Aspistomella duo Kovac, Kameneva & V. Korneyev 2024, sp. nov.
Creators: name: Kovac, Damir
name: Kameneva, Elena P.
name: Korneyev, Severyn V.
name: Araújo, Alexandre Santos
name: Savaris, Marcoandre
name: Smit, John T.
name: Schneider, Alexander
name: Schreiber, Robert
name: Korneyev, Valery A.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Ulidiidae
Aspistomella
Aspistomella duo

description: Aspistomella duo Kovac, Kameneva & V. Korneyev, sp. nov.
urn:lsid:zoobank.org:act: 69AD65D5-477E-4DA8-AC63-6050B37FFEFF
Figs 1 B, 5 C, 7 A, 9 A, G, 14–21
Material. Type. Holotype ♂: “ Bolivia: Buena Vista, near Santa Cruz [El Cairo, 17.5009S, 63.6743W]; on upright bamboo culm (Guadua chacoensis, last year); 29.i.2011; Bol 91/11 leg. D. Kovac ” (SMF). Paratypes: 2♂, 1♀ (1♂, 1♀ dissected); Bolivia: same data as for holotype (D. Kovac leg.) (SIZK); 2♀, same data as for holotype (D. Kovac leg.); larva in bamboo internode (Guadua chacoensis, last year), emerging on 8.ii.2011, Bol 156/111, (leg. D. Kovac) (SMF).
Non-type. Bolivia: Buena Vista, near Santa Cruz (El Cairo); [17.4734S, 63.6922W], 1.xii.2007, Bol.76.07; 1 ♂ (alcohol collection) (D. Kovac leg.) (SMF); 1.12.2007, Bol.77.07, 5♂; (alcohol collection) (SMF); same label, 1♂, (SEM stub) (SMF); same label, 1♂ (SIZK).
Larvae. Bolivia: Buena Vista, 6.ii.2011, BolZ32/11, 6 larvae (D. Kovac leg.) (SMF).
Diagnosis. Aspistomella duo is similar to other species of the genus having a very short pterostigma, shorter than the width of the costal cell (Fig. 5 C), but differs from them in details of the wing pattern: apical quarter of cell r 4+5 completely dark (in A. heteroptera, A. enderleini, A. lobioptera, A. lunata, A. steyskali, crossed by crescent hyaline incision); Aspistomella duo is similar to A. tres in having wing apex without hyaline incisions crossing cell r 4+5 and vein R 1 dorsoapically setulose, but differs from it in having cell dm between crossveins r-m and dm-m completely dark and a conspicuously narrower wing.
Description. Adult. Male. Head (Figs 14 B–D) ratio (length: height: width) = 1: 1.4: 1.75, frons, parafacial and gena reddish or yellowish brown, except anterior part of frons. Lunule and face between antennae yellow. Occiput mostly black, at least in dorso-lateral part. Frons (Fig. 14 D, C, 15 A) 1.15× longer than wide, with shiny, partly brown or black ocellar triangle and brown vertical plates; orbits silver-white microtrichose; parafacial narrow, 0.2–0.3× broader than postpedicel, white microtrichose. Frontal setulae short, moderately strong, black, proclinate and partly inclined, forming three irregular rows of 2–6 setulae on each side, anteriormost setulae longer than others and as long as outer vertical seta; 1 very long orbital seta, 1.3× longer than ocellar seta, 0.75× longer than inner vertical seta and 2.5× longer than outer vertical seta; postocellar seta long, 0.4× longer than inner vertical seta; outer vertical seta short, 0.3–0.4× longer than inner vertical seta and 2–3× longer than postocular setae forming one row, allied by 8–9 dorsal and 13–19 ventral occipital setae. Lunule very narrow, indistinct, orange. Eye 1.5–1.7× higher than long. Face (above suture) 0.5× higher than wide at transverse fold, yellow to brownish yellow, densely white microtrichose; epistome reddish brown to black (medially), sparsely white microtrichose, with metallic greenish or golden sheen, strongly produced anteriorly and separated from upper part of face by deep suture. Clypeus yellow, densely white microtrichose, matt, 0.5–0.6× higher than epistome. Gena brownish yellow, with long genal seta and 5–6 additional setae anterior to it, 0.6–0.8× longer than genal seta. Occiput black, except postgena brownish-yellow, with yellowish to cyan metallic sheen, moderately densely covered with greyish microtrichia partly hiding underlying cuticle; ventral part of occiput (postgena) with 4–6 setae almost as long as genal seta. Antenna brownish yellow; scape and pedicel with black setulae; postpedicel brown, often blackish apically, whitish microtrichose, 2–2.2× longer than wide, apically rounded; arista black except yellow at base, almost bare. Mouthparts black, prementum black, shiny. Palp yellow, narrowly crescent-shaped, apically rounded, with 10–12 strong black setulae, of which 2–3 subapical setulae 1.5–2× longer than other setulae.
