Frolov, A.V. 2008. New and little known species of the subgenus Aegialia (Silluvia) (Coleoptera, Scarabaeidae: Aphodiinae) from the Sino-Tibetan mountains. Zootaxa, 1712: 42–48.

New and little known species of the subgenus Aegialia (Silluvia) (Coleoptera, Scarabaeidae: Aphodiinae) from the Sino-Tibetan mountains

A.V. Frolov

Laboratory of Insect Systematics, Zoological Institute, Russian Academy of Sciences, Universitetskaya nab., 1, 199034 St.Petersburg, Russia. E-mail: afrolov@zin.ru

Abstract

Three new species of the subgenus Aegialia (Silluvia) Landin, 1949, are described from China: A. (S.) gansuensis, sp. n., A. (S.) igori, sp. n., and A. (S.) yunnanica, sp. n. Notes on the distribution and variability of A. (S.) kabaki Frolov, 2002, are given.

Key words: scarab beetles, taxonomy, new species, distribution, China.

INTRODUCTION  

Aegialia subgenus Silluvia Landin, 1949, comprises a number of externally uniform dark brown to black, elongate, small-sized beetles.  They are putatively detritophagous and occur in high altitudes in Himalaya and Sino-Tibetan mountains.  As a taxonomic group, Silluvia was only recognized in the mid-20th century.  It was originally described as a genus and a separate subfamily, Silluviinae Landin, was proposed for it.  A few species of Silluvia from China were later described by Petrovitz (1963), Stebnicka (1977), and Frolov (2002).  Stebnicka (1977) analyzed the data available to her and attempted reconstruction of phylogeny of the tribe Aegialiini.  On the basis of this analysis, she considered Silluvia a subgenus of Aegialia Latreille, 1807.  In the recent catalogs (Dellacasa 1988, Stebnicka 2006), however, the group is listed as a separate genus.  Until a more comprehensive phylogenetic analysis is conducted I have decided to treat the group as a subgenus of Aegialia.

Silluvia specimens are extremely rare in collections, but some have turned up among material from China that has accumulated in the Zoological Institute of Russian Academy of Sciences (ZIN) over a few past years.  In this material, I found three distinct species that cannot be classified as any of the described species.  They are different from known species in the shape of the parameres and internal sac sclerites and are therefore described as new in this paper.  Additional specimens of A. (S.) kabaki Frolov, 2002, showed considerable variability in the pronotal shape and provided locality data to better define the range of this species.

Taxonomic study of the subgenus Silluvia is complicated by the fact that most of the nominal species were described from single specimens and, in half of the cases, from females.  Species described from females were separated on the basis of the punctation of the head and the shape of stilus.  Interspecific variability of these characters was not, however, studied by the authors.  Examination of the material now available in the ZIN shows that these characters vary considerably and reliable identification of females is not always possible.

Habitus photographs were taken with a Leica MZ12 stereo microscope and photographs of aedeagi and internal sacs were taken with a Leica DMLB compound microscope from specimens in glycerol.  Distribution map was generated with ArcGIS software.  Coordinates of the localities were taken from the labels, if available, or from the NGA GEOnet Names Server (GNS, http://earth-info.nga.mil/gns/html/index.html).  All the specimens studied are deposited in the ZIN.

DESCRIPTIONS

Aegialia (Silluvia) yunnanica, sp. n.

Figs. 1-3, 13

Type material.  Holotype, male with the label "CH, W Yunnan, NE Fugong 26 56 30 N / 98 55 14 E 26 56 46 N / 98 56 13 E H=2690-3240 m, 30.05.2006, Belousov & Kabak leg."  Paratypes: 2 females with same label as the holotype; male with the label "China: Yunnan Lanping Co., Lajing, Fuhe vill., near Chanyanshan Pass, 20.VIII.2007."

Description.  Holotype, male (Fig. 1).  Body length 6.2 mm. Body uniformly black, shiny, tarsi testaceous.  Clypeus rounded, without emargination in the middle.  Genae indistinct, genal and frontoclypeal sutures almost absent, only feebly marked as smooth lines laterally.  Eyes very small in dorsal view.  Clypeus and frons densely, evenly punctate (punctures separated by 1 puncture diameter); anterior part of clypeus with sparser and smaller punctures.

