Malagasyprinus, a new genus of the Saprininae from Madagascar with description of two new species (Coleoptera, Histeridae, Saprininae) (First contribution to the knowledge of the Histeridae of Madagascar)

Abstract Based on the results of recent phylogenetic analysis of the higher taxa of the Saprininae as well as external morphological characters, especially the presence of deep and large prosternal foveae, and the shape and position of the sensory organs of the antennal club, the species Saprinus (s.str.) caeruleatus Lewis, 1905 is excluded from the genus Saprinus and a new genus Malagasyprinus, exclusive to Madagascar, is established for it. The new genus shows mainly characters that are apomorphic for the subfamily and contains another two, highly similar allopatric species Malagasyprinus perrieri sp. n., and Malagasyprinus diana sp. n., described herein. The three species are best separated from each other by the structure of the prosternum and male terminalia, especially the shape of the aedeagus. We re-describe Malagasyprinus caeruleatus comb. n. and provide Malagasyprinus perrieri and Malagasyprinus diana with brief differential diagnoses. All taxon descriptions are accompanied with color habitat photographs, SEM micrographs and drawings of their male genitalia. A key to the species of Malagasyprinus is given. Sensory structures of the antenna of Malagasyprinus caeruleatus comb. n. are likewise depicted herein. The systematic position of the newly erected genus is discussed. A lectotype of Saprinus caeruleatus Lewis, 1905 is designated.


Résumé
Se référant aux résultats des récentes analyses phylogénétiques portant sur les taxa supérieurs des Saprininae ainsi que sur des caractères morphologiques externes comme les larges et profondes fovéoles prosternales et les forme et position des organes sensoriels des massues antennaires, l'espèce Saprinus (s.str.) caeruleatus Lewis, 1905 Lewis (1905) described the species Saprinus caeruleatus based on a single specimen originating from southern Madagascar: Plateau de l'Androy, Région d'Ambovombe, adding a significant and explicative remark: 'I do not know of any species similar to this'. This assessment was perhaps why Dahlgren (1969: 263, fig. 2:A;267, fig. 3:I) depicted drawings of apices of the 8 th abdominal sternite of male as well as aedeagus based on the examination of four male specimens he found at MNHN collected by H. Perrier de la Bâthie in 1906. Probably because Dahlgren (1969) believed that he was dealing with such a well-characterized species he did not bother with the examination of its type specimen, housed at NHM. In this fashion, the identification process of specimens of 'Saprinus caeruleatus' has been simple and quick among the specialists on the Histeridae.
While mounting a larger series of this 'species' based on old as well as new collections, the junior author noticed significant differences between the aedeagi among the specimens. In the light of this discovery, the minor differences in external morphology, hitherto attributed to individual variation, suddenly gained significance. Furthermore, the senior author, when entrusted with a lot of recently collected specimens of 'Saprinus caeruleatus' discovered among them yet another, highly similar species. Based on these examinations, it became evident that 'Saprinus caeruleatus' is, in fact, a complex of three sibling species, which are described and compared below. Fortunately, the sole type specimen of S. caeruleatus, housed in NHM is a male and allowed us to fix its identity in the light of the discovery of the other new species, based on the male genitalia (especially aedeagus). The three species, although very similar externally, differ in the male terminalia as well as in external characters, and are also allopatric: while S. caeruleatus has so far been collected only in the southern part of the island, one of the newly described species occurs only in the west to north-west of Madagascar, while the other newly described species is found only in the northernmost tip of the great island (Fig. 62). As to Dahlgren's (Fig. 25) depictions of the eighth sternite and the apex of aedeagus, his drawings must be attributed to one of the newly described species, since the specimens he examined originated from Maevatanana (former Suberbieville), which is in the north-west of Madagascar.
