Ecology, taxonomy and notes on the biology of members of the Colophon stokoei clade

Thesis (MScConsEcol)--Stellenbosch University, 2025.

Durie, J. I. 2025. Ecology, taxonomy and notes on the biology of members of the Colophon stokoei clade. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/22235af8-5ba3-4d1d-867e-185f38e17195

ENGLISH ABSTRACT: The Greater Cape Floristic Region boasts high plant and insect diversity with many endemic species. As the temperatures warmed since the last glacial period, many species have been driven to higher elevations in search of more favourable conditions. The high mountain peaks therefore now serve as refugia for many taxa, allowing for allopatric speciation. This includes the Cape Stag beetles (Genus Colophon). Colophon contains 22 flightless species restricted to the high-elevation peaks of the Western Cape province of South Africa. These beetles strongly associate with the Fynbos biome, specifically the montane fynbos, which is rich in restiod (Restionaceae) shrubs. The C. stokoei complex found in the Hottentots-Holland mountains was recently shown to comprise four species, each on a different or neighbouring peak. This study set out to survey peaks never previously surveyed, focusing on the Hottentots-Holland mountains, for the presence of Colophon, and to document the environmental factors that may affect its distribution, abundance, and future conservation. Six previously undocumented populations of Colophon were located. Based on morphology, one of these, collected from the Riviersonderend mountain range, was distinct from other species in the C. stokoei complex and was subsequently described as the new species Colophon scholtzi. Small but consistent differences in morphological and DNA sequence data from four of the six sampled populations, all from peaks in the Hottentots-Holland mountains, indicated that these warrant at least sub-specific status to other species in this complex until more information becomes available. Data from field monitoring indicated that these taxa were generally closely associated with the top of peaks ~1300 m asl. Beetles were most abundant in areas with a higher percentage of restios (living and dead) than other plant taxa. Larvae were often found in association with restio roots in humus-rich soils. Natural predation by scorpions, spiders, lizards, predatory birds, and small mammals was commonly encountered. The first evidence of adult subterranean behaviour is provided here. Males occupied the area close to the entrance of tunnel systems, apparently protecting it, while females occupy the same tunnels, but at lower locations. The biggest threats to Colophon recorded at these sites were land transformation for building cell phone towers and invasion by exotic Pinus spp. This study adds knowledge to the distribution, taxonomy, and ecology of Colophon. It serves as a strong basis for much-needed future research on the biology and ecology of these endangered beetles.

AFRIKAANSE OPSOMMING: Die Groter-Kaapse Floristiese Streek spog met 'n hoë plant- en insekdiversiteit met baie endemiese spesies. Soos die temperature sedert die laaste gletserperiode opgewarm het, is baie spesies na hoër hoogtes in bergreekse gedryf op soek na gunstiger toestande. Die hoë bergpieke dien dus nou as toevlugsoord vir baie taksa, wat voorsiening maak vir allopatriese spesiasie. Dit sluit die Kaapse grootkaakkewers (Genus Colophon) in. Kolophon bevat 22 vluglose spesies wat beperk is tot die hoë pieke van die Wes-Kaap provinsie van Suid- Afrika. Hierdie kewers assosieer sterk met die Fynbos-bioom, spesifiek die bergfynbos, wat ryk is aan restio (Restionaceae) struike. Daar is onlangs getoon dat die C. stokoei-kompleks wat in die Hottentots-Holland- berge gevind word, uit vier spesies bestaan, elk op 'n ander of naburige piek. Hierdie studie het ten doel gehad om pieke te ondersoek wat nog nooit voorheen ondersoek was vir die teenwoordigheid van Colophon nie, met die fokus op die Hottentots-Hollandberge, en om die omgewingsfaktore te dokumenteer wat die verspreiding, getalle en toekomstige bewaring daarvan kan beïnvloed. Ses voorheen ongedokumenteerde bevolkings van Colophon is opgespoor. Gebaseer op morfologie, was een hiervan, wat vanaf die Riviersonderend-bergreeks versamel is, verskullend van ander spesies in die C. stokoei-kompleks en is daarna beskryf as die nuwe spesie Colophon scholtzi. Klein maar konsekwente verskille in morfologiese en DNS- volgordedata van vier ander bevolkings, almal van pieke in die Hottentots-Hollandberge, het aangedui dat hul ten minste subspesifieke status regverdig totdat meer inligting beskikbaar word. Data van veldmonitering het aangedui dat hierdie taksa oor die algemeen nou geassosieer is met die top van pieke ~1300 m bo seespieël. Kewers was die volopste in gebiede met 'n hoër persentasie restios (lewend en dood) as ander planttaksa. Larwes is dikwels in assosiasie met restiowortels in humusryke gronde gevind. Natuurlike predasie deur skerpioene, spinnekoppe, akkedisse, roofvoëls en klein soogdiere is algemeen teëgekom. Die eerste bewyse van volwasse ondergrondse gedrag word hier verskaf. Mannetjies het die gebied naby die ingang van tonnelstelsels beset en dit blykbaar beskerm, terwyl wyfies dieselfde tonnels beset, maar op laer plekke. Die grootste bedreigings vir Colophon wat by hierdie terreine aangeteken is, was grondtransformasie vir die bou van selfoontorings en inval deur eksotiese Pinus spp. Hierdie studie voeg kennis by tot die verspreiding, taksonomie en ekologie van Colophon. Dit dien as 'n sterk basis vir broodnodige toekomstige navorsing oor die biologie en ekologie van hierdie bedreigde kewers.

Masters