Afroprinus cavicola gen. et sp. n. from the Afrotropical region with notes on cave-dwelling Saprininae (Coleoptera, Histeridae)

Abstract A new genus and species from Kenya, Afroprinus cavicola is herein described and illustrated and its systematic position is discussed. By the prosternal pre-apical foveae connected by marginal prosternal stria it resembles most of the Afrotropical species of the genus Chalcionellus Reichardt, 1932, or some species of the genus Pholioxenus Reichardt, 1932 from South Africa and Namibia. Afroprinus can be distinguished from Chalcionellus chiefly by the lack of pronotal depressions and a coarsely sculptured, non-metallic dorsum; from Afrotropical species of Pholioxenus it can be most easily distinguished by the asetose pronotal hypomeron. The new taxon was discovered in a cave, but lacks obvious troglophilic adaptations. Notes on other Saprininae taxa found in caves are given. An identification key to the genera of Afrotropical Saprininae is provided.


introduction
The Saprininae of the Afrotropical Region are quite well known and have been studied for many years, and except for descriptions of genera or species scattered in the entomological literature of the past 180 years there are several generic revisions (e.g. Gomy and Vienna 1996), as well as many studies on the histerid fauna of particular countries that also contain data on the Saprininae. Such country studies (in most cases called 'Contributions to the knowledge') were mostly published by Gomy (see e.g. Gomy 1978Gomy , 1983Gomy or 1986), but also by other authors (e.g. Desbordes 1930 or Penati and Vienna 1996). Despite this, there is still no systematic revision of the Afrotropical Saprininae, or a catalogue to deal specifically with this region. According to the recent world catalogue of Mazur (2011) there are 22 genera and 199 species of Saprininae occurring in the Afrotropical region. However, it is probable that such a large tropical area must house much larger diversity of the Saprininae than the taxonomic literature indicates.
During a visit to the Natural History Museum, London, UK in 2009 I have examined a series of apparently unknown Saprininae specimens, identified as Gnathoncus sp. After having performed a phylogenetic analysis of the Saprininae subfamily (Lackner, unpublished), I can conclude that this is an unknown taxon belonging to a new genus. The prosternal pre-apical foveae connected by the marginal prosternal stria found in this taxon is a rare feature among the Old World Saprininae and it is more likely to be found among the members of Euspilotus Lewis, 1907, common to the Neotropical region (Lackner, pers. observ.). However, in the Afrotropical region there are Saprininae that have the prosternal pre-apical foveae connected by the marginal prosternal stria. These taxa are found among ill-defined and most likely polyphyletic genera Chalcionellus Reichardt, 1932 andPholioxenus Reichardt, 1932. Revisions of both afore-mentioned genera are badly needed.
In this contribution to the systematics and taxonomy of the Saprininae a new genus and its type species are described and the systematic position of the new genus in the Saprininae subfamily is discussed. A tentative key to the genera of the Afrotropical Saprininae is provided.

