Taiwanon sp.

Zheng, Yuchen, Li, Xuankun, Yao, Gang & Liu, Xingyue, 2024, Myrmeleon shalulianus sp. nov. (Neuroptera: Myrmeleontidae), and the first record of Taiwanon bee fly (Diptera: Bombyliidae) on Myrmeleon trigonois in China, Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 64 (1), pp. 47-66 : 59-64

Taiwanon sp.

Chinese common name: ÛOiAE

( Figs 10–12 )

Material examined. CHINA: CHONGQING: 2♀♀ (emerged 3.viii.2023 from larvae of Myrmeleon trigonois ), Wuxi County, Lanying Township, Lanying Village, 900 m, 17.v.2023, Yuchen Zheng ( CAU).

Description. Adult (female). Head about 1.5× wider than long, mostly black with sparse pale pruinescence and covered in short black hairs and short white to pale yellow scales. Eyes dichoptic. Frons triangular with sparse pale pruinescence, 9.0× length of ocellar tubercle, 3.1× as wide as ocellar tubercle, upper half with short black hairs; lower half as long as upper half, with admixed short black hairs and short pale yellow scales. Ocellar tubercle slightly raised, blackish brown to black with sparse grey pruinescence, with short blackish hairs. Face with thick pale pruinescence and admixed short black hairs and short white to pale yellow scales, denser than frons but dorsal lateral area (below antenna) bare. Gena narrow, with thick pale pruinescence. Clypeus with thick pale pruinescence and otherwise bare. Occiput with thick pale pruinescence and sparse short white scales, margin of cavity with admixed dense short white scales and sparse short black hairs. Posterior eye margin deeply indented with narrow line dividing facets.Antenna black with thick brownish pruinescence, scape and pedicel with short black hairs, hairs denser and longer ventrally; flagellum bare. Scape 1.9× as long as wide, and 2.8× as long as pedicel, uniform from base to apex. Pedicel 0.8× as long as wide. Flagellum 12.0× as long as wide, 1.2× as long as scape + pedicel, 1.3× as long as scape, one-segmented with apical stylus. Palpus rudimentary, not extending beyond oral cavity, yellow with apically black, with short black hairs, one-segmented, without palpal pit. Mouthparts slender, not extending beyond oral cavity, brownish yellow with short brownish hairs.

Thorax. Integumental colour of scutum mostly black with sparse grey pruinescence. Scutum covered with white scales, hairs denser marginally, without distinct bristles. Scutellum black with sparse grey pruinescence, covered with short white scales. Pleura black with thick grey pruinescence, proepisternum densely covered in long black hairs, posterodorsal half of anepisternum with admixed dense long white scales and sparse black hairs, anteroventral area of anepisternum with black hairs, katepisternum with black hairs and ventral half admixed with pale yellow scales, anepimeron with pale yellow scales and black hairs, laterotergite and mediotergite with dense long white scales, proepimeron, meron, and metapleuron bare.

Legs mostly brown except for blackish brown femora, femora mostly covered in yellow scales and ventral half with black hairs, tibia mostly covered in blackish brown scales, except for ventroposterior face of middle femur that is covered with dense long white and black hairs. Bristles on legs black. Fore tibia 3.5× longer than fore basitarsus, middle tibia 3.1× longer than middle basitarsus, hind tibia 3.0× longer than hind basitarsus.

Wings. Wing membrane hyaline. Cell r5 open; cell br longer than cell bm, R2+3 arising from R4+5 right before crossvein r-m, crossvein r-m arising from basal half of cell dm; cell cua open ( Fig. 11D ). Stump vein present on R2+3, R4, and crossvein m-m ( Fig. 11D ). Haltere stem and knob blackish brown.

Abdomen. Integumental color of tergites black mostly with sparse grey pruinescence. Tergite 1 with dense white hairs and scales; tergites 2–3 with white scales and hairs on anterior half and black scales and hairs on posterior half; tergites 4–7 with black scales and laterally admixed with white scales. Sternites black with thick pale pruinescence, covered in black hairs and scales, laterally admixed with white scales.

Male. Unknown.

