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Research Article
The first breeding record of a small-headed fly (Diptera, Acroceridae) from a huntsman spider (Araneae, Sparassidae)
expand article infoYung-Kai Shih‡, Christian Kehlmaier§
‡ Department of Life Science, National Taiwan Normal University, Taipei City, Taiwan
§ Senckenberg Natural History Collections Dresden, Museum of Zoology, Dresden, Germany

Corresponding author: Christian Kehlmaier ( christian.kehlmaier@senckenberg.de )

Academic editor: Mehmet Yaran
© 2026 Yung-Kai Shih, Christian Kehlmaier.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Shih Y-K, Kehlmaier C (2026) The first breeding record of a small-headed fly (Diptera, Acroceridae) from a huntsman spider (Araneae, Sparassidae). Contributions to Entomology 76(1): 133-138. https://doi.org/10.3897/contrib.entomol.76.e190444
ZooBank: urn:lsid:zoobank.org:pub:96FD4863-04CA-44D0-85D4-002125592F8C
Open Access

Abstract

An acrocerid breeding record of an unidentified Ogcodes Latreille, 1796 species from the huntsman spider Gnathopalystes taiwanensis Zhu & Tso, 2006 captured and reared in Taiwan is provided, representing the first breeding record of Acroceridae from Sparassidae. The obtained male Ogcodes is compared to the male holotype of Ogcodes taiwanensis Schlinger, 1971, being currently the sole described representative of the genus known to occur in Taiwan. A species list of the four Acroceridae species known from Taiwan is provided, all of them being endemic to the island.

Key Words

Host-parasitoid interaction, hunchback fly, parasitoids, spider fly, Taiwan

Introduction

Acroceridae have rarely been recorded from Taiwan in the past. To our knowledge, only four named species have been cited so far, all of them being considered endemic to the island (Chung and Shao 2025). Breeding records of Acroceridae are largely based on incidental findings by arachnologists, collecting subadult spiders and taking them into the lab in order to breed them to adulthood for unambiguous species identification. Most Acroceridae larvae develop as endoparasitoids in the opisthosoma of true spiders (Araneae), leaving them shortly before or after the spider undergoes its final moult. Known exceptions comprise the Neotropical Sphaerops appendiculata Philippi, 1865, developing in an ectoparasitic mode on Ariadna maxima (Nicolet, 1849) (Schlinger 1987). Mature larvae often seem to induce an aberrant web-building behaviour in the hosts previous to their emergence, the resulting web serving the acrocerid as a “cradle” or shelter during pupation (Winterton and Barraclough 2017). A synopsis of the life history of Acroceridae is provided by Schlinger (2003).

Material and methods

On 10 May 2024, several subadult specimens of the huntsman spider Gnathopalystes taiwanensis Zhu & Tso, 2006 were collected in Yangmingshan, northern Taiwan (25°7.976658'N, 121°32.141052'E) by the senior author. The spiders were kept in the lab for rearing on moistened wet wipes and leaves and at 28 °C with a light cycle of approximately 10 hours of light and 14 hours of darkness. All except one parasitised specimen developed to adulthood and were identified via the morphology of the genitalia using Zhu and Tso (2006). The identification of the acrocerid fly was achieved with Winterton and Gillung (2012).

After emergence of the acrocerid larva from the spider, the host and each larval development stage were documented with a Panasonic Lumix DMC-LX5 digital camera, with subsequent processing of the images using ImageJ. Micrographs of the reared Ogcodes sp. were taken with a Zeiss Axiocam 712 colour, equipped on a Zeiss AXIO Zoom.V16.

The adult Ogcodes sp. is preserved in ethanol at Senckenberg Natural History Collections Dresden, whereas the spider remains are preserved dry and are deposited at the Systems and Evolutionary Biology Laboratory, Department of Life Science, National Taiwan Normal University.

The type specimen of Ogcodes taiwanensis Schlinger, 1971 is currently placed in the collection of the late E. I. Schlinger housed at the California Academy of Sciences Entomological Collection in San Francisco (courtesy of Christopher C. Grinter), but is in the process of being returned to the Institute for Agro-Environmental Sciences, NARO, Tsukuba (formerly National Institute of Agricultural Sciences, Tokyo).

