Muhaka icipe, an enigmatic new genus and species of Kleidotomini (Hymenoptera: Figitidae: Eucoilinae) from an East African coastal forest

A remarkable new eucoiline genus and species, Muhaka icipe, is described herein. The genus is clearly a Kleidotomini, but is distinguished from other genera in the tribe by a unique head and scutellar morphology. The genus belongs to the ‘wedge-head’-syndrome group of species that, to date, is unique to Afrotropical eucoilines. The new genus and species is reminiscent of Stentorceps Quinlan and Nanocthulhu Buffington, but is readily distinguished from these genera. Muhaka was collected from a threatened kaya (sacred forest) of coastal Kenya. The biological importance of this and other kaya forests, as well as their protection, is discussed. http://www.zoobank.org/urn:lsid:zoobank.org:pub:6918ED2C-69A4-48FC-A1E4-2B5DFF58E876


Introduction
The coastal forests of Eastern Africa, stretching from southern Somalia to Mozambique, make up one of only eight biodiversity hotspots in Africa (CI 2013). Dotted along the East African coast are remnant indigenous forests of varying size of which, in Kenya, 200 ha.) on the north coast and Shimba Hills National Park (c.9600 ha.) on the south coast retain the greatest forest cover (Tabor et al. 2010). These remnants form an 'archipelago' of isolated forests in an ocean of farmland, and are thought to have once been part of a more-or-less continuous canopy forest that covered the East African coast. Together, the coastal forests provide refugia for many relict animal and plant species, and are characterized by their high degree of endemicity (Burgess et al. 1998), hence their importance for species conservation.
Muhaka Forest is one of many small forest-remnants, several of which, including Muhaka, are kaya, or sacred, forests. Originally thought to have afforded protection against invading Galla warriors, the kaya forests of the Mijikenda people of the Kenya coast also served religious and cultural purposes, and continue to do so (UNESCO 2013). For this reason they have been protected by village elders from encroachment by expanding local populations, resisting both clear-cut conversion to farmland and slower extirpation as trees are felled for firewood and building materials. Muhaka Forest is one of the larger kayas, covering about 150 ha. It is a wet deciduous forest (Waiyaki and Bennun 2000) with an average annual rainfall of 1151 mm (Foeken 1994). Rainfall is weakly bimodal and concentrated in the 'long rains' of April-June and the 'short rains' of October-December.
As part of a survey and inventory project of Kenyan insects, from 2004-2013, the second author sampled in several coastal forests, including Kaya Muhaka. To date, the project has discovered many interesting new species and provided insights into the geographical distribution of various insect groups, primarily Hymenoptera and Diptera. In fact, these Kenyan insect surveys have supplied several Hymenoptera projects with desperately needed material for understanding Afrotropical species diversity, abundance, and phenology van Noort 2009, 2012;van Noort and Buffington 2013;van Noort et al. 2015). The first author received some samples in 2013 that contained specimens of a genus and species hitherto unknown to science. This unusual wasp is named and described herein: Muhaka icipe Buffington & Copeland, new genus and species.

Specimen illustration and observation
The digital illustrations (Figures 1 and 3) were generated by Taina Litwak (scientific illustrator, Systematic Entomology Lab, USDA) from camera lucida pencil sketches of specimens, using scanning electron micrographs for reference to surface sculpture. Digital painting was done using the Adobe CS4™ package (San Jose, CA, USA). A Hitachi TM3000 desktop scanning electron microscope (Tokyo, Japan) was used to generate SEM images for Figure 2; specimens were photographed uncoated at 'analysis' voltage, running in 'compo' mode. Colour light microscope images were obtained using the EntoVision multiple-focus imaging system (Frederick, MD, USA) to illustrate diagnostic characters. Methods for generating these photographs follow those in Buffington and van Noort (2009). The resulting images (SEM and LM) were edited in Adobe CS4. All images are available from Morphbank. Direct specimen observation was made utilizing a Leica 205c stereomicroscope (Singapore) with fluorescent desk lamp light sources.

Descriptive format
Diagnoses focus on easily recognized gross morphologies, and closely related species are distinguished. Terminology for all descriptive characters follows Nielsen and Buffington (2011); surface sculpture terminology follows that of Harris (1979). The following new morphological terms are used.
• Kemnina ( Figure 2C): paired overhanging ridges present on the head immediately posterior to the toruli. Derived from Greek (kemnos) for 'overhanging wall or bank'.
• Ankos ( Figure 2C): particular pattern of ornamentation on the vertex, with a semicircular depression circumscribed by anterior and posterior ridge-like elevations. From the Greek (ankos) for 'mountain glen, valley'.

