Chilamblyopinus piceus, a New Genus and Species of Amblyopinine (Coleoptera: Staphylinidae) from Southern Chile, with a Discussion of Amblyopinine Generic Relationships

Taxonomic history of staphylinid beetles of the tribe Amblyopinini is dis cussed. Chilamblyopinus piceus, a distinctive new genus and species, is described and illustrations of diagnostic characters are provided. A key to currently recognized genera in the Amblyopinini is provided. A preliminary reevaluation of relationships among genera currently included in the Amblyopinini suggests that substantial changes in the classification may be required. Myotyphlus, which occurs in the Australian region, shares derived char acters both with some members of the genus Quedius, which occur in the Australian region and with the amblyopinine genus Edrabius, which occurs in the Neotropics, as do all other amblyopinines. The monophyly of the lineage which includes these two genera is uncertain. Few characters other than structural reductions and association with mammalian hosts suggest that Myotyphlus and Edrabius are a part of a monophyletic lineage with other South American amblyopinines. In contrast, Amblyopinodes, Amblyopinus, Chilambly opinus, and Megamblyopinus form a well supported monophyletic lineage of strictly South and Central American taxa. Chilamblyopinus appears to be the most basally derived. Megamblyopinus is a sister group to Amblyopinodes and Amblyopinus. Amblyopinodes is highly autapomorphic; however, Amblyopinus cannot be shown to be monophyletic, and may be a paraphyletic taxon in relation to Amblyopinodes. Additional characters and a more firmly established outgroup for the Amblyopinini as a whole are required for reso lution of these problems. Beetles of the tribe Amblyopinini are unique among staphylinids, and unusual among all Coleoptera, because of their apparently obligate association with small mammals. Adult amblyopinines are almost always collected from the fur of their mammalian hosts and, until recently, were believed to be obligate, blood-feeding ectoparasites (Seevers, 1955; Askew, 1971; Kim and Adler, 1985). Recently, we have shown that at least some members of the genus Amblyopinus are not ecto parasitic, but instead are predators on ectoparasites of their hosts (Ashe and Timm, 1987a, b). Habits of members of other genera are unknown; however, all ambly opinines are characterized by profound structural modifications, presumably in response to life in association with their mammalian hosts (see Seevers, 1955). The unusual structural and behavioral features of amblyopinines have resulted in a taxonomic history of the group characterized by considerable confusion. Opinions about both the taxonomic affinities of amblyopinines within the Staphy linidae and the genera which should be included as amblyopinines have varied substantially over the last 100 years. Amblyopinine staphylinid beetles were first described and characterized by Solsky (1875) who recognized a single genus Amblyopinus based on two species, 1 Department of Zoology, Field Museum of Natural History, Chicago, Illinois 60605. 2 Museum of Natural History and Department of Systematics and Ecology, University of Kansas, Lawrence, Kansas 66045. Accepted for publication 26 August 1987. VOLUME 61, NUMBER 1 47 A. jelskii and A. mniszechi. He believed this genus to be a member of the "tribe" "Tachyporiens", and was intrigued by the account of Mr. C. Jelsky, the collector, regarding apparently obligate ectoparasitic relationships between members of Am blyopinus and mammals in the Peruvian Andes. Later, Matthews (1878) described a new species, Amblyopinus jansoni, from "the fur of a living Rat" (p. 275) in Tasmania. He believed that this species was correctly placed in the genus Am blyopinus as described by Solsky and felt that revision of the taxonomic position of the genus was warranted. The new species from Tasmania appeared to be much more closely related to Philonthus and Quedius (tribe Staphylinini) than to tachy porine staphylinids. Fauvel (1883) noted that Solsky's Amblyopinus and Matthews' species from Tasmania were actually very different. Fauvel believed that Amblyopinus in the sense of Solsky was indeed a tachyporine near the genus Habrocerus. In contrast, the Tasmanian species was in the tribe Staphylinini near the genera Quedius and Heterothops. He therefore proposed the new generic name Myotyphlus for the Tasmanian species, Amblyopinus jansoni Matthews. Matthews (1884) felt that "the name proposed by M. Fauvel, 'Myotyphlus,' Anglice, 'a blind mouse,' does not seem peculiarly applicable to a Coleopterous insect with distinct and ser viceable eyes" (p. 87). Since Fauvel did not provide a generic description of Myotyphlus, Matthews proposed the generic name Cryptommatus for the Tas manian A. jansoni. However, Fauvel's name Myotyphlus has priority based on the original species description and is the second of the currently recognized amblyopinine genera to be described, although it was not believed to be an am blyopinine at the time. In 1900 Fauvel described the genus Edrabius based on the species E. philippianus from specimens collected from Ctenomys in Chile. Fauvel apparently believed that Edrabius was closely related to Amblyopinus. Little changed in the taxonomy of amblyopinines until 1944 when Seevers published the first of two important papers on the group (Seevers, 1944, 1955). Seevers (1944) did