O VORST1 & M SÖRENSSON2
1National Museum of Natural History, Naturalis, Leiden, The Netherlands 2Lund University, Lund, Sweden
ON THE IDENTITY OF ACROTRICHIS NANA STRAND, A SPECIES DISTINCT FROM A. DISPAR (MATTHEWS) (COLEOPTERA: PTILIIDAE)
Vorst, O. & M. Sörensson, 2005. On the identity of Acrotrichis nana Strand, a species distinct from A. dispar (Matthews) (Coleoptera: Ptiliidae). – Tijdschrift voor Entomologie 148: 329- 333, figs. 1-8. [ 0040-7496]. Published 1 December 2005. Acrotrichis nana Strand, 1946 is reinstated as a proper species distinct from A. dispar (Matthews, 1865) with which it had been previously synonymized. Both species can be reliably separated by primary and secondary sexual characters of the males only. Apart from the single type specimen from southern Norway, A. nana has recently been discovered at two localities in the south of Sweden and in the Netherlands. The availability of extensive material from the latter country, all collected at National Park ‘Veluwezoom’, made the recognition of its true status possible. A large proportion of the specimens were found in association with carcasses of large animals (Highland cattle and wild boar). Oscar Vorst, National Museum of Natural History, Naturalis, PO Box 9517, 2300 RA Leiden, The Netherlands. E-mail: [email protected] Mikael Sörensson, Lund University, Zoology bldg, Helgonav. 3, SE-223 62 Lund, Sweden. E-mail: [email protected] Key words. – Acrotrichis; Ptiliidae; West-Palearctis; carrion; synonymy; featherwing beetles.
Although ptiliid beetles are mostly very small females) of the new species, its true status became in size (0.5 to 1.2 mm), the North and Central evident. Males can easily be separated by primary and European fauna has been extensively studied. Es- secondary sexual characters. No reliable characters pecially the largest and most difficult genus separating the females of both species could be Acrotrichis Motschulsky, 1848 attracted the attention detected. of some skilled coleopterists. As a result several revi- Most material was collected in the course of an ex- sionary studies treating this genus were published tensive study on the entomofauna of large carcasses during the last century (Roßkothen 1934, 1935, carried out at National Park ‘Veluwezoom’ in the Renkonen 1939, Strand 1941, Sundt 1958, 1971, Netherlands. The focus in this study was on Diptera M´lynarski 1984, Sörensson 1988). Many of these and Coleoptera. The latter were collected from sam- publications present accurate figures of male and es- ples taken by sieving the soil impregnated by body pecially female genitalia that are being used as essen- fluids from the carcasses. This habitat proved to be tial characters for the separation of the often similar particularly rich in ptiliid beetles. Twenty-eight sam- species. In addition, the Acrotrichis-fauna of several ples yielded more than 1800 specimens belonging to other geographic regions has been treated in the past 24 different species. These represent almost half of decades (Sundt 1969, Johnson 1969, 1984, 1985, the Dutch ptiliid fauna, which until now comprised 1988, Sawada & Hirowatari 2002). 48 species (Brakman 1966, Huijbregts & Krikken Thus, we were surprised to discover an unknown 1988, Vorst & Huijbregts 2001a, 2001b). A single species of Acrotrichis in Northwest Europe. A single specimen was caught by ‘Autokätscher’ (car net) on male collected in 1988 and another collected in 1997 the Baltic island of Öland while the second Swedish aroused our suspicion, although they first were taken specimen was found in mouldy grass compost. for aberrant specimens of A. dispar (Matthews, 1865). As the newly discovered species is very similar to Only after the recent collection of additional materi- A. dispar, current synonyms of the latter potentially al, including a large unmixed series (10 males and 12 refer to this species. The last world catalogue of
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12 3
45 67
Figs. 1-7. Acrotrichis nana (1-3, 6) and A. dispar (4-5, 7). Aedeagus (1, 4), male visible sternite 6 (= sternite 8) (2, 5), spermatheca (3) and (male) pronotal side-edge (6-7) at an angle of approximately 45°. Scale = 75 µm (figs 1-2, 4-5) or 100 µm (3, 6-7).