Thorax (Figs 14 E, 16 A) brown to black, with bluish sheen and sparse white microtrichia not obscuring underlying cuticle. Mesonotal scutum 1.3× longer than wide; presutural area with large black patch and brown margin, including postpronotal lobes and notopleuron; 3 pairs of black vittae: short submedially, reaching posteriorly only to level of postsutural supra-alar seta, intra-alar and supra-alar vittae fused anteriorly at transverse fold and reaching level of intra-alar setae and yellow to dark brown prescutellar area; black setulose, with 10–14 rows of setulae between rows of dorsocentral setulae; acrostichal prescutellar setae present (in 3 of 6 specimens examined), absent (in 2 of 6 specimens examined), or present on one side only (in 1 specimen examined); prescutellar area medially setulose and without setulae around dorsocentral setae. Scutellum dorsally very slightly convex, orange to reddish brown, matt, sparsely microtrichose, without setulae, laterally sometimes with inconspicuous silvery sheen. Subscutellum subshining, dark brown. Mediotergite shiny black, sparsely microtrichose. Other setae as described for the genus. All the setae and setulae black.
Wing (Fig. 5 С) 6.1–7.7 mm (♂), 5.7–7 mm (♀) long, 2.9–3.5× longer than wide; basicostal cell hyaline; costal cell lobed, 4× longer than wide, brown in basal and apical quarters of length, with costa conspicuously curved posteriorly and covered with slightly longer setulae before apex of vein Sc; pterostigma entirely brown, narrowly triangular, 0.4–0.5× longer than wide, vein R 1 with 3–4 setulae dorsally, ending slightly proximal of crossvein dm-m level in both sexes (Fig. 14 G); vein R 2+3 almost straight, subparallel to costa to very apex. Crossvein r-m slightly distal to center of cell dm in both sexes. Cell r 4+5 7–8× longer than wide, apically narrowed. Cell m 1 narrowly triangular; ultimate section of M 1 4–5× longer than crossvein dm-m and 2–2.5× longer than penultimate section. Vein CuA Z-shaped, cell cua with moderately short posteroapical lobe along vein CuP. Wing pattern with short subbasal crossband from humeral vein to base of cell cua and large dark brown, Z- or 2-shaped mark widely from apical lobe of costal cell almost to base of cell dm and longitudinal fold of cell m 4, and 2 wide triangular incisions from cell r 1 into cell dm distally from crossvein r-m and from base of cell m 1 into cell r 4+5. Calypters white, with white ciliae. Halter brown with black or brown knob (Figs 14 H, 16 G, H).
Legs (Figs 14 A, F, 16 I–O) with yellow or brownish-yellow coxae and trochanters, femora entirely yellow to entirely brown; tibiae and tarsi either brownish yellow or brown, in 2 specimens contrasting with yellow femora, black setose and setulose, without conspicuous microtrichia or metallic sheen in examined specimens. Fore femur with 2 rows of posterodorsal and posterior setae, and 3–4 preapical posteroventral setae, all slightly shorter than femur width. Mid femur anteriorly and posteriorly with short setulae, but without long erect setae; mid tibia ventrally with two subequal spur-like setae 2–2.5× longer than tibia width (Fig. 16 K). Tarsi as on Figs 17 J–O.
Abdomen moderately elongate (Fig. 16 C) brown to completely black, syntergite 1+2 often brownish-yellow; tergites finely sparsely microtrichose, with faint cyan metallic sheen, except tergite 5 of ♂ brown or black without metallic sheen; setulae and setae black. Male tergites 3, 4 and 5 of subequal length. Female tergite 6 short, hidden underneath tergite 5; sternite 6 transverse; oviscape as long as tergites 4–6 combined.
