https://europeanjournaloftaxonomy.eu/index.php/ejt/article/view/2151/9153
Revision of the enigmatic South African Cryptolaryngini (Coleoptera, Curculionidae), with description of a new genus and twenty-two new species.
Haran J.M., Marvaldi A.E., Benoit L., Oberlander K., Stals R. & Oberprieler R.G. 2023. European Journal of Taxonomy 877: 1–89. https://doi.org/10.5852/ejt.2023.877.2151
Abstract.
The weevil genus Cryptolarynx Van Schalkwyk, 1966 is endemic to the Northern and Western Cape provinces of South Africa. The two previously known species of the genus, C. vitis (Marshall, 1957) and C. estriatus (Marshall, 1957), have an aberrant globular body and head shape, which has made it difficult to place the genus into the classification systems of the Curculionoidea.
This paper presents the description of 21 new species of Cryptolarynx from South Africa ( ... C. oberprieleri ... C. oberlanderi ...) and of one new genus with species, Hadrocryptolarynx major. also from South Africa. A redescription of the genus Cryptolarynx is provided to incorporate the characters of the new species.
The plant genus Oxalis (Oxalidaceae) is recorded as larval host for several species of Cryptolarynx and for Hadrocryptolarynx as their larvae develop in the subterranean bulbs of members of the genus, and the egg, larva and pupa of C. variabilis are described.
The characters of the Cryptolarynx larva confirm that Cryptolaryngini are an early-diverging group of Curculionidae, with a placement among taxa currently classified in the subfamily Brachycerinae sensu lato,and although their exact taxonomic position remains unresolved, some larval characters, and also pupal ones, suggest a close relationship between Cryptolaryngini and Stenopelmus Schoenherr.
Potential use of species of Cryptolarynx in the biological control of weedy South African species of Oxalis is discussed.
Life History
Weevils are active in the austral winter (adults Jun-Oct, peaking July and August, rarely to Feb).
For C. variabilis in Stellenbosch; first adults emerge Jun-Jul and feed on aerial vegetation, resting on the soil by the stems, active in open areas during the hottest hours. Mating in July; gravid females end July; oviposition in September directly onto immature (non-sclerified) bulbs of Oxalis pes-caprae and O. purpurea, as these begin to wilt. Females dig vertically using mandibles. Larvae in Oxalis bulbs from Dec-Mar, but larvae only feed after bulbs sclerify. Larvae entirely consume the bulb, do not produce frass, size of adult depends on bulb size, over a fair range of sizes. Larvae go inactive in summer and pupate in March, pupae being of very short duration. Teneral remain in the bulbs, emerging via a circular basal or lateral hole in sclera in July. (Other species emerge at different times, suggesting chronologically specific life cycles).
Host plants
Closely associated with Oxalis. The weevils track their host plants by emerging early in the growing season in autumn, being active as adults during and after flowering, and then spending the heat and drought of summer as larvae inside the subterranean bulbs.
C. variabilis & C. oberprieleri: larvae on O. pes-caprae, O. purpurea and O. glabra.
(Other species by association only, but co-occurance prevents linking weevils to a specific Oxalis species).
Adults are polyphagous, feeding on leaves of several plant species (e.g. Grapes, Moraea, grasses, Arctotheca calendula), apparently avoiding leaves of their own larval host plants (unless, in labs, no other food is available) The larval damage to Oxalis bulbs is variable - C. variabilis: 5-25% of bulbs attacked.
No parasitoids are known. Adults are found in spider webs under stones, and larvae are eaten by rodents consuming Oxalis bulbs.
Behaviour
Adults diurnal, on the soil surface around larval hosts. Active during the warmer hours (occ. climbing onto vegetation in large numbers on hot afternoons). Can run very fast on hot sands. At sunset they hide in little holes under debris, stones or leaves that cover the ground. The head, eyes and mandibles seem to be for digging holes and tunnels in soil. Well camouflaged, feign death and retract head and appendages.
Seven months after a natural fire near Montagu, a large migration of adults of C. pyrophilus from unburnt vegetation to the burnt areas, where Oxalis was emerging, was noticed. Weevils appear to detect prolific Oxalis growth and flowering post fire from a distance away.
Six species of Cryptolarynx left in abeyance . Additional putative undescribed species morphologically different and genetic distanced. Not described as only female specimens , or as longer series are needed.
Read the paper for more.
Congratulations to Kenneth for his Weevil.