Pronotum coarsely punctate (punctures separated by 1-2 diameters on disc, becoming denser laterally).  Lateral and basal margins coarsely punctate, posterior angles rounded and very slightly serrate.

Scutellum triangular, impunctate basally, shiny.

Elytra with strong humeral teeth.  Striae deep, punctate (punctures of striae separated by 2-3 puncture diameters, each puncture bears 1 minute yellow seta).  Intervals slightly convex, impunctate.

Anterior tibiae with short lateral teeth, tibial spur slightly curved inward.  Upper spur of hind tibia a bit shorter than tarsomere 1, tarsomere 1 as long as tarsomere 2-4 combined.

Parameres with well sclerotised apices distinctly protruding medially (Fig. 2).  Internal sac of aedeagus with 3 distinct sclerites, one of which is relatively long and depressed (indicated in Fig. 3).

Female.  Distinguished from male by the anterior tibial spur not curved inward, clypeus with only minute sparse punctures, slightly distinct genae, and upper spur of hind tibia being slightly longer than tarsomere 1.

Variability.  Body length of paratypes varies from 6.5-7.0 mm.  Posterior angles of the pronotum are weakly serrate in one specimen.

Differential diagnosis.  Aegialia (Silluvia) yunnanica sp. n. can be separated from other described Silluvia species by the parameres with well-sclerotised apices distinctly protruding medially and internal sac sclerites with one relatively long and depressed sclerite.  From A. shashi Stebnicka, 1977, it can also be separated by the densely and uniformly punctate head; and from A. (S.) kabaki and A. (S.) wassuensis (Petrovitz, 1963) by smooth posterior angles of pronotum.  Females of A. yunnanica are similar to the holotype of A. elongata Landin, 1948 (redescribed by Stebnicka 1977) but can be separated from it in having more sparsely punctate clypeus and by the first tarsomere being shorter then 3 following tarsomeres combined.

Distribution. Aegialia yunnanica sp. n. is known from western Yunnan Province of China (Fig. 13).

Etymology. The species name was derived from the Chinese Province of Yunnan, where the type series was collected.

Figs. 1-3. Aegialia (Silluvia) yunnanica, sp. n., holotype.
Figs. 1-3. Aegialia (Silluvia) yunnanica, sp. n., holotype.  Fig 1. Habitus  Fig. 2. Aedeagi in dorsal and lateral view.  Fig 3. Internal sacs of aedeagi. Scales: A – refers to Fig 1; B – refers to Figs 2, 3.

 

Aegialia (Silluvia) gansuensis, sp. n.

Figs. 4-6, 13

Type material.  Holotype, male with the label "CH, S Gansu, NNW Kaba Vill. 34 07 13 N / 103 25 03 E H=2780 m, 11.06.2006, Belousov & Kabak leg."  Paratypes: 2 females with the same data as the holotype; 1 male and 1 female with the label "CH, Sichuan, S Rilong 30 58 58 N/102 50 28 E 30 58 53 N/102 50 27 E 3355-3375 m, 27.08.2004, Belousov & Kabak leg.;" 1 female with the label "CH, Sichuan, E Rilong 31 00 11 N/102 52 38 E H~3475 m, 26.08.2004, Belousov & Kabak leg.;" 1 male with the label "China, C.Sichuan, E of Danba S of Guanyongchang Vill. 30 55 26 N/102 03 07 E H~3305 m, 10.08.2004, Belousov & Kabak leg."

Description.  Holotype, male (Fig. 4).  Body length 6.3 mm.  Body black, shiny, legs and lateral margins of pronotum somewhat reddish-black.  Clypeus rounded, without medial emargination.  Genae almost indistinct, genal and frontoclypeal sutures almost absent, only feebly marked as smooth lines laterally.  Eyes very small in dorsal view.  Frons coarsely and densely punctate except medially.  Clypeus sparsely punctate with small punctures.

Pronotum coarsely punctate (punctures separated by 1-2 diameters on disc, becoming denser laterally).  Lateral and basal margins coarsely punctate, posterior angles rounded and slightly but distinctly serrate.