Postabdomen. Cerci short setulose, dorso-ventrally flattened and broadly fused, posteriorly very shallowly bilobate (Figs 17 D, E). Epandrium short setulose, with setulae 3–6 × narrower than base of surstylus (Figs 17 A, B). Each surstylus basally broad, gradually curved mesally, with a row of five shortened setulae on its mesal surface, two of which conspicuously thickened, but not strongly sclerotised (Fig. 17 A). Pregonites symmetrical, slightly lobed, with 5 setulae ventro-mesally, conspicuously anterior to postgonites (Figs 17 F, G, I). Postgonites rounded, with 5–6 small trichoid sensilla (Figs 17 F, H, I). Phallus basally short microtrichose, apically with numerous lamellar cuticular sclerotisation, about 3.5 mm long; in rest, coiled on right side of abdomen (Fig. 17 K).
Female: all taeniae 0.66× longer than eversible membrane (Fig. 18 B); aculeus not flattened (Fig. 18 C), with long setulose ovoid cercal unit and (Fig. 18 C), 1.9 mm long; 2 subglobose spermathecae (Fig. 18 A, E).
Third instar larva. General structure. Mature larva whitish, muscidiform, length 7.5–11.2 mm (median: 8.45 mm; n = 8), width 1.8–2.5 mm (median: 2.4 mm; n = 8), anteriorly conical, posteriorly rounded, broadest at caudal segment (or sometimes posterior end of abdominal segment VII), surface largely smooth except of spinules of the locomotory creeping welts on ventral abdominal segments I–VII and caudal segment, anterior spiracles fan-shaped, roundish spiracular discs dark, bearing three spiracular openings radiating in a sinuous line out from ecdysial scar.
Pseudocephalon (Figs 19 A–F) flat ventrally, rounded dorsally, deep incision between cephalic lobes, ventral half of incision connected to oral cavity (Fig. 19 A). Antenna three-segmented, located dorso-laterally on cephalic lobe near head apex; basal segment broad and round, second segment slightly conical when extended and surface covered by two finger-like extensions of the epidermis, apical segment conical with rounded apex (often collapsed in SEM specimens) (Figs 19 A–C, E). Maxillary sense organs located on ventral side of cephalic lobes, maxillary palpus contains three papillary sensilla and two knob sensilla enclosed by an incomplete cuticular fold, dorsolateral group of sensilla contains two papillary sensilla (Fig. 19 F).
Mandibles completely smooth with flattened apices, separated from each other by two median oral lobes (Fig. 19 C). Facial mask occupies flat ventral area of pseudocephalon as well as semicircular lateral area (Figs 19 A, B). Central oral ridges adjacent to oral cavity wide, narrowing laterally, narrow part often interrupted by a single narrow gap. Additional short, narrow lateral oral ridges present in lateral semicircular area, protruding between the longer central oral ridges (Figs 19 A, B). Oral ridges regularly dentate, teeth densely stacked, with rounded tips. Twenty-eight central oral ridges adjacent to oral cavity, identical on both sides of the body (n = 2 larvae). Caudal region of oral cavity closed by labial lobe bearing two rounded indentations (labial organ, Fig. 19 D). Four pairs of pseudocephalic cuticular pit-sensilla, one pair between the antennae, one pair laterally on the cephalic lobes, one pair in the latero-caudal part of the oral ridges and one pair flanking the labial lobe (Figs 19 C, D).
Cephalopharyngeal skeleton (Fig. 7 A) total length = 1.6–1.7 mm (n = 2). Base of mouthhooks dark brown with elongate, light brown window, long, thin, curved apical tooth lighter brown than base of mouthhook, indentation between tips of apical tooth and ventral apodeme 0.57–0.60× as deep as wide; neck well developed; preapical tooth absent; ventral apodeme large, ventrally oriented; dorsal apodeme oriented posterodorsally. Small dental sclerites visible. Hypopharyngeal sclerite 4.0–4.5× longer than high, anterior part dark brown, posterior part light brown. Hypopharyngeal bridge slightly anterior to the mid-length of the hypopharyngeal sclerite. Labial and epipharyngeal sclerites located between the anterior parts of the lateral plates of the hypopharyngeal sclerite. Parastomal bars light brown, slightly curved, about as long as hypopharyngeal sclerite. Pharyngeal sclerite light brown, darker brown in area of tentorial phragma, dorsal bridge, ventral bridge and connection of dorsal and ventral cornua; dorsal and ventral cornua hyaline to light brown, nearly equal length, ventral part of pharyngeal sclerite with cibarial ridges. Dorsal and ventral bridges distinctly protruding. Anterior sclerite absent.
