Great Smoky Mountains National Park (GSMNP) includes an area of ca. 2,200 square kilometers in the southern Appalachian Mountains in the states of North Carolina and Tennessee. The park is known for its extraordinarily rich species diversity. For example, there are more than 1,700 species of vascular plants including more native trees (130 species) than in all of Europe. The park is the home of 61 native mammals, 340 birds, 84 reptiles, nearly 50 amphibians, and over 50 fish species. It also hosts a diversity of invertebrates, especially arthropods. However, many groups of these small creatures are little known and understudied. To change the situation and to better understand and catalogue the biodiversity of GSMNP, in early 1990, dozens of scientists and trained volunteers participated in a large project, called the All Taxa Biodiversity Inventory (ATBI) (Sharkey 2001). For Collembola, Bernard & Felderhoff (2007) estimated a total of 220 species were present based on previous records and recent numerous collections, with many of the taxa being undescribed.

Among a world fauna of Collembola, the subfamily Neanurinae are the most species rich and defined by the characteristic arrangement and number of sensilla on the 4th antennal segment (Deharveng 1983). Additionally, most Neanurinae are characterized by strongly developed cuticular tubercles on the dorsal surface of the body. Although nearly 800 species of Neanurinae have been described, there are many geographical regions, including the southeastern USA, where the knowledge of this subfamily is still far from complete.

Analysis of rich materials of Collembola from GSMNP revealed a new species of Neanurini. This tribe includes more than 170 species belonging to 23 genera (Cassagnau 1989; Hopkin 1997, Deharveng & Bedos 2000; Deharveng et al. 2007; Smolis 2007, 2011; Mayvan et al. 2015; Bellinger et al. 2017). A new species from GSMNP exhibits unique features that easily separate it from other Neanurini and support the establishment of a new monobasic genus. Its description and taxonomic remarks are presented below.

Materials and Methods

The specimens were cleared in Nesbitt's fluid, subsequently mounted on slides in Swan's medium and studied with a Nikon Eclipse E600 (Nikon Instruments Inc., Amsterdam, the Netherlands) phase contrast microscope. Figures 1–14 were drawn with the aid of a camera lucida and prepared for publication using Adobe Photoshop CS3 (Adobe Systems Inc., San Jose, California, USA). The map (Fig. 15) was created using “Royalty free clip art maps” provided by  www.freeusandworldmaps.com (accessed 21 June 2017).

Terminology and abbreviations for the description are used following Deharveng & Weiner (1984), Smolis & Deharveng (2006), Palacios-Vargas & Simón Benito (2007), and Smolis (2008).

Figs. 1–14.

Intricatonura fjellbergi sp. nov. 1) Chaetotaxy of head, thorax and Abd. I, dorsal view of holotype; 2) Chaetotaxy of labium and Vi-group setae; 3) Labrum; 4) Mandible; 5) Maxilla; 6) Chaetotaxy of ant. III–IV, ventral view; 7) Apical vesicle, dorsal view; 8) Chaetotaxy of antennal segments III–IV, dorsal view; 9) Chaetotaxy of lateral part of head, dorsal view; 10) Chaetotaxy of lateral part of head, ventral view; 11) Chaetotaxy of Abd. III–V, dorsal view; 12) Chaetotaxy of Abd. II–V, ventral view; 13) Seta s of abdomen V; 14) seta Di1 of Abd. V.

Fig. 15.

Generic diversity of Neanurini and the number of genera in 4 zoogeographical regions.

Abbreviations used:

General morphology: Abd. — abdomen, Ant. — antenna, AOIII — sensory organ of antennal segment III, Th. — thorax, VT — ventral tube.

Groups of setae: Ag — antegenital, An — setae of anal lobes, ap — apical, ca — centroapical, cm — centromedial, cp — centroposterior, d — dorsal, Fu — furcal, vc — ventrocentral, Ve or ve — ventroexternal, Vea — ventroexternoanterior, Vem — ventroexternomedial, Vep — ventroexteroposterior, Vel — ventroexternolateral, Vec — ventroexternocentral, Vei — ventroexternointernal, Vi or vi — ventrointernal, Vl — ventrolateral.

