Revision of the genera Hovadelium Ardoin and Mimolaena Ardoin (Coleoptera, Tenebrionidae, Laenini) from Madagascar, with remarks on tribal assignment1

Abstract The genera Hovadelium Ardoin, 1961 and Mimolaena Ardoin, 1961, endemic in Madagascar, are revised and assigned to the tribe Laenini Seidlitz, 1896 (subfamily Lagriinae Latreille, 1825). New species: Hovadelium ardoini sp. n., Hovadelium bremeri sp. n. and Mimolaena janaki sp. n. An identification key is compiled for all taxa. Distribution of Hovadelium (5 species) and Mimolaena (3 species) is mapped. The congeners might be indicator species for the highly endangered mature forests in Madagascar.

In the revision of the tribe Adeliini, Matthews (1998) mentioned, that the tribal assignment of the Malagasy genera Hovadelium and Mimolaena either to Adeliini or to Laenini remains doubtful. Both genera are placed now herein finally into Laenini because of the lack of defensive glands. Different genera of this tribe are also known from South Africa (Endrödy-Younga andSchawaller 2002, Ferrer 2005).
So far, all descriptions were based only on single specimens. Recently, a huge number of newly collected specimens, mainly of Hovadelium, were handed over to the author for examination by Prof. Dr. H. J. Bremer (Osnabrück, Germany). This material, including three so far undescribed species, is represented herein, together with reexamination of the previously described taxa.
As other members of Laenini, all species are wingless and have restricted distributional patterns (Map see Fig. 1). So far, all records originate from the southeastern part of the island, additional taxa might be present in the northeastern part. Living in litter of the broadleaved evergreen forests, the congeners can be considered as indicator species for these mature and highly endangered forests in Madagascar.