During the PhD studies of the senior author a large number of species belonging to the Saprininae subfamily has been examined. Upon closer examination of S. caeruleatus, marked differences from the rest of the members of the genus were noticed and therefore a decision to include this species in the phylogenetic analysis of the subfamily was taken. Based on the results of the analysis (Lackner, unpublished), together with careful examination of the external morphological characters we decided to erect a new genus for the above-mentioned taxon that is characterized below.

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 antenna 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 1:1 mixture of glacial acetic acid and methyl salicylate heated at 60°C for 15 minutes and cleared in xylene. Specimens were then observed in α-terpineol in a small glass dish. Digital photographs of the male terminalia and antenna were taken by a Nikon 4500 Coolpix camera and edited in Adobe Photoshop CS4. Based on the photographs or direct observations, the genitalia and antennal structures were drawn using a light-box Hakuba klv-7000. SEM micrographs of Saprinus caeruleatus were taken with a JSM 6301F microscope at the laboratory of Faculty of Agriculture, Hokkaido University, Sapporo, Japan; while SEM micrographs of the newly-described species M. perrieri sp. n. and M. diana sp. n. were taken at the Laboratory of the Electron Microscopy at the Faculty of Biology, Charles University, Prague, Czech Republic. Habitat photographs of M. perrieri sp. n. were made by G. Goergen (Cotonou, Benin) and those of M. caeruleatus comb. n. and M. diana sp. n. were made by F. Slamka (Bratislava, Slovakia). All available specimens were measured with an ocular micrometer. Beetle terminology follows that of Ôhara (1994) and Lackner (2010). Separate lines of the same label are marked by slash (/). The following acronyms of museums and private collections are used throughout the text:  Lewis, 1905. Diagnosis. Rather small Saprininae histerid (PEL 2.05-2.60 mm) with black body, brown to black elytra; dorsally with blue metallic tinge; legs and antennae paler than the rest. Frons rugulose-lacunose, coarsely and densely punctured, depressed; frontal stria widely interrupted anteriorly, prolonged onto clypeus, sometimes difficult to discern and appearing complete; sensory structures of antenna in form of a single sensory area with a corresponding stipe-shaped vesicle situated on internal distal side of the antennal club (Fig. 22); eyes large and strongly convex; pronotal hypomeron asetose; pronotal foveae (sensu Lackner 2010: 38, fig. 146) absent, pronotum with variously deep longitudinal lateral depression separated from the pronotal margin by a slightly convex punctate band, median part of pronotum moderately to strongly convex, entire pronotal disc with coarse punctures, lateral longitudinal depression and surface around it with extremely rugose and deep longitudinal wrinkles; marginal pronotal stria carinate laterally, slightly bi-sinuate; entire elytral disc (with exception of small, occasionally punctate 'mirror' on fourth elytral interval) coarsely verrucose-punctate; dorsal elytral striae obliterated by punctuation, represented occasionally only by their basal fragments; basal fragment of fourth dorsal elytral stria and basal third to half of sutural elytral stria present as a rule, connected; humeral elytral stria usually discernible. Prosternal foveae (pre-apical foveae of Lackner 2010: 41, fig. 148) large and deep; both sets of prosternal striae present; prosternal process in two species depressed on anterior two-thirds; underside of the body with variously coarse and dense punctuation (depending on species). Differential diagnosis. Externally this new taxon at first glance resembles a specimen of the genus Saprinus s. str. (the type species of this genus has originally been a Saprinus), but the shape of the sensory structures of the antenna should distinguish it from Saprinus immediately (compare Figs 22 and 23). Furthermore, the deep longitudinal pronotal wrinkled depression with convex median part of the pronotum, and large and deep prosternal foveae quickly separate it from the members of Saprinus as well. However, prosternal foveae are present among the members of the primarily Palaearctic subgenus Hemisaprinus Kryzhanovskij in Kryzhanovskij and Reichardt 1976 of the genus Saprinus Erichson, 1834 but they are never as deep and large as in this newly erected genus, and, furthermore, the pronotal depressions (pronotal foveae of Lackner 2010: 38, fig. 146) are present in Hemisaprinus, whereas they are absent in Malagasyprinus. The most marked differences between Hemisaprinus and Malagasyprinus are found in the structure of their sensory areas of the antenna: the sensory structures of the antennal club of the type specimen of the subgenus Hemisaprinus, S. (Hemisaprinus) subvirescens (Ménétriés, 1832) are similar to those of S. semistriatus, and consist of four ovoid sensory areas on ventral side and one vesicle situated under internal distal margin (compare Figs 22 and 24). In order to distinguish this newly erected genus from other Afrotropical genera, the reader is referred to the key by the senior author (Lackner 2013: 66). Although this key features only the species "Saprinus caeruleatus", it is well applicable for all members of Malagasyprinus.

