(Diptera: Vermileonidae) from China

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Zootaxa 3790 (3): 487–494 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2014 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3790.3.7 http://zoobank.org/urn:lsid:zoobank.org:pub:E8E3D090-66FC-4DE9-B8BE-4C3920E63BB1 Description of the larva and biological notes on Vermiophis taihangensis Yang & Chen, 1993 (Diptera: Vermileonidae) from China

O.G. OVTSHINNIKOVA1, ZHILIANG WANG2, A.N. OVCHINNIKOV1, XINLI WANG 2 & V. A. KRIVOKHATSKY1 1Zoological Institute, Russian Academy of Sciences, St. Petersburg 199034, Russia 2Department of Entomology, China Agricultural University, Beijing 100094, China

Abstract

Unmixed colonies of larval antlions and wormlions in similar pits were found in the Xiaolongmen National Forest Park in the Taihang Shan, China. A male of Vermiophis taihangensis Yang & Chen, 1993 was reared from a larva and a morphological description of the third instar larval wormlion is presented. The larva of Vermiophis taihangensis differs from the related species V. ganquanensis Yang, 1979 in the well developed sclerotized stigmata on abdominal segment 4, but is similar in the structure of the lateral row of setae and the same number of spines (6) on the pseudopod on the abdominal segment 1.

Key words: Diptera, Neuroptera, Vermileonidae, wormlions, antlions, larval biology, larval morphology

Introduction

In this paper, new data on the biology and larval morphology of these rare flies, featured in the book “Demons of the Dust” (Wheeler, 1930), are given. Information on coterminous colonies of the antlion Euroleon coreanus Okamoto, 1926 (Neuroptera, Myrmeleontidae) and the wormlion Vermiophis taihangensis Yang & Chen, 1993 (Diptera, Vermileonidae) in the Taihang Mountains (Hebei Province, China) is given, and a morphological description of the wormlion larva is presented. Pitfall traps of antlion larvae of the subfamily Myrmeleontinae (with about 100 species in the world fauna), mostly from the genera Myrmeleon Linnaeus and Euroleon Esben- Petersen, are well known. Larvae of the Vermileonidae are the wormlions that construct pitfall traps for the purpose of capturing prey. Vermileonidae constitute a more rare taxocene in closely related semiarid cenoses; about 40 species are known in this family in the World (Palaearctic, Nearctic, and Afrotropical regions).

Material and methods

The study was conducted 6–8 VII 2006 in a human-destroyed forest landscape close to the Beijing—Lhasa Road in Hebei Province, at the boundary of the Xiaolongmen National Forest Park (Taihang Mountain). Larvae of Vermiophis taihangensis were collected on Taihang Mountain (1100 m elevation) ca. 100 km west of Beijing. The reared adult was identified using the key in Nagatomi et al. (1999); the larva has not been previously described. The antlions larvae were determined using the key in Krivokhatsky (2011). Colonies (separate groups of pits) of both the antlion and the wormlion were found in similar sandy or dusty places at rock borders, in small hollows in slopes or along their bases. Several wormlion larvae were collected for rearing in the laboratory and description. The names of morphological structures follow the Manual of Palaearctic Diptera (Nagatomi, 1997), other terms, also used in dipterology (Teskey, 1981; Ludwig et al., 1996, 2001), are placed in brackets. The photographs were taken by Victor Krivokhatsky, Andrey Ovchinnikov and Wang Zhiliang.

Accepted by N. Evenhuis: 13 Feb. 2014; published: 22 Apr. 2014 487 Description of third instar larva