Tribal assignment
Some specimens of Hovadelium ardoini sp. n. were sent to E. Matthews (Adelaide) for a personal dissection of the female genital tract. The examination showed, that defensive glands are completely absent in all the dissected specimens, which is characteristic for Laenini and the only difference to Adeliini. Matthews (in litteris): "I have dissected the females and can't see any trace of defensive glands, certainly not the long ones between segments 8 and 9 which are found in all Adeliini. There are no 7/8 glands either, although finding those in Laenini would not be surprising since they are characteristic of many Lagriinae. Stridulatory files (plectron) are absent. There are also no vaginal sclerites, such as the ones I found in one Laena (and most Adeliini). The spermatheca consists of three short wide tubules on the side of the vagina, similar to those of a species of Laena (Matthews 1998: fig. 57) which however has two long narrow tubules. Too few Laenini have been dissected for us to know the significance of these details, but the general configuration of the female system is typical of Laenini/Adeliini. The aedeagus of the male is of the usual simple type." Ovipositor and female genital tract ( Fig. 15): Paraproct and coxite subequal in length, coxite lobes 3 and 4 fused, digitiform, gonostyles terminal in position, coxite baculi transverse, paraproct baculi longitudinal, spiculum gastrale a slender rod without terminal fork. No bursa copulatrix, three short and wide spermathecal tubules attached to side of vagina, vaginal sclerites absent, long slender spermathecal accessory gland attached to anterior end of vagina. Diagnostic characters. Body length 2.7-4.0 mm (the holotype has a length of 4.0 mm and not of 5.0 mm as given by Ardoin 1961). Pronotum subquadrate, widest before the middle, with rounded anterior and posterior angles, surface slightly convex, with fine and sparse punctation, between punctation slightly shagreened. Elytra with punctural rows in striae, intervals convex, slightly shagreened and with an irregular row of tubercles, interval 7 at base near shoulders with a longer seta. Aedeagus see Fig. 10. Diagnosis. H. ardoini sp. n. is similar to H. discoidale Ardoin, 1961, but lacks the striking deep groove ventral of the eyes. Both can be separated also by the shape of the pronotum widest behind the middle in H. discoidale (Fig. 5), but widest in the middle in H. ardoini sp. n. (Fig. 3), and by the anterior angles of the pronotum, which are distinctly marked in H. discoidale, and completely rounded in H. ardoini sp. n. The elytral punctural rows are identical in both species, but the disc of the elytra is flattened in H. discoidale, whereas in H. ardoini sp. n. the elytra are more convex. See also under Hovadelium bremeri sp. n. and key below.
Description. Body length 3.3-4.7 mm, unicoloured dark brown. Eyes flat, not prominent; without a deep groove ventral of the eyes. Head with deep clypeal suture and two pairs of long setae as characteristic for the genus; frons shining and without punctures. Shape of the antennomeres see Fig. 3. Pronotum subquadrate, widest in the middle, anterior and posterior angles completely rounded, anterior and posterior margin finely bordered, lateral margins with broader border, anterior margin not excavated; surface slightly convex, with fine and sparse punctation, punctures only weakly impressed, surface between punctation shining and only slightly shagreened; propleura shining, without punctation. Elytra with nine punctural rows in distinct striae, these punctures small and elongate, only slightly broader than striae, without setae; intervals convex, shining and without punctures nor tubercles, interval 7 at base near shoulders with a longer seta. Ventrites shining, ventrites 1-4 in the middle with a pair of longer setae, last ventrite in both sexes unbordered. Femora and tibiae in both sexes without teeth or other modifications. In males protarsi only slightly dilatated, without other external differences. Aedeagus see Fig. 11.
Etymology. Named in honour of Jean Paul Ardoin (1918Ardoin ( -1978, former pharmacist in Arcachon (France), author of the Malagasy genera of Laenini and specialist of other tenebrionids from Africa and Madagascar. Diagnosis. Hovadelium bremeri sp. n. and Hovadelium ardoini sp. n. are similar, both share the general body shape, the lacking of a groove ventral of the eyes, the shining surface of pronotum and elytra, the elytral interval 7 at base near shoulders with a longer seta, and the lacking tubercles on the elytral intervals. In H. bremeri sp. n., the body length is somewhat shorter in the average, the pronotum is narrower towards base, the pronotal punctation is larger and denser, the anterior pronotal margin is unbordered in the middle, the punctures of the elytral rows are larger, and the apicale of the aedeagus is shorter. See also under Hovadelium ardoini sp. n. and key below.
Description. Body length 2.8-3.5 mm, unicoloured dark brown. Eyes flat, not prominent; without a deep groove ventral of the eyes. Head with deep clypeal suture and two pairs of long setae as characteristic for the genus; frons shining and without punctures. Shape of the antennomeres see Fig. 4. Pronotum subquadrate, widest in the middle, anterior and posterior angles completely rounded, anterior margin unbordered in the middle, posterior margin finely bordered, lateral margins with broader border, anterior margin not excavated; surface slightly convex, with irregular larger, but not confluent punctation, punctures only weakly impressed, surface between punctation shining; propleura shining, without punctation. Elytra with nine punctural rows in weak striae, these punctures large and broader than striae, without setae; intervals convex, shining and without punctures nor tubercles, interval 7 at base near shoulders with a longer seta. Ventrites shining, ventrites 1-4 in the middle with a pair of longer setae, last ventrite in both sexes unbordered. Femora and tibiae in both sexes without teeth or other modifications. In males protarsi only slightly dilatated, without other external differences. Aedeagus see Fig. 12.
Etymology. Named in honour of Prof. Dr. H. J. Bremer (Osnabrück, Germany), who provided me with most of the newly collected specimens, and allowed to keep the larger part in SMNS.
Remarks. The type specimen has a quite unique character, namely the head with a deep groove ventral of the eyes (Fig. 5). Ardoin (1961) assumed that this might be a sexualdimorph character of males within the genus. However, in all the plenty herein presented males and females of other species of Hovadelium, such a groove is not present. Thus, this structure (of unknown biological function) is considered as not generic but just as specific for H. discoidale. Unfortunately, an exact type locality is unknown.
Diagnostic characters. Body length 4.2 mm (not 5.0 mm as given by Ardoin 1961). Head with a deep groove ventral of the eyes (Fig. 5). Pronotum subquadrate, widest somewhat behind the middle, with marked anterior and rounded posterior angles, surface slightly convex, with fine and sparse punctation, between punctation slightly shagreened. Elytra with punctural rows in striae, intervals convex, shining and without tubercles, interval 7 at base near shoulders with a longer seta. Aedeagus not examined herein (because of the fragility of the type). Remarks. I hope not to fail in assigning the newly collected specimens to this species, described upon a single female. Distinct differences between the description and the new specimens do not exist, and the larger part of the new material originates from the surroundings of the type locality nearby Fort Dauphin.
Diagnostic characters. Body length 4.4 mm. Pronotum subquadrate, with slightly prominent anterior and with rounded posterior angles, surface slightly convex and with rough and partly confluent punctures. Elytra with rough irregular punctation without any separation in rows and intervals. Aedeagus unknown, only ♀ holotype known.  Diagnosis. To be recognized by the shape of the pronotum with spine-like posterior angles, by scattered and fine punctation of the pronotum, by only six elytral rows of punctures extinguished in the posterior and external part of elytra, and by the shape of the aedeagus. The two other known species of Mimolaena possess nearly rounded posterior angles of the pronotum, and the punctation on the pronotum is either fine and the elytra bear punctural rows (M. pauliani Ardoin, 1961), or the punctation on the pronotum is rough and dense and the elytra bear an dense irregular punctation not separated in rows and intervals (M. clarissae Ferrer, 1998). See also key below.

