Megalara
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Ordo: Hymenoptera
Familia: Crabronidae
Name
Megalara Kimsey & Ohl gen. n. – Wikispecies link – ZooBank link – Pensoft Profile
Type species
Megalara garuda Kimsey and Ohl, new species.
Generic diagnosis
Megalara is closely related to Liris Fabricius, Larra Fabricius, Dalara, Paraliris, and Dicranorhina Shuckard, which together are classified as Larrina (Pulawski 2011[1]) based on the presence of a horizontal swelling below the midocellus combined with a vertical swelling along the inner eye margin. The new genus is similar to Dalara and Paraliris in having the mandibles bidentate apically or very long, at most with a weak notch on outer margin. Within this group of genera, Megalara can be distinguished by the large body size (25-34 mm; 20-24 mm in Paraliris). A unique character of Megalara is the markedly developed malar space, whereas all other genera in the Larrina have the malar space narrow or virtually absent. Additionally, the propodeal dorsum is punctate in Megalara, but finely, transversely striatorugose in Dalara and Paraliris. A subsidiary recognition character is the dark body pubescence, which is markedly developed in females, but indistinct in males (body covered with dense, silvery pubescence in Paraliris, erect pubescence lacking at all in Dalara).
Males of Megalara have a number of complementary diagnostic characters: One of the most remarkable characters is the enormously enlarged male mandibles, which are almost as long as the forelegs. All species of Dalara and some of Paraliris also have elongate mandibles in the males, but shape and dentition are different. In Megalara, the mandibular apex is simple and the inner, subbasal tooth is greatly enlarged. In Dalara, the male mandible has one small subapical and one large subbasal tooth, whereas in Paraliris, the mandible is broadly bidentate apically in minor males and lacks subapical and subbasal teeth in major males with elongate mandibles. Other male characters diagnostic for Megalara are the hindfemoral venter, which is longitudinally compressed (evenly, slightly convex in Paraliris, with a hook-like process or prominent bulge toward base in Dalara), metasomal sterna III-IV with paired submedial lobes (simple in Paraliris and Dalara), sternum VIII bilobed apically (truncate in Paraliris, roundly truncate with a small median notch in Dalara), and the penis valve with a longitudinal row of markedly strong teeth on the ventral side (in Paraliris, penis valve with inwards directed apical and medial process, without ventral teeth).
Females of Megalara and Paraliris are generally quite similar and can be distinguished by the larger body size of Megalara, the dark pubescence in Megalara (silvery in Paraliris), and the propodeal dorsum, which is punctate in Megalara and finely, transversely striatorugose in Paraliris. Female Megalara and Dalara can be readily differentiated by dull or weakly, shining virtually asetose metasomal terga and the significantly different body sizes.
Partial modification of the key to Old World genera of Larrini by Bohart and Menke (1976)[2], replacing couplet 6
Discussion
Dalara, Paraliris, and Megalara, the newly described genus, share many morphological details with Liris. Menke in Bohart and Menke (1976)[2] said that Dalara ‘possibly should be considered as a subgenus of Liris … although the biology argues otherwise’. Liris is a morphologically diverse genus and has been split up into several genera or subgenera by various authors in the past (see Bohart and Menke 1976[2], for a taxonomic summary). It includes more than 310 currently valid species and its monophyly has never been formally tested. The newly described species, Megalara garuda, shares a number of significant characters with Paraliris, and we have considered placing Megalara garuda as an aberrant species in this genus. However, despite the similarities, the morphological differences are so striking, that we feel that the systematic position quite apart from all other species in Paraliris is best reflected by placing it in a genus of its own. Thus despite the lack of a comprehensive phylogenetic analysis of the genera in the Larrini, Dalara, Paraliris, and Megalara each exhibit a unique set of putatively apomorphic characters, so that the taxonomic status of all of them as distinct genera seems to be fully justified. However, a formal phylogenetic analysis of the Larrini on the genus level is desperately needed to test this assumption.