Tubercles and groups of chaetae: Af — antenno—frontal, Cl — clypeal, De — dorsoexternal, Di — dorsointernal, DL — dorsolateral, L — lateral, Oc — ocular, So — subocular.

Types of setae: Ml — long macroseta, Mc — short macroseta, Mcc — very short macroseta, me — mesoseta, mi — microseta, ms — s — microseta, S — seta s, bs — S — seta on Ant. IV, miA — microsetae on Ant. IV, iv — ordinary setae on ventral Ant. IV, or — organite of Ant. IV, brs — border S — seta on Ant. IV, i — ordinary seta on Ant. IV, mo — cylindrical S — setae on Ant. IV (soies mousses), x — labial papilla x, L' — ordinary lateral seta on Abd. V.

Depositories: USNM — National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia; DIBEC — Department of Invertebrate Biology, Evolution and Conservation, Institute of Environmental Biology, University of Wrocław, Poland.

Results

Table 1.

Cephalic chaetotaxy of Intricatonura fjellbergi gen. nov., sp. nov.

In order to assign the new genus within the tribe Neanurini, we modified the key published by Mayvan et al. (2015) as follows:

Table 2.

Postcephalic tergal tubercle chaetotaxy of Intricatonura fjellbergi gen. nov., sp. nov.

Table 3.

Distribution of genera of Neanurini in zoogeographic regions.

Discussion

Within subfamily Neanurinae, the tribe Neanurini is of special interest because of its distribution and high diversity. With the exception of 2 species, Neanura muscorum Templeton and Deutonura gibbosa Porco et al. that have been become distributed worldwide presumably by human activities, all members of the tribe are exclusively found in Laurasia (Deharveng et al. 2015). The distribution of genera belonging to this tribe is provided in Table 3 and Fig. 15. Whereas Neanurini are fairly widespread and widely distributed, from western Europe to the southeastern USA, and from the Arctic to North Africa and Vietnam (e.g., Fjellberg 1985; Jordana et. al 1997; Babenko & Fjellberg 2006; Deharveng et al. 2015), almost all known genera appear to be very localized and restricted to narrow zoogeographic regions. Among 24 genera, only Deutonura and Endonura are Holarctic and reported from both the Palaearctic (Western and Eastern) and Nearctic. The other 20 taxa are restricted to 1 of 4 regions (Table 3, Fig. 15). The largest generic and species diversity of Neanurini occurs in the Western Palaearctic where currently 18 genera and 145 species are known. Thus, in this region Neanurini constitutes more than 80% of all genera and species of Neanurinae. For comparison, in areas of the eastern Palaearctic and Nearctic that are comparatively well-studied (Rusek & Marshall 1995; Deharveng & Weiner 1984), this tribe usually constitutes less than 25% of overall Neanurinae diversity. One of explanations of the observed picture and notably high generic and species richness of the tribe in the Western Palaearctic could be low diversity and, in consequence, lack or low degree of competition of other Neanurinae tribes. These tribes are represented in the mentioned zoogeographic region only by a single native species (Paranurini, Sensillanurini), a single introduced 1 (Lobellini), and a few genera with relatively small number of species (Paleonurini). In contrast to the Western Palaearctic, these tribes dominate or co-dominate, and have numerous native genera and species in the Eastern Palaearctic (Paranurini, Lobellini, Paleonurini), Oriental (Paranurini, Lobellini, Paleonurini) and Naearctic (Paranurini, Sensillanurini). It should be mentioned, however, that boreal areas of Holarctic, generally very poor in species of the subfamily, do not show the mentioned pattern in distribution of the tribe.

In spite of the apparently low diversity of Neanurini in the Nearctic, Eastern Palaearctic, Oriental and Australasian, knowledge of the tribe in these regions can be crucial in the context of its history and relationships between genera. We believe also that molecular analyses based on extensive materials of this new genus and species could help the solution of some “intricate” problems connected with its unclear systematic and taxonomic position.