Thoracic segments I–III. Paired anterior spiracles on thoracic segment I, each spiracle contains fan-shaped arranged tubules with slit-like openings at the apex (Figs 20 A, B), 17–27 tubules per row (median = 20.5, n = 19 rows of tubules from 10 larvae). The number of tubules on the sides of the same larva often differs by one to three tubules. The anterior margin of the first thoracic segment is covered with numerous rows of trumpet-shaped bristles, except on the dorsal part (Figs 20 A, C). Paired rudimentary spiracular openings laterally on third thoracic segment (Figs 20 I, 8 A).
The first thoracic segment bears 14 cuticular sensilla and the second and third thoracic segments bear 13 cuticular sensilla on each side of the body. Cuticular sensilla include pit-, papilla-, “hair”- and trifid (Keylin’s organ) sensilla (Figs 20 D–H). Spatial pattern of thoracic cuticular sensilla as in Fig. 8 A.
Abdominal segments I–VII. Abdominal segments I–VII bear 13 cuticular sensilla on each side of the body and a pair of rudimentary lateral spiracles (as in Fig. 8 A). Creeping welts of abdominal segments I–VII (CW1–7) consist of several rows of pointed, more or less curved and symmetrical to asymmetrical spinules, the row pattern varies between different abdominal segments. CW1 (Fig. 21 A): three rows of spinules of approximately equal size, first and third row continuous, middle row consists of short, slightly curved row parts shifted relative to each other. All spinules directed posteriorly. CW2 (Fig. 21 B): Two discontinuous or incomplete rows (rows b) followed by a continuous central row (row c); below that short rows with large spinules placed on raised ridges (rows d) arranged as follows: two short horizontal central rows, each consisting of two groups of large spinules each, seven to nine large spinules in each group, between them ca. three large spinules, horizontal central rows laterally flanked by six inclined curved rows angled to the body midline with spinules becoming smaller towards the midline, posterior row of creeping welt (row e) with continuous small spinules; all spinules of abdominal segment II directed posteriorly. CW3 – CW7 (Fig. 21 C): similar to CW2, but additional anterior row (row a) with anteriorly directed spinules, all other spinules directed posteriorly. The inset in Fig. 21 C shows that large spinules in row d form only a single row, but sometimes there is a trace of a second row at the lateral edges of the two central parts on raised ridges (Fig. 9 I, arrow).
Caudal segment bearing 13 cuticular sensilla on each body side (Figs 21 E, 8 B, C). Caudal creeping welt CW8 similar in structure like CW3 – CW7, but the last row is arranged along the an terior margin of the perianal pad with anteriorly oriented spinules. Large bristles not as regularly distributed as in previous creeping welts, and oriented upward rather than posteriorly (Fig. 21 D).
Posterior spiracles (Figs 9 A, 21 G) sclerotised, slightly elevated, oval-angular, length 0.4–0.5 mm (median = 0.44, n = 12), width 0.36–0.48 mm (median = 0.42, n = 12), shortest distance between spiracles 0.06–0.18 mm (n = 19). Spiracular plate with roundish ecdysial scar and three very long spiracular slits meandering from area of the ecdysial scar to the edge of the spiracular plate in about 9–15 turns, terminal turns forming a large loop ending in a small roundish hook, large loop less pronounced in spiracular slit 1 (Fig. 21 G); spiracles usually black (paler in newly molted larvae), but yellowish along spiracular slits, yellow area (stripe) gradually widening from ecdysial scar to edge of spiracular plate, becoming club-shaped at large terminal loop and with blurred margins (Fig. 9 A). The spiracular slits are surrounded by four groups of bifurcate spiracular hairs that branch 2–3 times and end in acute tips (Fig. 21 G). Most hair groups consist of central unbranched hair trunks and two outer branched hair trunks (i.e., two hair trunks originating from the same place), number of hairs as follows (n = 4 spiracles): Hair group 1: 7–8 hair trunks (double trunks count as one hair), Hair group 2: 1 double trunk, Hair group 3: 5–6 hair trunks, Hair group 4: 10–11 hair trunks; Hair groups 1, 3, and 4 located along the central parts of the spiracular slits, group 2 located between spiracular slits 1 and 2 and slightly closer to the center of the spiracle. The number of hairs on the right or left spiracle of the same specimen often differs.
Anal complex: perianal pad rectangular, anal hook at posterior end of anal slit with sharp points (Fig. 21 F), spinules other than those of CW8 absent.
Puparium (Fig. 9 G). Length 6–9.2 mm; maximum width at abdominal segments 3 and 4 = 1.9–2.9 mm (n = 3); reddish to reddish brown, darker at both ends; oblong, strongly tapering at anterior end, broad at posterior end; anterior spiracles, posterior spiracles and creeping welts as in third instar larva.
