Abstract
Investigations of type material and new material from the Philippines (Luzon) revealed that Baetis luzonensis Müller-Liebenau, 1982 and B. realonae Müller-Liebenau, 1982 do not belong to Baetis Leach, 1815. A new genus, Philibaetisgen. nov., is described to accommodate both species and both are re-described based on larvae. The new genus is characterised by having a rectangular labrum with a submarginal row of long, simple setae on the dorsal surface and ventrally on lateral margins long, simple, spine-like setae, on anterolateral margins long, feathered setae and medially long, bifid setae and a partial, submarginal row of lanceolate setae. Both mandibles have blade-like incisors and dorsally, a mediolateral patch of long, spine-like setae; additionally, the left mandible has a tuft of long, partly branched setae at the base of the subtriangular process. Philibaetisgen. nov. is further characterised by a hypopharynx with a medial tuft of stout setae and anterolaterally, two smaller tufts of stout setae, a galea-lacinia with the distal denti-seta tooth-like and directed against canines, a fore femur apically with stout setae, both on anterior and posterior side and without a femoral patch and a claw with one row of denticles and two or three subapical setae. The protogonostyli under the cuticle of male last instar larvae are folded in the Labiobaetis type, excluding their affiliation to the genus Baetis. COI sequences were obtained from both species. The genetic distance (Kimura 2-parameter) between them is 17.5% on average. Very limited genetic distances of 0% to 3% (0.75% on average) were found between specimens of P. luzonensiscomb. nov.
Highlights
The family Baetidae has the highest species diversity amongst mayflies, comprising ca. 1,100 species in 114 genera (Sartori and Brittain 2015, Jacobus et al 2019, Cruz et al 2020, Kluge 2020), which is close to one third of all mayfly species worldwide
Philibaetis gen. nov. obviously belongs to the family Baetidae, based on the developing turbinate eyes of late instar male larvae, the long, slender body shape, the larval Y-shaped frontal suture reaching ventrally to lateral ocelli (Fig. 8c), the labrum with distinctly-expressed median incision, the shape of left and right prostheca, the kinetodontium fused with mandible and with incisor, the shape of glossae and the anterior outer projection of femur apex, which is directed towards inner side of femur (Figs 3a, 7a) (Wang and McCafferty 1996, Kluge 2004, Kluge and Novikova 2011)
Philibaetis gen. nov. is preliminarily placed within the tribe Labiobaetini Kluge and Novikova (2016) since the final placement can be only definitely done once the male imago is described as well
Summary
The family Baetidae has the highest species diversity amongst mayflies, comprising ca. 1,100 species in 114 genera (Sartori and Brittain 2015, Jacobus et al 2019, Cruz et al 2020, Kluge 2020), which is close to one third of all mayfly species worldwide.
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