Results

Description of Parasitism (Figs 1, 2)

The host species recorded is Gnathopalystes taiwanensis (Fig. 1A), a small green huntsman spider (Zhu and Tso 2006). Before the mature acrocerid larva emerged from the spider’s body, the spider sealed the entrance of its silk retreat, completely closing itself inside. This suggests that parasitism might influence the host’s behaviour (Fig. 1B). About 24 hours after the spider was collected, the mature acrocerid fly larva emerged from the side of the host’s abdomen (Fig. 2A), killing its host. After emerging, the larva began constructing silk threads on the surface of a leaf (Fig. 2B). Approximately 24 hours later, the larva excreted black meconium and entered the pupal stage (Fig. 2C). On the third day of the pupal stage, the body started to darken (Fig. 2D). On the fourth day, the adult fly began to eclose (Fig. 2E) and around 20 hours later, the body colour darkened (Fig. 2F). Two days after eclosion, the adult fly excreted white meconium and began moving around. The development period from mature larva to adult fly lasted for about 8 days.

Figure 1. 

Host spider and spider nest (10 May 2024, at 20:00 local time). A. Host spider shortly before the emergence of the spider fly larva; B. The closed spider’s nest (10 May 2024, at 23:00 local time). Scale bar: 10 mm.

Figure 2. 

Pupal development of Ogcodes sp. A. The larva emerged from the spider’s abdomen (11 May 2024, at 9:30 local time); B. The stretched larva (12 May 2024, at 4:30 local time); C. The larva excreted black meconium (indicated by the arrow) and pupated (13 May 2024, at 3:15 local time); D. The pupa’s colour darkened (15 May 2024, at 0:30 local time); E. The adult shortly after eclosion (16 May 2024, at 1:45 local time); F. The eclosion was complete and the insect’s colour darkened (16 May 2024, at 22:15 local time); G. The adult excreted white meconium (indicated by the arrow) and began to be active (18 May 2024, at 4:00 local time). Scale bar: 5 mm.

Description of male Ogcodes sp. (Fig. 3)

Head. Dark brown, except antenna with pedicel yellowish; setae on back of head yellowish. Thorax. Scutum, postpronotal lobes, postalar calli, pleurae, scutellum and subscutellum dark brown and shining; setae all yellowish. Legs. Yellow, except dark brown at coxa (but hind coxa yellow anteriorly), trochanter, very narrowly at base of femur, distinctly at femoral-tibial joints, tarsal segments 2–5 and claws; setae yellowish. Wings. Halter with pale stem and knob dark brown; squama with rim dark brown and brown surface; wing membrane brownish tinged, especially in anterior half; veins pale brown. Abdomen. Tergites predominantly dark brown, shining and with yellowish setae; tergites 1–5 narrowly yellowish pale along posterior margins; tergites 2–3 and, to a lesser extent, also tergite 4, yellowish pale laterally, clearly visible also from dorsal view; sternites narrowly dark brown along anterior margin (extending more towards lateral margins), yellowish in middle and whitish along posterior margins, shining and with yellowish setae. Terminalia. Not dissected, dark brown.

Figure 3. 

Microphotographs of male reared Ogcodes sp. A. Dorsal view; B. Ventral view; C. Frontal view; D, E. Lateral view. Scale bar: 1 mm.

Differential diagnosis (Figs 3, 4)

Compared to the original description of male O. taiwanensis, the male Ogcodes sp. at hand differs by a yellowish pedicel (not dark brown), oral region dark brown (not brownish-yellow), thorax dark brown (not postpronotal lobes, scutum, postalar calli and scutellum partly/largely yellowish), wing membrane brownish (not hyaline), abdomen with yellow lateral regions on tergites 2–3 less distinct, tergite 4 weakly yellowish laterally (not dark brown), sternites anteriorly narrowly dark brown (not entirely yellowish-white, except for sternite 2 which has small dark anterolateral spots).

