Head
The head capsule (Fig. 3A, B) is oval in dorsal view, with length 1.59–1.62 mm, width 1.01–1.05 mm (n = 15). The posterior part of head is held in place by the cervical membrane at the articulatory fold. Most parts of the head are dark brown or black, except for the oval less pigmented parts on lateral sides. The exposed anterior parts of the head are strongly sclerotized, and the internalised posterior parts (externolateraliae and internolateralia) are less sclerotized than the exposed parts. The externolateraliae have numerous growth lines near the posterior margins. A pair of sword-shaped incisions reach nearly posterior 1/3 of the head. Anteriorly each incision is continuous with a deep grove that extends nearly 2/3 of the head. The paired incisions separate lateral genal regions (externolateraliae) from the dorsal fragment (internolateralia) of the head (Cook, 1949; Oosterbroek & Theowald, 1991). Externolateraliae are widely separated on the ventral surface by a huge incision. Both genal regions are strongly sclerotized at edges. The eye spot is immediately close to each mandibular articulation.
The clypeus is generally pale with a pair of basal darkened areas. Three pairs of setae are present: a pair of anterior setae are long and close to the base of the antennae; a second pair are of medium length; and the other pair are very short and posterior to the medium-length setae (Fig. 4A, B).
The antenna has only one segment, brownish and cylindrical, slightly curved inward. It is nearly two and a half as long as the basal width. A large cone-shaped and six peg-like sensilla are located on the membranous sensory area at tip of the antenna (Fig. 4A, B). The basal half of antenna bears a dorso-mesal pit-like sensillum. Trapeziform labrum is separated from the clypeus region by a clypeolabral suture (Fig. 4A, B). The labrum consists of a membranous part in the middle and a pair of sclerotized lobes on each side. Each sclerotized lobe has two groups of microtrichia along the lateral edge and three long setae on the anterior part. The anterior margin of the labrum has dense hairs in rows (Fig. 4A–D). A pair of long setae raised from a shorter hair cluster base to the medio-anterior margin (Fig. 4C).
The anterior part of the epipharynx is densely covered with posteriorly directed flat hairs (Fig. 5A–C). The lateral part of the epipharynx is reinforced by a sclerotized, slightly curved tormae and is covered by densely hair (Fig. 5A). A pair of rounded cushiony lobes are present on the central part of the epipharynx. Each cushiony lobe is partly covered with a group of hairs (Fig. 5B, D). Two pairs of teeth arrange in a curved row just behind the two cushiony lobes. Each tooth has a pair of peg-like sensilla on the tip (Fig. 5B, D).
The mandibles are strongly sclerotized and slightly curved inwards. Each mandible is only one-segmented and operates in the horizontal plane (Fig. 6). Four teeth are present on each mandible (Fig. 6A, B, D, E), including the largest one pointed anteriorly, a subapical one on dorsal edge, and two additional (a sharp and a blunt) ones on ventral edge. Each mandible bears a triangular lacinia mobilis on the mesal surface. It is sclerotized, fan-shaped, and bordered by a fringe of hairs (Fig. 6C, F). On the mandible, two long setae are present on posterolateral area, and a sensory pit posterodorsally (Fig. 6A, B).
Each maxilla consists of a cardo, a stipes, a maxillary palp, a galea and a lacinia (Fig. 7A–D). The cardo is wedge-shaped, brown to black. A pair of setae are present on the anterior margin of the cardo, almost equal in length (Fig. 7A, C). The stipes have three sclerites. The inner sclerite extends from ventral surface of the maxilla around the inner margin onto the dorsal surface, while the outer sclerite extends around the outer margin (Fig. 7A, B). The median sclerite is somewhat triangular, extends from the inner sclerite to the distal end of the cardo (Fig. 7A). The one-segmented maxillary palp is situated on the membranous palpifer. The tip of the maxillary palp bears a membranous sensory area, and several small peg-like sensilla are inserted apically (Fig. 7D). The galea has a cone-shaped sensillum dorsally, and a thin seta ventrally. The lacinia has a strong seta and a tuft of long paddle-shaped appendages. Almost the whole dorsal surface of the stipes, the galea and the lacinia are covered with groups of dense hairs (Fig. 7D).