CAS
Biology. Series of M. caeruleatus comb. n. have been collected in a dry forest by a pitfall trap baited with fish. Specimens of M. perrieri sp. n. and M. diana sp. n. have been collected by beating the bushes, as well as by pitfall traps.
Distribution. Madagascar. Etymology. The name of this newly erected taxon is a combination of the genus name Saprinus with a prefix derived from the epithet suggesting Madagascar origin. Gender masculine.
Antennal scape (Fig. 6) slightly thickened, with shallow sparse punctures and three short setae; antennal club ( Fig. 5) round with slightly pointed tip, without visible articulation, entire surface with dense short sensillae intermingled with sparser longer erect sensillae; sensory structures of antennal club in form of a single oval sensory area situated on internal distal part of the antennal club with a corresponding stipe-shaped vesicle situated underneath (Fig. 22).
Mouthparts. Mandibles ( Fig. 6) with rounded outer margin, laterally with deep dense punctures, moderately curved inwardly, mandibular apex pointed; sub-apical tooth on inner margin of left mandible large, almost perpendicular; labrum ( Fig. 6 (Lewis, 1905) comb. n. 3 habitus dorsal view 4 ditto, ventral view 5 antennal club, ventral view 6 head, dorsal view 7 mentum, ventral view 8 prosternum 9 lateral disk of metaventrite and metepisternum 10 propygydium and pygidium 11 protibia, dorsal view. labial palpomere elongated, its width about half its length; mentum sub-trapezoid, anterior angles slightly produced; anterior margin ( Fig. 7) medially with slight emargination surrounded with six long setae, lateral margins with row of sparse shorter ramose setae, several setae present also on disc of mentum; cardo of maxilla with few short setae; stipes triangular, with three short setae; terminal maxillary palpomere elongated, its width about one-third its length, approximately three times as long as penultimate.
Pronotal sides moderately (Figs 1, 3) narrowing anteriorly, apical angles blunt, pronotal depressions absent; sides of pronotal disc with moderately deep longitudinal depression covered in deep longitudinal wrinkles, medially wrinkles disappear and become coarse and dense punctures; surface between longitudinal depression and pronotal margin slightly convex, punctate; marginal pronotal stria complete, laterally carinate and visible along its entire length from dorsal view; pronotal disc medially convex; pronotal hypomeron glabrous; scutellum small, but visible.
Elytral epipleura evenly punctate; marginal epipleural stria fine, complete; marginal elytral stria straight, well impressed and slightly carinate, continued as complete apical elytral stria. Humeral elytral stria weakly impressed on basal third, almost invisible under punctuation; inner subhumeral stria obliterated by coarse punctures; dorsal elytral striae (except for a tiny basal fragment of fourth dorsal elytral and complete sutural stria) completely erased by extremely coarse and dense elytral punctuation; fourth dorsal elytral stria present as short basal fragment connected with complete sutural elytral stria, which is apically connected with apical elytral stria; entire elytral disc (with exception of tiny punctate 'mirror' on fourth elytral interval) with extremely coarse and dense punctures, separated by less than half of their diameter; punctuation somewhat weakens before elytral apex.
Propygidium and pygidium (Fig. 10) densely and coarsely punctate, punctures separated by less than half of their diameter.
