb 2 with a large tooth-like process, comb 3 absent, comb 4 or VC with 10 stout, short teeth; each lateral arm with a fringe with 5–6 minute teeth like projection; lateral arm width ( LAW) 0.042 –

0.053 (0.049, n=8), dorsal comb width ( DCW) 0.017 –0.029 (0.023, n=8). HP (Figs. 11–13)

slender, heavily sclerotised, posterior end of each arm irregular without fringe. Thoracic pigmentation brown (Fig. 10). Caudal segment (Figs. 14, 15) slender, chaetotaxy as in Figs.

14 and 15; caudal segment length ( CSL) 0.319 –0.390 (0.341, n=8), caudal segment width

(CSW) 0.065 –0.081 (0.073, n=8); caudal segment ratio (CSR) 4.42–4.75 (4.53, n=8).

DESCRIPTION OF FEMALE PUPA (Figs 16–22, 26–30). Total length 1.88–2.04 (1.97,

n=7). Exuvium light brown, cephalothorax brown, length 0.83 (0.80–0.84, n=7) and width

0.56–0.60 (0.58, n=7). RO light brown, short (Figs 17, 26–27), length 0.154 –0.162 (0.158,

n=7) and width 0.046 (n=7); apex expanded, brown, arranged in double rows of 14–15 pairs pores; 2 lateral pores near the base; outer surface covered with spicules. P short (Figs 17, 26,

27), length 0.025 (n=7), yellowish, smooth, base membranous with several folds; tracheal tube prominent, slightly curved; P/RO 0.154 –0.162 (0.158, n=7). Dorsal apotome (Figs. 16, 26)

yellowish brown, disc slightly wider than length, anterior end rounded, central region with pair of sub lateral, more or less circular raised areas. Surface with small knob like projections around a median portion and arranged in a single row of larger projections lying behind lateral angles. Surface of posterior margin with numerous spicules and a few tubercles between the raised areas; posterior margin slightly concave. Dorsal apotome length ( DAL) 0.129 –

0.133 (0.131, n=7), dorsal apotome width ( DAW) 0.154 –0.158 (0.155, n=7), DAW /DAL

1.157 –1.224 (1.19, n=7). Two dorsal apotomal sensilla (Fig. 16): DA-1-H short, stout located on rounded small tubercle, DA-2-H campaniform sensillum, located at the base of tubercle;

clypeal/labral absent; four ocular sensilla (Fig. 22): O-1-H thin, short, at the base of palpus,

O-3-H thin, long, seta, with 2 campaniform sensilla (O-2-H, O-4-H); dorsolateral cephalic sclerite sensilla with one stout small seta (DL-1-H) from well developed base and one campaniform sensillum (DL-2-H). Five dorsal setae clearly distinguished (Figs 18, 26, 28):

D-1-T, D-2-T and D-5-T with small, stout seta; D-4-T with long, thin seta, D-3-T campaniform sensillum; one supra alar (SA-2-T) campaniform sensillum; anteromedials (Figs 17,

27) two setae: one short, stout (AM-2-T) and other long, thin (AM-1-T); anterolaterals (Fig.

27) three setae: one short and blunt (AL-3-T), one medium sized (AL-2-T) and one long, thin

(AL-1-T). Metathorax (Fig. 21) completely divided with rounded ends, metathoracic- 1 seta

(M-1-T), and 2 campaniform sensilla (M-2-T, M-3-T). Abdominal tubercles short, with single, pointed or rounded apex; abdominal segment 1 (Fig. 21) with 8 setae including 3

lateral setae, 1 campaniform sensillum, D-2-I, D-3-I closely associated, D-7-I absent, D-4-I campaniform sensillum. Segment 4 (Figs. 19, 20, 29): D-2-IV short seta on small, stout and simple tubercle, D-3-IV long, thin bifurcated seta on stout, small tubercle; D-4-IV campaniform sensillum, D-5-IV short, stout seta on small tubercle, D-7-IV sensillum absent, D-8-IV medium sized, stout seta, D-9-IV long and thin seta; L-1-IV short seta on pointed tubercle; L-2-IV, L-

3-IV and L-4-IV short setae on pointed tubercles; V-5-IV short, stout seta, V-6-IV long, thin seta and V-7-IV short, thin seta, all on small tubercles. Segment 9 (Fig. 30) broad, posteriorly directed spinules covering 2–3 rows anterodorsally, spinules scattered over dorsal surface,

tapering to pointed apex. Caudal segment length ( CSL) 0.141 –0.145 (0.142, n=7),

(26–30). 23 – head capsule chaetotaxy (ventral view); 24 – head capsule (frontal view); 25 –

head capsule chaetotaxy (lateral view); 26 – Dorsal apotome & cephalothorax; 27 – Cephalo-

thoracic chaetotaxy; 28 – Dorsal sensilla; 29 – Chaetotaxy of abdominal segment 4; 30 –

Segment 9.

caudal segment width ( CSW) 0.116 –0.121 (0.118, n=7), TP 0.054 –0.062 (0.057, n=7) short ,

with several spinules and sharp end with D-5-IX campaniform sensillum on base.

DISTRIBUTION. Taiwan, Malaysia, Thailand, and India (new record).

BIONOMICS. Larvae were collected from floating algae by scoop sampler and also from algal substances associated with rotten logs, stems from a margin of permanent pond coexisting with Dasyhelea ornaticornis Kieffer and Alluaudomyia xanthocoma Kieffer. The physiochemical characteristics of pond water at the time of collection were as follows: water temperature 32.8ºC, pH 8.47, TDS 182 ppm, salinity 139 ppm and conductivity 257 μS/m.

Due to minute size and rapid movement the larvae it was difficult to separate from algal mat.

Possession of larvae with 4 pairs of long setae at caudal segment indicates that they are good swimmer and heavy pigmentation of thoracic region helps in better camouflaging and are adapted to avoid and escape from predator (Elson-Harris & Kettle, 1985). The larva performs very fast serpentine movement on the surface film, a unique habit observed by Thomsen

(1937) and Grogan & Messersmith (1976) for some Nearctic species and Elson-Harris &

Kettle (1985) for some Australian species.

Figures

Figs. 1–9. Alluaudomyia formosana, adult female. 1 – frontovertex; 2 – mouthparts; 3 –