We originally described P. asymmetrica from larvae of A. tillyardianum Dumbleton collected at one site on South Island (Williams and Lichtwardt 1990). Conjugating branches, but no zygospores, were found in some of those larvae. We report here a 1991 collection of P. asymmetrica from A. australense larvae. The thalli of one of the simuliid larvae from site ZEA-100 (Silverstream, located west of Dunedin) were producing zygospores. Also, an immature thallus of what may have been P. asymmetrica was found in an Austrosimulium sp. larva collected in the Waipori River north of its confluence with Mill Creek (site ZEA-83).
The conjugation apparatus and biconical zygospores of P. asymmetrica resembled those of other Pennella spp. (which are type III (Moss et al. 1975)). The zygospores measured 60-70 x 12 µm and therefore have dimensions that differ from the other five described species of Pennella (see Lichtwardt 1986). Thus, P. asymmetrica is a distinct species on the basis of both trichospore and zygospore morphology.

COLLECTIONS: Known only from site 67, South Island. We observed one conjugation of branches between two thalli, but found no zygospores. Pennella asymmetrica was not found in any of the other 30 populations of simuliids (blackflies, often called sandflies in New Zealand) that we investigated for trichomycetes on both North and South Island. Nor did we find the genus Pennella in the many populations of simuliids that we studied in Australia.

Collarless trichospores ovoid, (35-)42(-52) x (12-)14(-17) µm, eccentrically attached at their base to a generative cell, each subterminal trichospore somewhat appressed to the generative cell above it, upon release bearing about four very fine appendages several times the length of the spore. Base of main thallial axis simple, with a mucilaginous secretion. Zygospores unknown. In hindgut of Simuliidae larvae.

HOSTS: Found only in Austrosimulium tillyardianum larvae (Diptera, Simuliidae). Most larval specimens were infested.

Trichosporae collaria carentes, ovoideae, (35-)42(-52) x (12-)14(-17) µm, oblique per basim ad cellulam genitalem affixae, omnibus subterminalibus paulum ad cellulam genitalem superiorem appressis, liberatae appendiculas pertenues circa quattuor aliquoties quam spora longiores. Axis thallici principalis basis simplex, mucum secretans. Zygosporae ignotae. In proctodaeo Simuliidarum larvarum.

Pennella asymmetrica has trichospores that are much wider than any of the other described species of the genus, and their eccentric attachment to the generative cell also assists in their identification.

HOLOTYPE: Slide ZEA-67-5 prepared from a larva of Austrosimulium tillyardianum Dumbleton (Simuliidae) collected from Manson's Creek, South Island, 9.II.87 (site 67). Deposited with R. W. Lichtwardt, University of Kansas. The slide also contains the larva's peritrophic membrane with Harpella melusinae.