Diagnosis
Unique within Eucoilinae by the possession of a distinct valley-like depression on the vertex (ankos), encompassing the lateral ocelli, and whose anterior ridge directs the anterior ocellus in an anterior orientation; also unique within Eucoilinae is the possession of overhanging ridges over the toruli (kemnina). Superficially, Muhaka may be mistaken for Stentorceps or Nanocthulhu in that these three genera contain species with unusual head ornamentation, as well as relatively large, paddle-like mandibles. However, careful examination of the shape and position of these head characters readily separates Muhaka from the other two genera. Muhaka clearly belongs in the Kleidotomini, and its fore wing venation is characteristic of the tribe (Figures 1 and 3C). Within Kleidotomini, Muhaka is most similar in appearance to Triplasta species. Both taxa have weak striae on the lateral aspects of the pronotum and along the base of the syntergum of the metasoma. Additionally, in both genera the posterior margin of the metapleuron is distinct and the posterolateral 'face' on the ventral corner of the metapleuron is glabrous. However, in Triplasta species, the metasomal base is glabrous (setose in Muhaka).
Legs. Fore-and mid-coxae sub-equal in size, hind coxa twice as long as other coxae; all coxae glabrous; metacoxa without posterior dorsoventral hair line. Femora with sparse setal lines; tibiae and tarsomeres with dense, adpressed setae. Length of metatarsomere 1 slightly less than combined length of remaining metatarsomeres.

Etymology
Genus named in honour of Muhaka forest, the type-locality of the genus; it is a noun in apposition.

Diagnosis
As in diagnosis of the genus.

Description
As in description of genus with: Head. Nearly glabrous with a few scattered setae on inner orbits of compound eyes, frons, kemnina (torular sculpture) and ankos (central depression on vertex); ocellar hair patches absent ( Figure 2D). Genal carina absent, but blunt ridge present, glabrous. Longitudinal striae present along vertex, very weakly setose (Figure 2A). Lateral mandibular fold present along basal half of each mandible, containing a single, stout seta ( Figure 2B).
Pronotum. Lateral aspect of pronotum smooth, gentle striae present posterior to lateral margin of pronotal plate, as well as ventral to pronotal trough ( Figure 2C).
Mesoscutum. Glabrous and smooth except for pair of sparse setal lines along the length of the mesoscutum (in position of notauli) ( Figure 3A).
Mesopectus. Upper and lower part of mesopleuron completely smooth, with a few gentle striae anteriorly; glabrous ( Figure 2C).
Wings. R 1 incomplete along anterior margin of wing; marginal cell elongate; trace veins absent, M vein represented by setal line extending to apical margin of wing. Apical fringe medium length, longer along posterior margin.
Etymology icipe in honour of ICIPE, the International Centre of Insect Physiology and Ecology; it is a noun in apposition. ICIPE has been, and continues to be, a leader of entomological research in Africa.

Biology
Unknown. This species was collected in a 6 m Malaise trap set inside Muhaka Forest ( Figure 3D).

Discussion
Muhaka icipe joins a group of eucoiline genera from sub-Saharan Africa that exhibit highly specialized head ornamentation. The other eucoilines are the trichoplastines Stentorceps Quinlan (Quinlan 1984;Nielsen and Buffington 2011) and Nanocthulhu Buffington (Buffington 2012), and to a lesser extent, by the diglyphosematines Nordlanderia Quinlan and Ealata Quinlan (Buffington 2011), as with a few undescribed Afrotropical species of Rhoptromeris Förster and Hexacola Förster (van Noort et al. 2015). With the description of Muhaka, Kleidotomini is now added to this list. To date, the function of these head ornaments is unknown. Buffington (2012) noted a general lack of sexual dimorphism in species of these three tribes (except for typical antennal morphology and genitalic characters), and he hypothesized that these structures are used for escaping from subterranean host puparia. Hence, it is unlikely that Muhaka icipe, being only known from males, is simply the 'male version' of a previously described species; we hypothesize here that when females are eventually recorded, their morphology will be consistent with these herein described males. Divergence dating of the root nodes of these tribes reported in  suggests that representatives of the three tribes are separated by some 50-75 million years, suggesting that this head-morphology syndrome has resulted from convergence in the eucoiline body plan. This is perhaps most extraordinary in the convergence of mandible morphology, with the resulting paddle-like mandibles of Stentorceps, Nanocthulhlu and Muhaka (as well as those found in Tyrannoscelio Masner, Johnson and Arias-Penna, and other genera listed in Nielsen and Buffington 2011) directly linked to a specifically 'wedgehead' morphological syndrome. The presence of pyramidal protuberances or clypeal 'scoops' are quite common in Holarctic species of Diglyphosematini, namely Microstilba Foerster, Disorygma Foerster, Sinatra Buffington, and Ganaspidium Weld (Buffington 2011). In fact, there are some Afrotropical species of Rhoptromeris (Trichoplastini) and Ganaspis Förster (Ganaspini) that possess clypeal protuberances, and this morphological feature is not found in species from biogeographic regions outside of the Afrotropics (van Noort et al. 2015). These clypeal features, too, may be linked to emergence from the host puparium. A detailed study of micro-Hymenoptera cranial morphology is presently underway (coordinated by M. Buffington and M. Gates) but no data are yet available for improving our interpretation of these unusual features across the order.
Poaching of trees in Kenyan coastal forests is a constant threat due to increased population pressure and the breakdown of traditional values due to the growing popularity of aspects of western culture, and Kaya Muhaka is no exception. For small forest remnants such as that of Muhaka Forest, the immediate danger of ecosystem collapse is real. Recently, illegal tree felling has been detected in Muhaka Forest (RSC pers. obs., R. Pasquet pers. comm.). Hopefully the discovery of endemics such as Muhaka icipe will help build a case for more robust conservation strategies to safeguard these important habitats.