Pupal exuviae. Length: 9.0–11.0 mm. Head width: 1.7–2.0 mm. Thorax width: 2.3–2.8 mm.Abdominal width: 2.2–2.7 mm, tapering to 0.4–0.5 mm at anal segment. Coloration predominantly pale yellow, spines dark brown to black. Head armed with 3 pairs of cephalic spines. One anterior antennal process (aap) present, basal area with one dorsal short hair and one lateral long hair ( Figs 12G, H ). Two posterior antennal processes (pap) present, two pap as long as aap ( Figs 12G, H ). Median facial hair (mfha) absent, frontal spine (fsp) merged in middle. Labral sheath (lsh) without ventral subapical process. Proboscidal sheath (prsh) short, about 0.5 length of lsh, slightly rugose laterally. Maxillary sheath (msh) smooth, extending and connecting right after prsh. Palpal sheath (pash) rugose, extending slightly over lsh ( Figs 12C, D ). Posterolateral facial hair (plfha) absent. Thorax mostly smooth, posterior mesothoracic callosity (pmc) small and weak. Thorax bare, without hair around pmc. Wing sheath (wsh) and basal half of leg sheaths (lesh) smooth, apical half of lesh rugose ( Fig. 12D ). Wsh not reaching abdominal segment 3. Fore leg sheath (lesh 1) and middle leg sheath (lesh 2) not exceeding apex of wing sheath, hind leg sheath (lesh 3) reaching abdominal segment 3. Abdomen. Eight abdominal segments visible, segments 8 and 9 fused ( Fig. 12B ). Abdominal tergite 1 with a few sparse short hairs. Abdominal tergites 2 to 7 with well-developed chitinous rods with posterior apex raised as spines; long hairs present laterally and sometimes between two chitinous rods on tergites 2 to 7 ( Fig. 12E ). Generally longer and denser hairs but fewer rods in posterior abdominal segments. Tergite 8+9 with one tiny dorsal spine, posterolateral callosity absent. Abdominal pleura 2 to 7 and 8+9 each with row of long hairs. Sternites 2 to 7 with some sparse short hairs on posterior half. Sternite 8+9 bare. Anal segment smooth, ventral callosities small and weak ( Fig. 12J ). Dorsal posterolateral process (dpp) small, weak, and fused, ventral posterolateral process (vpp) short and acute, with one dorsal spine and one ventral spine of similar size ( Figs 12I, J ).

Host. Myrmeleon trigonois Bao & Wang, 2006 .

Bio-ecology. We observed the behavior of Taiwanon sp. parasitoid of two M. trigonois larvae. The parasitised larvae showed no abnormality from spin cocoons to pupation (we opened all the cocoons to observe the prepupa to pupa). It was not until a week after the parasitised M. trigonois larvae had pupated that we found the prepupa of Taiwanon sp. in the rearing cup. By that time, the pupae of M. trigonois had been consumed, their body fluids were drained, but their body surfaces were left entirely intact. We assume that larvae of Taiwanon sp. are endoparasitic and may be able to diapause for the period of host larvae until the host cocoons and pupates before rapidly consuming the host and pupating, allowing Taiwanon sp. to use the cocoons of M. trigonois to protect itself during its pupal stage. Considering that the two specimens of Taiwanon sp. are both females, we tentatively treat this species as an undetermined one.

Remarks. The present species is similar to Taiwanon phormae Evenhuis, 2018 . Without comparing the male genitalia, we are not sure whether it is the same species or not. To stay on the safe side, we prefer not to name a new species based on the available female specimens.

Variation in cell cua was observed. On the same specimen, cell cua was closed on the left wing and opened on the right wing ( Fig. 11A ). We described cell cua as open, based on the most common status of two observed specimens.

In the key to world genera of Villoestrini by EVENHUIS (2018), vein R4+5 curved downward or upward was used to discriminate Taiwanon and Oestranthrax . All R4+ 5 in EVENHUIS (2018) refer to R4 instead.

Figures

Fig. 10. Parasitoid Taiwanon sp. (Diptera: Bombyliidae) and parasitism of Myrmeleon trigonois Bao & Wang, 2006. A – pupa of Taiwanon sp., lateral view; B – pupa of Taiwanon sp., ready to emerge; C – living adult of Taiwanon sp.; D – remains of M. trigonois pupa (photos by Yuchen Zheng).

Fig. 11. Taiwanon sp., female. A – dorsal view; B – lateral view; C – wing; D – head, dorsal view; E – head, lateral view; F – head, lateral view; G – abdomen, dorsal view. (Photos by Haoyue Zhou).

Fig. 12. Taiwanon sp., female pupal exuvia.A – dorsal view; B – lateral view; C – head, ventral view; D – head and thorax, ventral view; E – abdominal segments 2–4, dorsal view; F – cephalic spines, dorsal view; G – cephalic spines, frontal view; H – cephalic spines, lateral; I – anal segment, dorsal view; J – anal segment, ventral. (Photos by Haoyue Zhou).