Figure 4. 

Microphotographs of male holotype of O. taiwanensis. A. Dorsal view; B. Lateral view. Scale bar: 1 mm.

Discussion

The systematics of the almost cosmopolitan genus Ogcodes Latreille, 1796 is poorly understood. Currently, 115 species are being considered (Winterton and Barraclough 2017), making Ogcodes the species-richest genus of Acroceridae (Nearctic: 17 (Schlinger 1981); Neotropic: 9 (Schlinger 1960); Afrotropic: 10 (Winterton and Barraclough 2017); Palaearctic: 27 (Nartshuk 1988); Oriental: 16 (Schlinger 1960, 1971); Australasia: 23 (Schlinger 1960); Polynesia: 3 (Schlinger 1960)). The latest world revision was presented by Schlinger (1960) who later described six additional Oriental species, including O. taiwanensis (Schlinger 1971). Differentiation of the individual species is largely based on external morphological features which might show some degree of variability. So far, phenotypic plasticity regarding body size and colouration within a single sex of a species of Ogcodes has never been investigated in detail, but a study on Acrocera orbiculus (Fabricius, 1787) showed that the observed variability can be very large, potentially leading to an oversplitting of species (Kehlmaier and Almeida 2014). For these reasons, we currently refrain from officially describing and naming the reared male of Ogcodes. Instead, we hope our finding will encourage additional collecting efforts in Taiwan in order to increase the available material at hand. This should best be achieved by a mixture of collecting techniques, such as Malaise trapping, hand netting and by rearing of possible host spiders.

So far, host data for more than 60 Acroceridae taxa (about 10% of the world fauna), recorded from 25 spider families, have been gathered (Gillung and Borkent 2017). Including the current observation, members of Ogcodes have been reared from 16 families of Araneomorphae: Agelenidae, Amaurobiidae, Anyphaenidae, Araneidae, Cheiracanthiidae (= Eutichuridae), Clubionidae, Desidae, Gnaphosidae, Lycosidae, Oxyopidae, Philodromidae, Salticidae, Sparassidae, Theridiidae, Thomisidae and Trachelidae (Gillung and Borkent 2017). This listing results from 95 acrocerid-spider interactions summarised or observed by Gillung and Borkent (2017), Yuan et al. (2019), Abhijith et al. (2022), Hagopián and Laborda (2023), Kehlmaier et al. (2024) and Shih and Kehlmaier (present study).

Acroceridae have rarely been recorded from Taiwan in the past. Only four named species from three subfamilies have been cited, all of them being considered endemic to the island: Ogcodinae—Ogcodes taiwanensis Schlinger, 1971; Cyrtinae—Hadrogaster formosana (Shiraki, 1932); Nipponcyrtus taiwanensis (Ôuchi, 1938); Philopotinae—Oligoneura takasagoensis (Ôuchi, 1942). In addition, Schacht (2010) recorded eight unidentified acrocerid flies from various localities. Six of these flies are currently deposited in the Bavarian State Collection of Zoology (Zoologische Staatssammlung München) and belong to Hadrogaster formosana (one specimen, Meifeng, N-Nantou County, Road No. 14, NE Puli, Meifeng Experimental Farm, ca. 24°06'N, 121°10'E, 2200 m a.s.l., 9–11 Sep. 2002) and Oligoneura sp. (one specimen, Fushan Botanical Garden, ca. 24°46'N, 121°35'E, 650 m a.s.l., 7–9 May 2001; four specimens, Tengir, Kaohsiung County, Jungyang Mountains, Tengir Endemic Species Research Institute, ca. 23°07'N, 120°47'E, 1700 m a.s.l., 14–19 Sep. 2002). It can be assumed that the true diversity of this Diptera family in Taiwan is considerably higher than currently known.

Acknowledgements

We thank Christopher C. Grinter (San Francisco) for providing photos of the holotype of O. taiwanensis and André Reimann (Dresden) for providing photos of the reared Ogcodes. Dieter Doczkal (Munich) supported us by tracking down the material of the late Wolfgang Schacht.