The prementum is almost entirely covered by the hypostomium. It bears five round blunt teeth at the anterior edge. The middle three teeth are similar in size, and the pair of the most lateral teeth are smaller. The prementum is strongly sclerotized, except for the basal round membranous area, which is covered with dense bristles on ventral surface, with a pair of labial palps dorsally (Fig. 8A, D).
The base of hypopharynx is fused with the prementum (prelabio-hypopharyngeal-complex) ventrally. The hypopharynx is membranous and spoon-shaped, supported below by a pair of U-shaped hypopharyngeal suspensors (Fig. 8A, B, E). The disc of the hypopharynx is broadly covered with squamaceous hairs, while the rest part is covered with dense pubescence (Fig. 8B, E).
The toothed hypostomium (Fig. 8C, F) is a separate plate-like sclerite. It is strongly sclerotized and fused with the genae complex. The anterior margin equips with seven sharped teeth. The apical tooth is the biggest and candle-shaped; the middle two pairs of teeth are similar in size and smaller; the most lateral pair are the smallest. The dorsal base of the hypostomium has a group of fine hairs. The posterior part of the hypostomium is divided along the midline by a membranous area. A pair of tiny knee-shaped sclerites are present on the posterior edge (Fig. 3B).
Thorax and abdomen
The thorax and abdomen segments are generally pale yellow, covered with brown microscopic hairs. The second and third thoracic segments and the first abdominal segment are wider than each length. The first thoracic segment and the 2nd–8th abdominal segments are longer than each width (Fig. 2A–C). On dorsal surface, the microscopic hairs on the third thoracic segment and the first and the eighth abdominal segments are longer than those on the other segments (Fig. 2A–C). The lateral surface has several round glabrous patches (Fig. 9H, J). The setae are black on base and brown on apex. They are arranged in roughly similar way on the first to seventh abdominal segments, except for the lateral seta L4 (Fig. 9C, D). Ventral setae V4, V5 and V3 are long, three more times as long as V2. Seta V1 is very short, only half the length as V2. Setae V4 and V5 are very close to each other, and they are far from the V1–3 (Fig. 9A). Dorsal setae D1–3 are long; D4 and D6 are short; D5 is vestigial or absent. Setae D1–4 are basically at the same height, and D6 is directly above D4. Setae D2 and D3 are very close to each other, and they are fairly far from D1 (Fig. 9B). Lateral setae L1 and L4 are long; L2 and L3 are very short. On the first abdominal segment, seta L4 is fairly far from the group of setae L1–3, but it is close to the other three setae on the 2–7 abdominal segments (Fig. 9C, D).
Dorsal and lateral spiracular lobes are both nearly conical; each lobe is fleshy and glabrous. The paired small dorsal lobes are approximately as long as width. They are so close to each other that the distance between is much less than the width of each lobe. A brown elongate sclerotized pattern is present just below the base of each dorsal lobe. The lateral lobe is closer to the dorsal lobe than to the ventral lobe, nearly 1.5 times as long as the dorsal lobe. A tiny spot or stripe is present at the base of the lateral lobe. Ventral lobe is short, broad triangular, about half as long as wide. The paired ventral lobes are directed outward. A transverse trapeziform sclerotized area is present on the base of upper surface of each ventral lobe. The spiracles are black, round and strongly sclerotized. The distance between the two spiracles is approximately equal to the spiracular diameter. A small black round pit is located at the central area between the two spiracles (Fig. 10A–D).
The anal field is nearly inverted trapezoid in shape. Two pairs of short, round, fleshy and glabrous anal papillae are produced around anus. The lateral papillae are relatively longer than the ventral papillae. The papillae expand laterally to make the anal field slightly broader than the spiracular disc (Fig. 10A–C).