In nature, pale brown larvae are situated in the dusty or sandy pit and are covered with substrate (Fig. 1). When a wormlion is waiting for prey, it remains in the pit covered with the substrate, straightened stick-like or coiled, but when attacking, it catches the prey by coiling around it. Body length is 25 mm; body of the fixed third instar larva is sclerotized, pale brown (Fig. 2), with indistinct segmentation (Fig. 3), covered with microtrichia and with lateral row of papillae, bearing ventrally curved setae, placed at the flattened indistinct lateral pads. Vermicular 11-segmented body consisting of head capsule, permanently retracted within thorax, the 3- segmented thorax, and 8 segments of abdomen. There are 8 abdominal segments, each with 2–4 false segments. Large flat indistinct locomotory pads present on every abdominal segment, and covered with sparse very small hairs (invisible in Figs. 2, 3). Abdominal segment 1 with single mid-ventral pseudopod (proleg) with 6 subapical rigid spines (Fig. 4). Segment 4 with a pair of rounded sclerotized spiracles (stigmata) (Fig. 6). Caudal part of body wider; segments 6 and 7 widest, with distinct, well-developed locomotory pads (Fig. 3). Segment 7 dorsally with two comb-like rows of spines. Posterior row comprising 14 long spines (Fig. 5), anterior row with about the same number of short spines. Other reduced and incised comb-like rows situated on the dorsal part of the false segment 7 and of segment 6 (Fig. 3). Segment 8 terminating in 4 flat, broadly finger-shaped lobes (Fig. 3, inset). At the base of 1st and 2nd pairs of ‘fingers’ in the middle of last abdominal segment the anal opening is situated in the form of a longitudinal slit evident in certain positions in microscope and not visible in our photo. Most features of the third instar larva are preserved at the puparium stage, but our pupal exuvium is entirely covered with grains of sand (Fig. 7). The parts of the larval head were not dissected, as we have only one specimen of the third instar and one pupal exuvium for description only.

Comparison

The mid-ventral pseudopod of Vermileo Macquart and Vermitigris Wheeler has 5 spines (Nagatomi et al., 1999). One species of the genus Vermiophis Yang, V. ganquanensis Yang, has 6 (rarely 8) spines (Yang, 1979); other species, V. tibetensis Yang & Chen has 7 spines (Ludwig et al., 2001). Thus, Vermiophis can be characterized by the presence of 6–8 spines. Closely related species, V. taihangensis and V. ganquanensis have similar structure of the lateral row of papillae, terminated with setae, but locomotory pads in V. ganquanensis are well developed. Moreover, Vermiophis taihangensis differs from V. ganquanensis in the much more heavily sclerotized abdominal stigmata. The abdominal comb is an apomorphic structure of the family Vermileonidae, and most representatives have 16–20 long spines in the comb. Among known larvae only Vermileo spp. have 10–14 long spines. Thereby Vermiophis taihangensis has deviated from known Vermiophis (Ludwig et al., 2001) to Vermileo.

Biology

Larvae of V. taihangensis inhabit small sandy patches under rocks, where they build pits very similar to those of antlions. The colonies of 7–22 larvae, with each individual in its own pit, were situated in similar sandy or dusty places along the rock borders or in hollows. Colonies of wormlions could not be distinguished from antlion colonies by outward appearance as shown in the pictures (Figs. 9, 10) that were taken after collecting the larvae. Sometimes the colonies of different species were situated very close to each other (about 20 cm), but no mixed colonies were found. These data indicate that these two generalist predators do not make mixed colonies. The cohabitation of antlion and vermilion species in Dalmatia (Devetak, 2008) is an exceptional example. Collected larvae of vermilions and antlions were bred in laboratory conditions in St. Petersburg, Russia. The antlion species, Euroleon coreanus Okamoto, 1926 emerged from cocoons in June 2006. Wormlions had not completed their development before winter and were placed in a refrigerator for 4 months, but most of the larvae died during this time period as 2nd and 3d instars. Only one male Vermiophis taihangensis emerged 01 May 2007 (Fig. 8).

FIGURE 2. Vermiophis taighanensis, larva, in alcohol.

WORMLION LARVA Zootaxa 3790 (3) © 2014 Magnolia Press · 489 FIGURE 3. Vermiophis taighanensis, larva, lateral view; inset, finger-shaped lobes of the caudal part of abdomen, ventral view. Abbreviations: ab—abdomen, 1–8 segments; l ab 8—abdominal lobes, 8 segment; p l—proleg; sp—spiracles; th—thorax, 1–3 segments.

FIGURE 4. Vermiophis taighanensis, larva, mid-ventral pseudopod (proleg) of 1st abdominal segment.

FIGURE 6. Vermiophis taighanensis, larva, spiracles (stigmata), lateral view.

FIGURE 9. Colony of antlion Euroleon coreanus.

Acknowledgements

The authors are very grateful for the assistance to Dr. Stephen D. Gaimari, California Department of Food and Agriculture, Sacramento, CA, USA, also to Dr. Boris A. Korotyaev, Zoological Institute RAS, St. Petersburg, Russia, and Domenico Otranto, Professor of Parasitic Diseases Department, Veterinary Medicine University of Bari, for language improvement and wholesome assistance. The study was financially supported by the National Natural Science Foundation of China (No. 30270186).

References

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