Etymology. The species name means “two” in Latin and is used as a noun in apposition; it reflects the wing pattern, which resembles the number “2”.
Remarks. Aspistomella duo larva differed from A. tres by having only one row of large spinules in the central part of rows d (Fig. 21 C, see inset), whereas A. tres had a double row of spinules (Fig. 47 C, see inset). The posterior spiracles of A. duo and A. tres were relatively similar, but in A. duo the yellow meandering line above the spiracular slits ended in a club-shaped structure with blurred margins (Fig. 9 A), whereas in A. tres the widening of the yellow line was less pronounced and its edges remained distinct (Fig. 9 B). Furthermore, the spiracular slits 1 and 2 of A. tres were usually symmetrical and the distance between the spiracles was much smaller than in A. duo (see sd/sw index, Table 2).
Biology. Adult Aspistomella duo were often seen walking up and down on the surface of upright bamboo stems of Guadua angustifolia subsp. chacoensis (Figs 1 B, C). Occasionally, they dabbed at the bamboo surface with their proboscis and spent particularly long periods feeding on plant wounds caused by saws or knives, for example on felled bamboo culms. When approached, the flies would retreat to the opposite side of the bamboo culm or fly away.
Larvae of Aspistomella duo inhabited water-filled bamboo internode cavities of young bamboo culms that had emerged during the previous bamboo shoot season (Fig. 1 D). They used small holes made by moth larvae of Crambidae (Lepdidoptera, Figs 1 E, F) to enter the internodes. They were not found in older bamboo culms or in culms with large holes, possibly made by beetles (oval holes, about 6 × 3 mm), woodpeckers (slit-like holes, about 10 × 3 mm) or other animals.
Each infested internode was inhabited by a single crambid larva and had only one entrance tunnel. The crambid larvae spanned a protective web inside the internode cavity and fed near the web on the surface layer of the inner bamboo wall. As they developed, the larvae gradually enlarged their entrance tunnel transforming it into an exit hole before pupating inside the internode.
The culms of Guadua angustifolia were about 10 m high (n = 2). Each infested culm contained several internodes punctured by Crambidae. The length of the infested internodes was 20–40 cm (n = 3), the diameter was 9 cm (n = 1) and the thickness of the bamboo walls was 17–40 mm (n = 2). The crambid entrance tunnels were round and located in the upper half of the internodes (10.5–28 cm above the internode base, n = 3). The outer diameter of the entrance tunnels ranged from 0.42 to 0.93 mm (n = 5), the inner diameter from 1.64 to 3.93 (n = 4). Internodes inhabited by A. duo and other Ulidiidae were found at heights between 2.5 and 8.5 m (n = 8).
Larvae of Aspistomella duo were easily identified in the field by their white colour, muscoid shape with a broad posterior end, and especially by the roundish black spiracles (Fig. 1 H, I). In water-filled internodes, larvae remained on wet bamboo walls near the water surface, walked along the bottom of the internode while submerged, or floated with their posterior spiracles attached to the water surface (Fig. 1 G). Larvae were positively buoyant and could quickly rise to the water surface to obtain fresh air. Floating larvae occasionally began to swim by vigorously bending their bodies up and down. When walking on land or submerged in water, the larvae constantly moved their mouthparts. In some cases, the internode cavities were dried up, causing the larvae to congregate at the bottom of the internode, where they formed a clump until the next rainfall (Fig. 1 H). Mature larvae were able to jump and leave their internodes through the enlarged crambid holes to pupariate. The number of larvae inhabiting a single internode often exceeded 100 individuals, but sometimes they belonged to different Aspistomella or Ulivellia species.
Aspistomella duo larvae shared their habitat with larvae of Crambidae, sometimes also with other Ulidiidae (A. tres, Ulivellia tenoris, U. arcuata), aquatic dipteran larvae of Phoridae, Syrphidae (Fig. 1 I), an unidentified pearshaped aquatic dipteran and terrestrial larvae of Nitidulidae (Coleoptera).
description: Published as part of Kovac, Damir, Kameneva, Elena P., Korneyev, Severyn V., Araújo, Alexandre Santos, Savaris, Marcoandre, Smit, John T., Schneider, Alexander, Schreiber, Robert & Korneyev, Valery A., 2024, Revision of the Aspistomella group of genera (Diptera: Ulidiidae: Pterocallinae: Lipsanini), pp. 1-117 in Zootaxa 5530 (1) on pages 27-39, DOI: 10.11646/zootaxa.5530.1.1, http://zenodo.org/record/14023149