The enormously enlarged male mandibles of Megalara are quite similar to that of male Dalara, but Megalara is more similar to Paraliris in most details. Paraliris has been revised by van der Vecht (1982)[3], and one of us (MO) reexamined most of the specimens of the genus, which van der Vecht studied. Van der Vecht pointed out that males of at least Paraliris kriechbaumeri, show a remarkable amount of allometric variation with respect to general body size and mandibular length. Male body length varies from 15 to 22 mm, and the mandibles of the smallest males are very similar to female mandibles in being stout and broadly bidentate apically, whereas the mandibles of the largest males are elongate, sickle-shaped and simply apically and basally (van der Vecht 1982[3]: Figs 2–4). Despite these enormous differences particularly in mandibular size and shape, van der Vecht felt confident, based on a study by de Beaumont (1943)[4], that this represents an unusually broad range of intraspecific variation.
This hypothesis seems to be well founded, and we observe the same phenomenon in the newly described Megalara. There are two male morphs with remarkable differences in body size and mandibular size. Minor males, which have relatively short, female-like mandibles, are 25 mm long, whereas major males with exaggerated mandibles have a body length of 32 to 34 mm. However, the genital foramen and genital capsule of the minor male was packed with mites and it may also be that this individual was feminized by the heavy mite load. Unfortunately, the genital capsule was lost.
Van der Vecht (1982)[3] also pointed out that Paraliris bears ‘acarinaria’, which are specialized, typically pouch-like structures in aculeate Hymenoptera, which function to carry phoretic mites. In Paraliris, acarinaria are located beneath a lamella near the base of terga II–V (females) and II–VI (males). These areas are dorsally covered by the overhanging posterior margin of the tergum before the acarinaria-carrying tergum. Therefore, if present, phoretic mites in acarinaria can be seen in the intersegmental gap beneath the tergal overhang even in complete specimens. In Megalara, we observed mites in both sexes as follows:
Males. 1 major male: 2 mites between terga II and III
Minor male: genitalia packed with mites
Females. 1 female: 10 mites between terga II and III
1 female: 16 mites between terga II and III, 6 between III and IV
The presence of two mites on the terga and the large number in the genitalia in males are probably no indication of acarinaria in Megalara. However, the large number of mites in the females indicates that Megalara also possesses mite-bearing structures. Due to the small number of specimens of the new species, we refrained from dissecting the type specimens to verify the presence of acarinaria. Presence of acarinaria in Paraliris and putatively in Megalara also is another indication of the close relationships between these genera.
Etymology
The new genus name is an arbitrary combination of Mega-, deriving from the Greek megas, meaning large and mighty, and –lara, the last syllable of Dalara. It is an allusion both to the exaggerated body size of the new genus and its overall similarity to Dalara.
Original Description
- Kimsey, L; Ohl, M; 2012: Megalara garuda, a new genus and species of larrine wasps from Indonesia (Larrinae, Crabronidae, Hymenoptera) ZooKeys, 177: 49-57. doi
Other References
- ↑ Pulawski W (2011) Family group names and classification. http://research.calacademy.org/ent/catalog_sphecidae [last accessed 7 Nov 2011].
- ↑ 2.0 2.1 2.2 2.3 Bohart R, Menke A (1976) Sphecid wasps of the world. A generic revision. University of California Press, Berkeley, Los Angeles, London, ix + 695 pp.
- ↑ 3.0 3.1 3.2 Van der Vecht J (1982) Paraliris, an Oriental genus of mite-bearing larrine wasps (Hym., Sphecidae, Larrinae). Mitteilungen der Schweizerischen Entomologischen Gesellschaft 54 (1981): 357-361.
- ↑ De Beaumont J (1943) Systématique et croissance disharmonique. Mitteilungen der Schweizerischen Entomologischen Gesellschaft 19: 45-52.
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