Material and methods
All dry-mounted specimens were relaxed in warm water for several hours or overnight, depending on the body size. After removal from original cards, the beetles were sidemounted on triangular points and observed under a Nikon 102 stereoscopic microscope with diffused light. Some structures were studied using methods described by Ôhara (1994): the head and male genitalia were macerated in a hot 10% KOH solution for about 15 minutes, cleared in 80% alcohol, macerated in lactic acid with fuchsine, incubated at 60ºC for two hours, and subsequently transferred into a mixture of glacial acetic acid 1 part and methyl salicylate 1 part heated at 60ºC for 15 minutes and cleared in xylene. Specimens were then observed in α-terpineol in a small glass dish. dorsal view is visible along its entire length. By the convex apical third of the prosternal process and by the prosternal pre-apical foveae connected by the marginal prosternal stria Afroprinus can also be confused with several Afrotropical species of the genera Chalcionellus or Pholioxenus. It differs from those species of Chalcionellus that have the prosternal pre-apical foveae connected by the marginal prosternal stria by the sculpture of dorsal surface, which is metallic and much coarser in Afroprinus and by lacking the pronotal depressions of Chalcionellus. From those species of Afrotropical Pholioxenus (mainly from South Africa and Namibia) that likewise have their prosternal pre-apical foveae connected by marginal prosternal stria, Afroprinus differs by the asetose pronotal hypomeron and much coarser and denser elytral punctuation.
Biology. The type series of Afroprinus cavicola has been found on bat droppings in a Kenyan cave.
Distribution. Kenya. Etymology. The generic name is a combination of the genus name 'Saprinus' with a prefix derived from the continent of Africa. Gender masculine. Antennal scape ( Fig. 4) with several short setae; antennal club (Figs 3,14) round, without visible articulation, somewhat flattened dorso-ventrally; approximately distal half of its surface with thick short sensilla; proximal half with imbricate microsculpture, sensilla absent; sensory structures of antennal club (Fig. 14) with tiny sensory area accompanied by a tiny stipe-shaped vesicle on internal distal margin of antennal club.
Mouthparts. Mandibles ( Fig. 12) with rounded outer margin strongly curved inwardly, apically pointed; sub-apical tooth on inner margin of left mandible large, al-   Fig. 13) convex, labral pits each with two setae; terminal labial palpomere elongate, four times as long as broad; cardo of maxilla with several short setae, stipes triangular, with three long setae; mentum quadrate, anterior margin with deep median notch, anterior and lateral margins with a row of sparse short ramose setae, disc of mentum with several short setae; terminal maxillary palpomere ( Fig. 5) elongate, five times as long as broad, approximately 2.5 times as long as penultimate palpomere.
Elytra: epipleuron with fine scattered punctures; marginal epipleural stria complete; marginal stria straight, well impressed, carinate, continued as intermittent apical stria. Humeral stria well impressed on basal third, somewhat obliterated by coarse punctuation; inner subhumeral stria well developed, visible as long median fragment posteriorly nearly reaching first dorsal stria; with carinate dorsal striae 1-4 (some specimens with a vague fragment of fifth stria on fourth elytral interval); striae 1-3 sub-equal in length, posteriorly reaching approximately five-sixths of elytral length, fourth dorsal stria slightly shorter, anteriorly well-connected with carinate sutural stria; sutural stria straight, well impressed, posteriorly connected with fragmented apical stria; between sutural stria and suture with row of microscopic punctures. Entire surface coarsely and densely punctate, punctures separated by spaces sub-equal to their diameter or shorter, periscutellar area with slightly sparser punctuation; interspaces with isodiametric microsculpture. Propygidium ( Fig. 7) completely exposed, its punctuation similar to that on elytra and pygidium.
Intercoxal disc of metaventrite slightly convex, entirely covered with scattered fine punctures separated by spaces 2-3 times as wide as their diameter, anteriorly punctures becoming coarser and denser, in male more so; lateral metaventral stria ( Fig.  10) straight, carinate, almost reaching metacoxa; lateral disc of metaventrite slightly impressed, with deep round punctures; metepisternum + fused metepimeron with distinctly denser punctures; marginal metepisternal stria complete, deeply impressed.
Intercoxal disc of first abdominal sternite with complete lateral striae, disc with scattered fine punctures, separated spaces as wide as 3 times puncture diameter.  Protibia (Fig. 11) slightly dilated; outer margin with 6 short teeth, each topped by short rounded denticle gradually reducing in size towards base of tibia, followed by a minute denticle; setae of outer row sparse, short; setae of median row even shorter; pro-tarsal groove deep; anterior protibial stria carinate, shortened apically; protibial spur minuscule, approximate to tarsal insertion; outer part of posterior surface of protibia smooth, demarcated from median part by distinct straight line; posterior protibial stria complete, terminating in two inner posterior denticles, separating median part of posterior surface from smooth inner part of posterior surface; inner margin of protibia with dense row of lamellate setae that gradually increase in size towards tibial apex. Mesotibia (Fig. 6) slender, outer margin with a single row of short denticles gradually increasing in size towards tibial apex; setae of outer row moderately long, sparse, lightly sclerotized; setae of median row much thinner and sparser; posterior stria almost complete and only slightly shortened distally; anterior surface with a row of short denticles on outer margin, surface otherwise smooth; anterior stria complete; apical spur short; apical margin of with several stout denticles; claws of terminal tarsomere slightly bent, shorter than half tarsomere length. Metatibia ( Fig. 9) more slender than mesotibia, its denticles sparser than those of mesotibia, otherwise similar to it.
Etymology. The specific epithet was derived using a compounding method of word formation, by stringing together Latin word 'caverna' meaning cave and combining element of Latin origin '-cola' (orig. colo, ere to inhabit) meaning inhabitant, referring to the cavernicolous habitat of this new species. 'Cavicola' is a noun in apposition, which is in accordance with ICZN rules; Article 11.9.1.2

Key to identification of Afrotropical genera of Saprininae
This key is preliminary and in future will be revised, especially in regard to the ill-defined and heterogeneous genera Saprinus, Hypocacculus, Chalcionellus and Pholioxenus. Pholioxenus shows a discontinuous distribution, with about two-thirds of its species living nidiculously inside burrows and faecal chambers of small ground mammals in the Palaearctic region and one-third found free-living in South Africa, Namibia etc., with a single species of unknown biology (P. trichoides Kapler, 1992) described from north Sudan (Mazur 2011). Revision of the genus Pholioxenus is in preparation (Lackner, manuscript). Subgenera, with exceptions of Hesperosaprinus and Neosaprinus of the Nearctic and mainly Neotropical genus Euspilotus which are pertinent to this key, are excluded, since they fall within the limits of their respective genera. Limits of the Afrotropical region are according to Löbl and Smetana (2004)  Prosternum setose, elytral epipleuron setose, marginal elytral stria single 4 (5) Lateral metaventral stria reaching metepisternum; all dorsal elytral striae 1-4 well developed; carinal prosternal striae strongly approximate, weak (absent in some specimens); lateral prosternal striae anteriorly joined by marginal prosternal stria (Fig. 22)  Prosternal pre-apical foveae present (Fig. 8)