Ptiliidae (Csiki 1911) only gives Acrotrichis pumila Collections Thomson, 1862 as a synonym to A. dispar; erro- Natural History Museum, London neously, as Thomson (1862) did not describe this Museum d’Histoire Naturelle, Genève species as new, but just cited the species of that name Nationaal Natuurhistorisch Museum published by Erichson (1845-48) in 1845. Now- Naturalis, Leiden adays, the name pumila Erichson, 1845 is in use as Zoologisk Museum, Oslo the valid name for another Acrotrichis-species. c Collection O. Vorst, Utrecht Two further names have been listed as junior c Collection M. Sörensson, Lund synonyms to A. dispar, viz. Trichopteryx castanea Rey (Rey 1889), recently placed in synonymy with Acrotrichis nana Strand A. dispar by Johnson (2001), and Acrotrichis nana (figs. 1-3, 6) Strand (Strand 1946), previously placed in synonymy by Sundt (1958). Being a junior primary homonym Acrotrichis nana Strand, 1946: 170. Holotype : : ‘Brönnöy Asker / Andr. Strand’, ‘Acrotrichis / nana n.sp. of the Nearctic Trichopteryx castanea Matthews, 1877 the name castanea Rey can not be used as a substitute. / A. Strand / ’ [red] ( ). [examined] According to Strand (1946) the type material of A. nana consists of a single female specimen (holoty- Material examined. – The Netherlands: Terlet, pus). Its spermatheca was illustrated in Strand (1946) Galgenberg, 5.vi.1997, 1 , O. Vorst (c ); Loenen, Loen- ermark, 6.vii.2002, 1 , O. Vorst (c); De Imbosch, Veer- and conforms with the dispar-type. Our study of the tien Bunder, 26.viii.2002, 1 , 29.viii.2002, 1 , type specimen kept at the Zoologisk Museum, Oslo, 30.viii.2002, 1 , 3.ix.2002, 3 , 27.ix.2002, 1 , revealed it as being almost certainly conspecific to the 19.xi.2002, 9 , 4 , J. Newton & L. Joosten (, c); newly discovered species, which should hence be De Imbosch, Veertien Bunder, 14.iii.2003, 4 , O. Vorst named A. nana Strand. In view of the available ma- (c); De Imbosch, Lamsgroen, 9.v.2003, 1 , O. Vorst terial the type specimen is a slightly aberrant and (c ); Groenendaal, 18.iv.2003, 1 , 8.vi.2003, 1 , 11.vii.2003, 1 , 1 , O. Vorst (c); De Imbosch, remarkably small specimen. However, the surface Imboschberg, 11.vii.2003, 2 , 2 , 8.vi.2003, 9 , 7 , O. structure of its thorax makes it distinct from typical Vorst (c, c); Sweden: Skåne (Scania), Ängelholm, A. dispar and underlines its conspecificity with our 6.vi.1978, 1 , M. Sörensson (c); Öland, Böda, recently collected material. 9.vii.1988, 1 , P. Cederström (c).
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glistening head and a mediofrontal pronotum of much reduced puncturation, in such cases making fe- male identifications almost impossible. However, as a rule the remaining pronotal puncturation of A. dispar is more pronounced than in A. nana.