Scutellum triangular, impunctate basally, shiny.

Elytra with strong humeral teeth.  Striae deep, punctate (punctures of striae separated by 2-3 puncture diameters).  Intervals slightly convex, impunctate.

Anterior tibiae with short lateral teeth; tibial spur slightly curved inward.  Upper spur of hind tibia a bit longer than tarsomere 1, tarsomere 1 slightly longer then tarsomere 2-4 combined.

Parameres short, relatively acute in lateral and dorsal view, apices feebly sclerotized (Fig. 5).  Internal sac of aedeagus with 3 distinct sclerites, one of which has a complex, subtriangular shape (indicated in Fig. 6).

Female.  Distinguished from male by the anterior tibial spur not curved inward.

Variability.  Body length of paratypes vary from 6.0-7.0 mm.

Differential diagnosis.  Aegialia (Silluvia) gansuensis sp. n. can be separated from other described Silluvia species by the relatively short, acute parameres (in lateral and dorsal view) and by the shape of internal sac sclerites (Fig. 6).  From A. shashi and A. sinica,it can also be separated by sparser punctation of the head; and from A. (S.) kabaki and A. (S.) wassuensis, by the smooth posterior angles of pronotum.

DistributionAegialia gansuensis sp. n. is known from Gansu and Sichuan provinces of China (Fig. 13).

Etymology.  The name of the species is derived from the Chinese Province of Gansu, where the holotype was collected.

Figs. 4-6, Aegialia (Silluvia) gansuensis, sp. n., holotype.
Figs. 4-6, Aegialia (Silluvia) gansuensis, sp. n., holotype.  Fig 4. Habitus  Fig. 5. Aedeagi in dorsal and lateral view.  Fig 6. Internal sacs of aedeagi. Scales: A – refers to Fig 4; B – refers to Figs 5, 6.

 

Aegialia (Silluvia) igori, sp. n.

Figs. 7-9, 13

Type material.  Holotype, male with the label "CH, N Sichuan, SW Baima 32 43 26 N / 104 15 58 E H=2640 m, 22.06.2006,  Belousov & Kabak leg."  Paratypes: 2 females with the same data as the holotype and 1 male with the label “CH, S Sichuan, 35km NNW Mianning, NW of Lajiajia upper Anteriorst zone 3400 m, 4.08.2002, Belousov & Kabak leg.”

Description.  Holotype, male (Fig. 7).  Body length 6.8 mm.  Body black, shiny, legs, genal margins and lateral margins of pronotum somewhat reddish-black.  Clypeus rounded, without medial emargination.  Genae feebly distinct, genal and frontoclypeal sutures indistinct.  Eyes very small in dorsal view.  Frons densely and evenly punctate (punctures separated by less than a puncture diameter, sometimes touching).  Clypeus sparsely punctate with minute punctures. 

Pronotum coarsely punctate (punctures separated by 1-2 diameters on disc, becoming denser laterally).  Lateral and basal margins coarsely punctate, posterior angles rounded and not serrate.

Scutellum triangular, impunctate basally, shiny.

Elytra with strong humeral teeth.  Striae deep, punctate (punctures of striae separated by 2-3 puncture diameters; each puncture bears 1 minute yellow seta).  Intervals slightly convex, impunctate.

Anterior tibiae with short lateral teeth; tibial spur slightly curved inward.  Upper spur of hind tibia slightly longer than tarsomere 1, tarsomere 1 shorter than tarsomere 2-4 combined.

Parameres relatively long, their apices rounded in lateral view, with small feebly sclerotized area (Fig. 8).  Internal sac of aedeagus with 3 sclerites one of which is somewhat rounded, with small process (indicated in Fig. 9).

Female.  Distinguished from male by the anterior tibial spur not curved inward and by the more sparsely punctate frons.

Variability.  Body length of paratypes vary from 6.5-7.0 mm, otherwise, except for the sexual dimorphism, they are similar to the holotype.