not describe any new genera; however, he did recognize that Amblyopinus and Edrabius were not correctly placed near Habrocerus (which was by that time placed in the subfamily Habrocerinae). He consequently suggested that these two genera occupy an isolated position within the Staphylinidae and proposed the subfamily Amblyopininae to contain them. He clearly intended the new subfamily to include both Amblyopinus and Edrabius but did not mention Edrabius in the subsequent treatment of the subfamily. He also did not include Myotyphlus among amblyopinines at that time. In 1955 Seevers published a major revision of the amblyopinines in which he proposed that the group was closely related to the staphylinine tribe Quediini, from which he believed them to be separate based on their specialized ectoparasitic habits. In this revision he included both Myotyphlus and Edrabius together with Amblyopinus in the tribe Amblyopinini and described two new genera based on distinctive groups of species which previously had been placed in Amblyopinus. He included those species which were characterized by a highly derived head capsule and the presence of black, claviform setae on the sternites in the genus Amblyopinodes (type species A. gahani Fauvel). He included large species with more generalized head capsules in the genus Megamblyopinus (type species A. mniszechi Solsky). There has been no substantial modification to the generic level classification of 48 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY the Amblyopinini since Seevers' (1955) revision. Although numerous new species have been described, no undescribed genera have been discovered. Thus, the discovery of a morphologically distinctive new genus-level taxon is particularly exciting. Our studies, which were prompted by the discovery of this new genus, required a reexamination of generic level taxa of the Amblyopinini and their relationships. Though this investigation is still in an early stage, the preliminary results suggest that substantial modification to the genus-level classification of amblyopinines may ultimately be required. In this paper we describe a new genus and species of amblyopinine staphylinid from Chile, provide a key for distinguishing the currently recognized genera of the Amblyopinini, and outline the preliminary results of our studies on the re lationships among amblyopinine genera. Key to the Genera of the Tribe Amblyopinini Herein we present a key to all known genera of the tribe Amblyopinini. Some characters used in this key have been used previously in keys to genera of the Amblyopinini (Seevers, 1955; Machado-Allison, 1963; Coiffait and Saiz, 1968). However, reexamination of members of all genera, and discovery of the new genus described here, have led to reevaluation of previously used characters and dis covery of new characters for more reliable separation of genera. 1. Eyes minute, single faceted, located immediately posterior to antennal fossae and distant from basal angles of head; gular sutures subparallel for most of their lengths (see Seevers, 1955, fig. 32a, c) . 2 Eyes larger, multifaceted, distant from antennal fossae and located im mediately anterior to basal angles of head; gular sutures subparallel only medially and broadly divergent both anteriorly and posteriorly (see Seevers, 1955, fig. 32b, d, e) . 3 2. Tarsomere I of mesothoracic legs with distinct comb of short, dark spines extending almost entire length of article; lateral plates of abdominal segment IX with scattered unmodified macrosetae; Australia and Tas mania .Myotyphlus Fauvel Tarsomere I of mesothoracic legs without comb of short, dark spines; each lateral plate of abdominal segment IX with apical patch of ex tremely long aciculate setae in addition to scattered unmodified mac rosetae; South America.Edrabius Fauvel 3. Large, 13 mm or greater in length; elytra as long as or longer than broad; hind coxae relatively generalized, more or less triangular; labrum large, deeply bilobed, clearly visible from above . 4 Smaller, 11 mm or less in length; elytra broader than long; coxae more specialized, more or less oval or transverse, not triangular; labrum small, slightly bilobed, not, or at most only slightly, visible from above . 5 4. Body more or less parallel sided; pronotum more or less parallel sided, apex only slightly narrower than base; anterior tibia broadly dilated and flattened distally with distinct lateral spines; pronotum with only numerous small asetose punctures (except for marginal macrosetose pores); abdominal terga with 1-3 marginal macrosetae. .Megamblyopinus Seevers VOLUME 61, NUMBER 1 49 Body fusiform, broadest at base of pronotum and elytra (Fig. 1); pronotum distinctly broader at base than apex; anterior tibia not distinctly dilated and flattened distally, without distinct lateral spines; pronotum with two distinct, more or less uniformly distributed, puncture types, con sisting of larger punctures containing small to moderate macrosetae, and much more numerous and smaller asetose punctures; abdominal terga with numerous macrosetae laterally on both the disc and the margins. Chilamblyopinus, new genus 5. Abdominal sterna III-V, or III-VI, with marginal black claviform setae; clypeus markedly deflexed, labrum not visible from above . .Amblyopinodes Seevers Abdominal sterna without marginal black claviform setae; clypeus not or at most slightly deflexed, labrum slightly visible from above.