Bionomics All Dutch specimens studied were found in as- sociation with large carcasses of Highland cattle (Bos taurus L.) or wild boar (Sus scrofa L.) in forests on dry sandy soils. A description and photograph of the Highland cattle carcass from which the species was first collected can be found in Vorst & Huijbregts (2001b). During a study of arthropod succession on wild boar carcasses four specimens were captured in a flight interception trap. The first specimen arrived within three days after the time of death (23.viii.2002). Fig. 8. Distribution of Acrotrichis nana Strand. One Swedish specimen was sieved from a mouldy, somewhat warm compost of cut grass situated in a mature plantation of coniferous trees on sandy soil Description close to the North Sea shores of the west coast of the Length 0.66-0.76 mm (from anterior margin of southernmost province of Skåne (Scania). Another labrum to apex of elytra). Very close to Acrotrichis Swedish specimen was caught by ‘Autokätscher’ (car dispar in body shape, size and surface structure. net) driven along a dry pine forest margin in the Aedeagus characteristically shaped with triangular northern part of the Baltic island of Öland, Southeast apex (fig. 1). Visible male sternite 6 (= sternite 8) with Sweden. This lowland forest close to the Baltic sea is a single group of about 25 setae (fig. 2). Spermatheca situated in one of the driest and warmest areas of as in figure 3. Sweden.
Differential diagnosis Distribution Externally very similar to Acrotrichis dispar. Males See fig. 8. So far only known from the Norwegian can easily be separated by the shape of the aedeagus, type locality (near Oslo), two distant sites in which has a simple triangular apex opposed to a tri- South and Southeast Sweden and the National partite apex in A. dispar (figs. 1, 4), and the character- Park ‘Veluwezoom’, province of Gelderland, The istic group of setae on visible sternite 6 (= sternite 8) Netherlands, but doubtless overlooked and much which differs both in extent and configuration wider distributed. However, checking of more than (figs. 2, 5). The female spermathecae are seemingly one hundred specimens of A. dispar from various lo- identical. calities in Switzerland preserved in did not External differences are only slight and subject to yield any more A. nana (Sörensson pers. obs.). variation. Generally speaking, the upper surface of A. nana is more shiny, due to less strong puncturation Discussion and microreticulation. This difference is most promi- In view of the current knowledge of the genus nent on the head and the front of the pronotum, Acrotrichis in Northwest Europe it seems rather sur- where the stippled puncturation and microreticula- prising that the specific status of A. nana has been tion shows the strongest reduction. The side margins overlooked for almost fifty years. It suggests that of the pronotum are on average more curved than in Acrotrichis nana is either rarely collected or recently A. dispar and provided with a more obvious marginal (re)introduced. At least in the Netherlands (and bead, probably due to its often contrastingly paler Scandinavia) it is nowadays much rarer than the sim- colour as compared to the remainder of the prono- ilar A. dispar. The latter was seen from 30 localities tum. The pronotum is a trifle smaller and slightly (73 males in total) throughout the Netherlands as more domed (convex). well as from an additional number of sites from South As the intraspecific variation of the external surface and Central Sweden. The apparent rareness of sculpture of A. dispar is considerable, care should A. nana might possibly be explained by a preference be taken when identifying females. There are odd for a specific biocoenosis or source of nutrition, like specimens of A. dispar showing an almost equally (larger) carcasses. The ecological preferences of