Mimolaena janaki
Description. Body length 3.5-4.7 mm, unicoloured dark brown. Eyes (Fig. 8) not reduced, slightly prominent. Shape of the antennomeres see Fig. 8. Shape of pronotum see Fig. 8, disc with a few scattered punctures, most punctures bearing a longer erect seta; surface without any impressions, surface shining, lateral margins bordered, basal margin bordered and not bent downwards, posterior angles prominent spinelike, propleura unpunctured. Elytra (Fig. 8) with only six punctural rows without striae, these rows extinguishing in posterior and external part of elytra, punctures of rows of similar size as pronotal punctures, punctures of the elytral rows without setae, a few additional punctures apart from the rows laterally and distally on the elytra bear a longer erect seta, intervals shining without any punctures and setation, intervals flat. Ventrites shining, in males with fine punctation and short setation, in females nearly unpunctured and without setation, last ventrite in both sexes unbordered. Femora and tibiae in both sexes without teeth or other modifications. Aedeagus see Fig. 14.

Mimolaena pauliani
Diagnostic characters. Body length 4.4-4.8 mm. Pronotum subquadrate, with rounded anterior and posterior angles, surface flat and with sparse and fine punctation. Elytra with distinct punctural rows without striae, size of the punctures diminishing laterally and apically. Aedeagus not examined herein (because of the fragility of the type). It is said (but not figured) in the description, that the apicale is short and acute at the tip, and the basale is long and bent. Lateral margin of pronotum regularly rounded towards anterior and posterior angles, anterior margin of pronotum completely bordered, pronotal punctation fine, punctures of elytral rows small, elongate and not distinctly broader than distinct striae - Fig. 3  Dr. Eric Matthews (Adelaide) dissected some female genitalia, provided a figure, recognised the assignment to the tribe Laenini and generously allowed me to publish the results herein. The photographs were taken by Johannes Reibnitz (Stuttgart) with a Leica DFC320 digital camera on a Leica MZ16 APO microscope and subsequently processed by him with Auto-Montage (Syncroscopy) software. Two referees, unknown to me, improved the manuscript by their comments and corrections.