Hadrorhyparus Howden, 1995

Hadrorhyparus Howden, 1995 View in CoL

Hadrorhyparus Howden, 1995: 23–25 View in CoL , figs 1–4. Type species: Hadrorhyparus pecki Howden, 1995: 25 View in CoL , by original designation.

Monteitheolus Howden & Storey, 2000: 180–182 View in CoL . Type species: Monteitheolus fijiensis Howden & Storey, 2000: 182 View in CoL , by original designation. New Synonymy.

Diagnosis. Hadrorhyparus shares many characters with Termitodiellus Nakane, 1961 : body not parallel sided, posteriorly convergent. Pronotum relatively large, broadest anteriorly, distinctly wider than long; lateral margin explanate, lobes notably dorsoventrally flattened. Elytra appearing short, notably narrowing caudally; widest near base humerus; posthumeral costa prominent at base, often reduced or absent by mid length; caudal trichome reduced or absent. Mesotibia flattened, variably triangular, gradually dilated toward apex; blade-like male mesotibial inner apical spur projecting along the axis of tibia, not perpendicular to tibia ( Termitodiellus - type: see Skelley 2007). The most notable derived characters that readily distinguish Hadrorhyparus from the morphologically diverse Termitodiellus are the greatly enlarged metathoracic legs, with modified and broadly triangular metatibia, and a reduction of the caudal bulb and trichome on the elytra.

Comments. The derivation of the name Hadrorhyparus was not stated by Howden (1995). “ Hadros ” is Greek for well developed or bulky. The type species is large and bulky in appearance, when compared to more typical Rhyparus or Termitodiellus . Because of their smaller size and more elongate body, this bulky condition is not obvious in other species now placed in the genus.

Termitodiellus has many diverse species, probably many are still undescribed, and is widespread from southeastern Asia and Indonesia into Oceania ( Krikken & Huijbregts 1987; Jiang & Wang 2020; Minkina & Kakizoe 2020; Anichtchenko & Vasiljeva 2021), but none are known east of New Guinea. It seems highly possible that the geographically isolated Hadrorhyparus and Monteitheolus are part of a broader Termitodiellus lineage with more modified metathoracic legs.

The most unusual character for Monteitheolus stated by Howden & Storey (2000) is a deep pit on each side of the central discal area of the head in which there “appears to be a number of eye facets”. These pits are present in all rhyparines but do not possess ocular facets. Studying the new photographs of the holotype ( Fig. 15 View FIGURES 10–16 ), the pits are obvious in the peridiscal groove, being similar to those of H. pecki , but no facets are visible. We feel this is simply a misinterpretation by the authors, and all other potential generic characters are shared with Hadrorhyparus .

Hadrorhyparus vitiensis , new species has a mix of characters previously distinguishing Hadrorhyparus from Monteitheolus , as well as possessing unique characters (e.g., elytral trichome present). Upon studying the type of M. fijiensis , we find its metathoracic leg development to be intermediate between Hadrorhyparus and Termitodiellus .

Instead of adding additional generic names to a highly derived tribe needing more detailed study at a generic level, our present conclusion is that Hadrorhyparus and Monteitheolus are similarly modified members of a broadly distributed and diverse Termitodiellus lineage. There are many undescribed new species of Termitodiellus known from scattered regions of Indonesia. Generic and species relationships within Termitodiellus need further study, after its known diversity is better described. For now, we consider these Fijian species, all with modified metatibiae and small to reduced caudal bulbs of the elytra, to be a single genus. Thus, we synonymize Monteitheolus under Hadrorhyparus and place our new species in Hadrorhyparus .