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A. dispar are much wider and it can be found in asso- genitalic characters. In addition, it is probably con- ciation with all kinds of decaying organic matter. specific with specimens from the same area inciden- Apart from the type specimen, which was collected tally seen in the Natural History Museum, London, in 1944, no older material (before 1997 in the standing under the manuscript name ‘disparoides Netherlands and 1978 in Sweden) could be traced. Sundt’, a name never published. Further study of this A recent (re)introduction of Acrotrichis nana can not material is required in order to establish the possible be excluded. As a matter of fact, several nowadays conspecificity. widespread Acrotrichis-species did colonise Northwest Europe only in the recent past: Acrotrichis insularis A (Mäklin, 1852) (Johnson 1966), A. cognata (Matthews, 1877) (Easton 1967) and A. henrici We would like to thank J. Huijbregts, Th. Heijer- (Matthews, 1872) (Johnson 1967); see Sörensson & man, and especially J. Newton and L. Joosten who Johnson (2004) for a comprehensive overview of the collected part of the material during a study on the invasive ptiliid species of Europe. Whatever may be entomofauna of wild boar carcasses; A. ten Hoedt, the case, Acrotrichis nana will without any doubt J. Potkamp and H. van Dijk of Vereniging Natuur- prove to have a wider European distribution than monumenten for giving permission to study the known at present. beetle fauna at ‘Veluwezoom’ and providing assis- tance afield; P. Cederström for permission to study This ‘new’ species of the large, panglobal ‘mega- his vast and interesting Swedish ptiliid material; genus’ Acrotrichis belongs to a certain section which K. Sund () for the loan of type material; comprises smaller, more or less parallel-sized species C. Besuchet (); S. Shute () and with lightly coloured, rather thin and small sperma- R. Danielsson (Zoological Museum of Lund) for thecae of special configuration (vide Sundt 1958, kindly permitting the study of their museum 1971). In Europe, this species group – here informal- collections. ly termed the ‘dispar-group’ (= ‘brevipennis-group’ sensu Sundt 1969: 49) – tentatively comprises R A. dispar and A. nana, possibly also A. pumila (Erichson) and A. brevipennis (Erichson, 1845). This Brakman, P. J., 1966. Lijst van Coleoptera uit Nederland is a more restricted arrangement as compared to the en het omliggend gebied. – Monographieën van de Nederlandsche Entomologische Vereeniging 2: i-x, 1-219. broad and heterogeneous ‘sericans-group’ of Sawada Csiki, E., 1911. Fam. Ptiliidae. – Coleopterorum Catalogus & Hirowatari (2002) which includes A. sericans (Heer, 32: 5-61. 1841) and A. pumila as well as other more distantly re- Easton, A. M., 1967. The Coleoptera of a dead fox (Vulpes lated species. Although Acrotrichis sericans, indeed, vulpes (L.)); including two species new to Britain. – Ento- might be closely related to A. dispar, Japanese species mologist’s Monthly Magazine 102: 205-210. other than A. sericans and possibly A. meridiana Erichson, W. F., 1845-48. Naturgeschichte der Insecten Deutschlands. Erste Abtheilung Coleoptera. Dritter Sawada & Hirowatari, 2002 should be excluded from Band. – Verlag der Nicolaischen Buchhandlung, Berlin. the sericans-group due to various diagnostic discrep- vii + 968 pp, 1 pl. ancies of certain morphological and genital charac- Huijbregts, J. & J. Krikken, 1988. Aanvullingen op de lijst ters. For the time being, and viewed on a world scale, van Nederlandse kevers (1985-1986). – Nieuwsbrief it seems most practical to keep A. sericans and European Invertebrate Survey - Nederland 18: 7-8. A. dispar and its relatives apart in different species Johnson, C., 1966. Two species of Acrotrichis new to Britain (Col., Ptiliidae). – Entomologist 99: 152-154. groups until more data have accumulated. Johnson, C., 1967. A revised and annotated British list of The junior author has studied further species from Acrotrichis (Col., Ptiliidae). – The