Intercoxal disc of the first abdominal sternite completely striate laterally; surface imbricate-punctate, punctures fine and sparse. Protibia (Fig. 11) slightly dilated, outer margin with seven moderately large triangular teeth topped by short rounded denticle, diminishing in size in proximal direction; setae of outer row very short and sparse; protarsal groove deep, substrigulate; anterior protibial stria shortened apically; setae of median row shorter than those of outer row; two tarsal denticles present near tarsal insertion; protibial spur short, bent, inserted on apical margin of protibia; apical margin of protibia posteriorly with one tiny denticle; outer part of posterior surface imbricate, separated from imbricate me-dian part of posterior surface by vague boundary and row of short sclerotized setae; posterior protibial stria complete, with a sparse row of tiny sclerotized setae becoming thicker apically; inner row of setae single, setae sparse and short.
Mesotibia slender, outer margin with two rows of sparsely spaced short denticles; setae of outer row regular, sparse, shorter than denticles; setae of median row regular, microscopic; posterior mesotibial stria complete; anterior surface of mesotibia imbricate; anterior mesotibial stria complete; mesotibial spur short; apical margin of mesotibia anteriorly with two short denticles; claws of apical tarsomere slightly bent, shorter than half its length; metatibia more slender and longer than mesotibia, in all aspects similar to it, but denticles on outer margin much sparser and claws of apical tarsomere slightly longer than half its length.
Differential diagnosis. From the highly similar M. perrieri sp. n., M. caeruleatus differs by smaller size; darker elytral cuticle (the elytra of M. perrieri are brown to dark brown whereas those of M. caeruleatus are pitch-black; compare Figs 1 and 26) shallower lateral longitudinal pronotal depression, and coarser elytral punctuation (in M. perrieri the elytral striae are more discernible whereas they are almost completely obliterated by punctuation in M. caeruleatus); furthermore, the elytral 'mirror' is often larger and less densely punctate in M. perrieri whereas it is tiny and often densely punctate in M. caeruleatus. The shape of carinal prosternal striae is likewise different between the two species: in M. caeruleatus they are strongly bi-sinuate, approximate medially and diverging, connected by a round loop, whereas in M. perrieri they are only slightly bi-sinuate, occasionally even sub-parallel (compare Figs 8 and 32) and furthermore, the prosternal process is medially deeply depressed in M. caeruleatus, whereas it is only slightly so with M. perrieri. However, the best marked differences are found among the aedeagi of the two species: in M. caeruleatus it is apically split in two inwardly curved halves resembling a snake's tongue and in M. perrieri it is simply pointed apically and not split (compare Distribution. Known exclusively from the south of Madagascar, regions of Antsimo-Andrefana, Androy and Anosy (Fig. 62).

Malagasyprinus perrieri
Diagnosis. Body measurements: PEL: 2.20-2.60 mm; APW: 0.90-1.00 mm; PPW: 1.75-2.15 mm; EL: 1.25-1.50 mm; EW: 2.00-2.50 mm. Very similar to the preceding species, differing mainly by larger size; lighter color of legs and antennae (those of M. perrieri are brown to dark brown whereas those of M. caeruleatus are rufescent; compare Figs 1-2 and 26-27) deeper longitudinal pronotal depression, sparser elytral punctuation (in M. perrieri the elytral striae are more discernible whereas they are almost completely obliterated by punctuation in M. caeruleatus); furthermore, the elytral 'mirror' is often larger and less densely punctate in M. perrieri whereas it is tiny and often densely punctate in M. caeruleatus (compare Figs 1 and 26). The shape the of carinal prosternal striae is likewise different between the two species, see comments to the preceding species and compare Figs 8 and 32. Aedeagi of the two species are markedly different: that one of M. caeruleatus is apically split in two inwardly curved halves resembling a snake's tongue and that one of M. perrieri is simply pointed apically and not split (compare Figs 18 and 40). Biology. This species has been collected by beating the thickets as well as by pitfall trapping in tropical dry forest.