Differential diagnosis.  Aegialia (Silluvia) igori sp. n. can be separated from other described Silluvia species by the relatively depressed and rounded (in lateral view) apices of parameres and by the shape of internal sac sclerites (Fig. 9).  It is most similar to A. shashi but can be separated from this species by the indistinct frontoclypeal suture and by the clypeus punctate with sparse, minute punctures.  From A. (S.) kabaki and A. (S.) wassuensis,it can be separated by posterior angles of pronotum not serrate.

DistributionAegialia igori sp. n. is known from two localities in Sichuan Province of China (Fig. 13).

Etymology. The species is named after Igor Belousov.

Figs. 7-9.  Aegialia (Silluvia) igori, sp. n., holotype.
Figs. 7-9.  Aegialia (Silluvia) igori, sp. n., holotype.  Fig 7. Habitus  Fig. 8. Aedeagi in dorsal and lateral view.  Fig 9. Internal sacs of aedeagi. Scales: A – refers to Fig 7; B – refers to Figs 8, 9.

 

Aegialia (Silluvia) kabaki Frolov

Figs. 10-13

Material examined.  China, Sichuan Province: WNW of Danba, 6.8 km S of Bianer, H~3485 m, 19.08.2004, Belousov & Kabak leg., 2 males; E Danba S Guanyongchang Vill., H~2990 m, 9.08.2004,  Belousov & Kabak leg., 1 male and 1 female; E of Danba S of Guanyongchang Vill., H~3305 m, 10.08.2004,  Belousov & Kabak leg., 1 male and 1 female; S Rilong, H~3355-3375 m, 27.08.2004, 1 male.

Remark.  Examined specimens show considerable variability in the shape of the pronotum, which vary from rounded in posterior angles (Fig. 10) through excavated in the angles (Fig. 11) to somewhat undulate lateral margins and excavated posterior angles (Fig. 12).  These specimens, however, do not differ in other characters including shape of parameres and internal sac sclerites, (i.e. in characters distinctive for Silluvia species).  I believe these forms are conspecific with the type specimen of A. kabaki, and intermediate forms will be found in future.  Similar and even greater variability of the shape of pronotum is also known in A. (Psammoporus) kamtschatica Motschulsky, 1860, a species widely distributed in the northern Palaearctic Region.

Aegialia kabaki is currently known from a few localities in a relatively small region in Central Sichuan Province (Fig. 13) and may be endemic to this region.

 

Figs. 10-12.  Aegialia (Silluvia) kabaki head and pronotum,
Figs. 10-12.  Aegialia (Silluvia) kabaki head and pronotum, Fig. 10. Specimen from WSW of Lixian.  Fig. 11. Specimen from 6.8 km S of Bianer.  Fig. 12. Specimen from S of Rilong.

 

FIGURE 13. Distribution map of the four species of Silluvia
Fig 13. Distribution map of the four species of Silluvia discussed in this paper.

ACKNOWLEDGMENTS

I am indebted to Igor Belousov and Iliya Kabak (Sankt-Petersburg) who collected and donated the material for this study.  Two anonymous reviewers made valuable comments that considerably improved the draft manuscript.  The work was supported by the grant 07-04-00482-а from the Russian Foundation for Basic Research.

LITERATURE CITED

Dellacasa M. (1988) Contribution to a world-wide Catalogue of Aegialiidae, Aphodiidae, Aulonocnemidae, Termitotrogidae. (Part I).  Memoire della Societа entomologica italiana, 66, 1-455.

Frolov A.V. (2002) A new species of Aegialia from China (Coleoptera: Scarabaeidae).  Coleopterists Bulletin, 56, 308-309.

Petrovitz R. (1963) Neue Aegialinae, Orphninae und Hybosorinae.  Entomologische Arbeiten aus dem Museum G. Frey, 14: 118-125.

Stebnicka Z. (1977) A revision of the world species of the tribe Aegialiini.  Acta Zoologica Cracoviensia, 22, 397-506.

Stebnicka Z. (2006) Scarabaeidae: Aegialiinae. P. 103-104. In: Lцbl I. & Smetana A. (eds): Catalogue of Palaearctic Coleoptera, Vol. 3. Scarabaeoidea – Scirtoidea – Dasciloidea – Buprestoidea – Byrrhoidea.  Apollo Books, Stenstrup, 690 pp.