Entomologist 100: other parts of the world obviously belonging to the 132-136. ‘dispar-group’ and the ‘sericans-group’. Undescribed Johnson, C., 1969. The genus Acrotrichis Motschulsky species (including the sister species of A. dispar) ex- (Coleoptera: Ptiliidae) in the Ethiopian Region. – Revue tremely closely related to A. dispar and A. nana and de Zoologie et de Botanique Africaines 79: 213-260, pl 1-7. Johnson, C., 1984. New data on Afrotropical Acrotrichis possessing similar genitalia occur in North America Motschulsky with description of seven new species (Sörensson in prep.). Other undescribed species (Coleoptera, Ptiliidae). – Revue de Zoologie Africaine 98: closely related to A. sericans occur in North America, 197-210. the Neotropical and the Oriental region. No Ethiopi- Johnson, C., 1985. Revision of Ptiliidae (Coleoptera) occur- an species belonging to any of the groups mentioned ring in the Mascarenes, Seychells and neighbouring is- are known at present. lands. – Entomologica Basiliensia 10: 159-237. Of special interest in this context is a single female Johnson, C., 1988. Revision of Sri Lankan Acrotrichines (Coleoptera: Ptiliidae). – Revue Suisse de Zoologie 95: specimen from Nepal (c ) which hardly can be 257-275. distinguished from A. nana based on external and
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Johnson, C., 2001. Notes on Palaearctic Ptiliidae Strand, A., 1946. Seven new species of Coleoptera from (Coleoptera). – Entomologist’s Gazette 52: 129-137. Norway. – Norsk Entomologisk Tidskrift 7: 168-172. M´lynarski, J. K., 1984. Materials to the revision of the Sundt, E., 1958. Revision of the Fenno-Scandian species of genus Acrotrichis Motschulsky, 1848 (Coleoptera, the genus Acrotrichis Motsch., 1848. – Norsk Entomolo- Ptiliidae) [in Polish]. – Acta Zoologica Cracoviensia 27: gisk Tidsskrift 10: 241-277, pl 1-4. 305-376. Sundt, E., 1969. Description of a new subgenus, Flachiana, Renkonen, O., 1939. Über die finnischen Arten der Gat- and four new species of the genus Acrotrichis Motschul- tung Acrotrichis Motsch. (Col., Ptiliidae). – Suomen sky, 1848 (Col., Ptiliidae). – Norsk Entomologisk Hyönteistieteellinen Aikakauskirja 5: 177-207. Tidskrift 16: 49-53. Rey, C., 1889. Remarques en passant, Famille des Sundt, E., 1971. Acrotrichis. – In: Freude, H., K. W. Harde, Trychopterygides. – Échange, Revue Linnéenne 5(50): 4. & G. A. Lohse (eds). Die Käfer Mitteleuropas, Band 3: Roßkothen, P., 1934. Zur Kenntnis der deutschen 335-342. Goecke & Evers, Krefeld. Acrotrichis-Arten. – Entomologische Blätter für Biologie Thomson, C. G., 1862. Skandinaviens Coleoptera, synop- und Systematik der Käfer 30: 113-116, pl 1-2. tiskt bearbetade, Tom 4. – Lundbergska Boktryckeriet, Roßkothen, P., 1935. Bestimmungstabelle der deutschen Lund. 269 pp. Acrotrichis-Arten. – Entomologische Blätter für Biologie Vorst, O. & J. Huijbregts, 2001a. Overzicht van de und Systematik der Käfer 31: 165-172. wijzigingen in de lijst van Nederlandse kevers (1987- Sawada, Y. & T. Hirowatari, 2002. A revision of the genus 1999) (Coleoptera). – Entomologische Berichten 61: Acrotrichis Motschulsky (Coleoptera: Ptiliidae) in Japan. 80-88. – Entomological Science 5: 77-101. Vorst, O. & J. Huijbregts, 2001b. Drie ptiliiden van run- Sörensson, M., 1988. Studies of Danish Ptiliidae derkadavers nieuw voor de Nederlandse fauna (Coleoptera). – Entomologiske Meddelelser 56: 35-48. (Coleoptera: Ptiliidae). – Entomologische Berichten 61: Sörensson, M. & C. Johnson, 2004. The first European 133-141. records of the pantropical genus Bambara Vuillet, and a review of the immigrant featherwing beetles in Europe (Coleoptera: Ptiliidae). – Koleopterologische Rundschau 74: 287-302. Strand, A., 1941. Die norwegischen Arten der Gattung Acrotrichis Motsch. (Col. Ptiliidae). – Norsk Entomolo- Received: 3 October 2004 gisk Tidsskrift 6: 25-30. Accepted: 19 April 2005
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