Remarks. The specimens from Ankarafantsika (Ampisoro) slightly differ from those from national park of Baie de Baly in their punctuation of the ventral side of the body, but we regard these differences as variation between the two populations as the male genitalia are constant.

Malagasyprinus diana
Diagnosis. Body measurements: PEL: 2.20-2.30 mm; APW: 0.70-0.80 mm; PPW: 1.75-1.90 mm; EL: 1.40-1.50 mm; EW: 2.00-2.10 mm. Generally, this species has the deepest longitudinal pronotal depression and the largest area of the pronotum covered with deep longitudinal wrinkles. The elytral 'mirror' of M. diana is also the largest of the three species (compare Figs 1, 26 and 44 for the elytral sculpture of the three species). Furthermore, its carinal prosternal striae are rather widely separated, not approximate medially, only slightly diverging apically (compare Figs 8, 32 and 50 for the configuration of the prosternal striae among the three species) and the prosternal process is even, not depressed on anterior two-thirds. By the aedeagus (compare Figs 40 and 60) M. diana is most similar to M. perrieri, differing in the shape of 8 th sternite.
Distribution. Known only from the northernmost tip of the island, region of Diana, northern Madagascar (Fig. 62).

Discussion
In the recently performed phylogenetic analysis focused on the resolving the relationships of the higher taxa of the Saprininae subfamily, the species Saprinus (s.str.) caeruleatus has been included alongside the type species of the genus, S. semistriatus as there was a significant doubt that these two are actually congeneric. The reason for such doubt was mainly the conspicuously different structure of the sensory organs of the antennal club and the presence of large and deep prosternal foveae. The results of the yet unpublished analysis completely confirmed the initial suspicion as S. caeruleatus has been placed distant from S. semistriatus (Fig. 63), sister to a large and unresolved clade of genera that all share a unique synapomorphy of a single, stipe-shaped vesicle inside the antennal club, as well as several weaker synapomorphies, which are possibly homoplasies (Lackner, unpublished). The presence of the deep and large prosternal foveae exhibited by S. caeruleatus is also completely unnatural among the members of Saprinus, with only the Palaearctic subgenus Hemisaprinus possessing them. As this character is mainly present among the more 'derived' members of the Saprininae subfamily, it is apomorphic. Another apomorphic character is the single sensory area with the corresponding stipe-shaped vesicle situated underneath on the internal-distal side of the antennal club, as the taxa that are placed near the root of the tree possess in most cases two or more vesicles inside their antennal club. When Lewis (1905) famously remarked 'I do not know of any species similar to this' little did he know that his quip will provide a reason for a thorough study of the Malagasy specimens of 'Saprinus caeruleatus' which would yield another two, albeit very similar un-described species, and that his 'S. caeruleatus' will rightly be awarded generic rank. It is highly likely that the three species of this newly erected genus share a single ancestor that reached Madagascar and subsequently speciated there. Based on the scant data available, we can hypothesize that the species M. perrieri and M. diana are closest relatives since their aedeagi are very similar, with M. caeruleatus as their common relative. However, the immediate ancestor of the three Malagasyprinus taxa is unknown, as we are unaware of a similar taxon either from Afrotropical region or from the Indian subcontinent. Pepina Artimová is thanked for help with Adobe Illustrator CS5. Thanks are due to Petr Baňař (Brno, Czech Republic) for the map of Madagascar used in this paper as well as for many valuable comments and suggestions. We thank photographers G. Goergen (Cotonou, Benin) and F. Slamka (Bratislava, Slovakia) for their help with the habitus photographs of M. perrieri and M. caeruleatus and M. diana, respectively. Authors thank one anonymous reviewer and the editor of Histeroidea for Zookeys for their input with reviewing this manuscript. The curators of the institutes mentioned above are duly acknowledged for their help with the specimens. 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.