References

  • Abhijith APC, Hill DE, Ramesh S (2022) Hunchback flies (Diptera: Acroceridae) as endopredators of jumping spiders (Araneae: Salticidae). Peckhamia 274.1: 1–6.
  • Chung K-F, Shao K-T (2025) Catalogue of life in Taiwan. http://taicol.tw/ [accessed 27 October 2025]
  • Hagopián D, Laborda A (2023) New records of spider flies (Diptera: Acroceridae) in neotropical jumping spiders (Araneae: Salticidae). Entomological Communications 5: ec05034. https://doi.org/10.37486/2675-1305.ec05034
  • Kehlmaier C, Almeida J (2014) New host records for European Acroceridae (Diptera), with discussion of species limits of Acrocera orbiculus (Fabricius) based on DNA-barcoding. Zootaxa 3780(1): 135–152. https://doi.org/10.11646/zootaxa.3780.1.5
  • Kehlmaier C, Schäfer M, Reimann A, Ares AM (2024) New host records of West Palaearctic spider flies (Diptera: Acroceridae). Integrative Systematics 7(1): 49–57. https://doi.org/10.18476/2024.479160
  • Nartshuk EP (1988) Family Acroceridae. In: Soós Á (Ed.) Catalogue of Palaearctic Diptera, vol. 5. Elsevier, 186–196.
  • Schacht W (2010) Report on three collecting trips to Taiwan (Insecta: Diptera). Entomofauna 31(5): 33–48.
  • Schlinger EI (1960) A revision of the genus Ogcodes Latreille with particular reference to species of the Western Hemisphere. Proceedings of the United States National Museum 111: 227–336. https://doi.org/10.5479/si.00963801.111-3429.227
  • Schlinger EI (1971) Descriptions of six new species of Ogcodes from Borneo, Java, New Guinea, Taiwan and the Philippines. Pacific Insects 14: 93–100.
  • Schlinger EI (1981) Acroceridae. In: McAlpine JF, Peterson BV, Shewell GE, Teskey HJ, Vockeroth JR, Wood DEM (Eds) Manual of Nearctic Diptera, vol. I. Research Branch Agriculture Canada, Monograph 27: 575–584.
  • Schlinger EI (2003) Acroceridae, Spider-Fly Endoparasitoids. In: Goodman SM, Benstead JP (Eds) The Natural History of Madagascar. University of Chicago Press, 734–740.
  • Winterton SL, Barraclough DA (2017) Acroceridae (small-headed flies or spider flies). In: Kirk-Spriggs AH, Sinclair BJ (Eds) Manual of Afrotropical Diptera. Volume 2. Nematocerous Diptera and lower Brachycera. South African National Biodiversity Institute, 981–993.
  • Winterton SL, Gillung JP (2012) A new species of spider fly in the genus Sabroskya Schlinger from Malawi, with a key to Acrocerinae world genera (Diptera, Acroceridae). ZooKeys 171: 1–15. https://doi.org/10.3897/zookeys.171.2137
  • Yuan D, Li X, Yeates DK, Rodriguez J (2019) Unlucky spider flies (Diptera: Acroceridae) trapped in a tomb of mud: An Australian predatory wasp (Sphecidae) provisions its nest with parasitised spiders (Salticidae). The Pan-Pacific Entomologist 95(3–4): 109–115. https://doi.org/10.3956/2019-95.3.109
  • Zhu MS, Tso IM (2006) Two new species of the family Sparassidae from Taiwan, with description of the female of Olios scalptor (Arachnida: Araneae). Bulletin of the British Arachnological Society 13: 267–270.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Artificial Intelligence (AI) use

The authors accept full responsibility for the content of the manuscript, including the disclosure of any use of AI.

No AI tools were used in the preparation of this manuscript.

Funding

No funding was reported.

Author contributions

All authors have contributed equally.

Author ORCIDs

C. Kehlmaier https://orcid.org/0000-0001-9622-0566

Data availability

All of the data that support the findings of this study are available in the main text.

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