Discussion
In the recently performed phylogenetic analysis focused on the resolving the relationships of the higher taxa of the Saprininae subfamily, this new genus has been placed within a large and unresolved clade of genera that all share a unique synapomorphy of a single, pear-shaped vesicle inside the antennal club, as well as several weaker synapomorphies, which are possibly homoplasies (Lackner, unpublished). Within that large unresolved clade, Afroprinus was placed in a small dichotomy, sister to a South African member of the genus Pholioxenus, P. oleolus Thérond, 1965 that was included in the analysis to test the monophyly of the genus Pholioxenus. Both Afroprinus and P. oleolus are characterized by the putatively plesiomorphic feature of prosternal pre-apical foveae connected by marginal prosternal stria. Such a feature, which might also represent a convergence, is normally present among the members of the subgenera Hemisaprinus and Neosaprinus of the genus Euspilotus and its absence among other members of Pholioxenus points to the possible polyphyly of the genus. In the analysis, Hemisaprinus and Neosaprinus came out closer to the root of the cladogram unrelated to the large clade mentioned above. Cavernicolous habits are not common in the Histeridae, with most of the troglophilous genera belonging to subfamilies and tribes containing mostly microhisteridae: Dendrophilinae: Bacaniini (e.g. genera Troglobacanius Vomero, 1974, or Sardulus Patrizi, 1955, Abraeinae: Abraeini (genus Spelaeabraeus Moro, 1957), Acritini (genus Spelaeacritus Jeannel, 1934), see also Kovarik and Caterino (2005) for more thorough enumeration of the cavernicolous histerids. Speleacritus anophtalmus Jeannel, 1934 even shares some of the morphological adaptations that are typical of cavernicolous beetles: elongate body appendages, quasi-prognathous head, and fused elytra (Kovarik and Caterino 2005). In the Saprininae there are currently several genera whose species are known to have been collected inside caves: Gnathoncus Jacquelin du Val, 1858(G. cerberus Auzat, 1923and G. cavicola Normand, 1949, Tomogenius Marseul, 1862 (T. incisus (Erichson, 1842); T. ripiciola (Marseul, 1870); T. motocola Mazur, 1990 andT. papuaensis Gomy, 2007) (Kovarik & Caterino 2005 and Lackner, unpublished)). None of these taxa exhibit any morphological adaptations to the cavernicolous way of life and according to Kovarik & Caterino (2005), they are attracted to bat guano accumulated inside these caves and presumably feed on fly larvae developing in it. The habitat of Afroprinus, which is similar to the genera mentioned above, is atypical for the members of the large and poorly resolved clade of the yet unpublished phylogeny of the Saprininae subfamily. Typically, its other members, such as the genus Chalcionellus are predators inhabiting open areas and are normally found on dung or carcasses in dry or semiarid steppe zones, on shoals of rivers or beaches. This group contains all of the hitherto known true psammophiles, as well as an obligate termitoxene.
Regarding the Saprininae collected in caves in the Afrotropical region apart from Afroprinus cavicola, a single non-native species, Euspilotus (Neosaprinus) rubriculus (Marseul, 1855) has also been collected inside a cave. This Neotropical species (for details on its distribution see Mazur 2011: 192) has been introduced to the French island of La Réunion in the Indian Ocean and to the British Overseas Territory of Saint Helene in the Atlantic Ocean (Desbordes 1919;Thérond, 1972;Gomy 2005). Specimens collected on La Réunion have been found inside a lava tube in the faeces of the Mascarene Swiftlet (Collocalia francica Gmelin, 1789) (Gomy 2005). Gomy (2005) concluded that its cavernicolous habitat "n'a rien d'exceptionel" and hypothesized that this species could have come from Brazil with a shipment of some kind of legumes, probably soy beans or corn. The species seems to be well established on the island, since it has been collected in the same environment again (Gomy 2005). Perhaps the above-mentioned Saprininae taxa (including Afroprinus) that have been collected inside caves show an early stage of colonisation of the cave environment by Saprininae histerids. Saprininae are one of the most ecologically plastic histerids, occurring inside mammals' burrows, ant nests, on decomposing vegetation, on coastal wrack, deep under shifting sands, and even on flowering plants (see Lackner 2010 for details on Saprininae biology). The discovery of this peculiar new genus inside an African cave proves that our knowledge of Afrotropical Saprininae is still incomplete. this paper. Thanks are due to the curator of the institute mentioned above, Roger Booth, for his help with the specimens. I am likewise thankful to the two anonymous reviewers as well as the editor of Histeroidea of Zookeys for their comments and critical remarks, which undoubtedly produced a better work. This research was supported by the Internal Grant Agency (IGA n.20124364) Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Czech Republic.