Harpella melusinae is common and cosmopolitan in the Northern Hemisphere, as well as throughout New Zealand and in most parts of Australia where blackfly (Simuliidae) hosts occur. The species is found attached to the peritrophic membrane in the larval midgut. In our 1991 South Island collections we found H. melusinae in 10 stream sites, primarily in Austrosimulium australense (Schiner) and A. ungulatum Tonnoir, but also in other, unidentified larvae of Austrosimulium (the only simuliid genus known in New Zealand).

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: In addition to the type locality (site ZEA-94), we also found S. bullatum in unidentified Orthocladiinae larvae collected 15.11.91 from ledges at the base of Waipori Falls (site ZEA-85) located about 40 km SW of Dunedin.

Trichospores biconical, 20-24 x (5.5-) 6 (-7.2) µm, with a collar about 4 µm long. Young thalli consisting of an axis of wider cells from which narrower branches arise. Basal cell swollen, holdfast a small knoblike projection. Zygospores unknown. In hindgut of larval Orthocladiinae.

Trichosporae biconicae, 20-24 x (5.5-) 6 (-7.2) µm, collari circa 4 µm longo ornatae. Thalli juveniles ex axe e cellulis µmplioribus consistentes e quo rami angustiores producti. Cellula basalis inflata, tenaculum instar bullae parvae. Zygosporae ignotae.

ETYMOLOGY: Latin bullatum meaning with a knob. This new species differs from other described Smittium spp. in its thallus morphology, holdfast structure, and the shape and dimensions of its trichospores.

HOLOTYPE: Slide ZEA-94-1 prepared from the hindgut of a Naocladius forsythi Boothroyd larva (Chironomidae, Orthocladiinae) collected 22.11.91 from Wharf Creek at Hwy. 6 south of Haast Pass, South Island. Deposited with R. W. Lichtwardt, University of Kansas.

Like S. simulii, S. culicis is widespread and has been found living in several families of Nematocera. However, mosquito larvae (Culicidae) are the usual hosts. Williams and Lichtwardt (1990) reported finding S. culicis on North Island in a population of mosquito larvae (Culex pervigilans Bergroth) as well as in an unusual host, a solitary midge (Austrothaumalea sp. (Diptera, Thaumaleidae)). We present here the first report of S. culicis on South Island; it was found in the hindgut of one unidentified midge larva from Waipori Falls (site ZEA-85), along with another harpellid, Stachylina minima.

This species is not only very common worldwide but also has a wide host range among families of the dipteran suborder Nematocera. Its usual hosts are larval Chironomidae and Simuliidae. For the second time in New Zealand we found S. simulii in nymphs of the endemic stonefly genus Zelandoperla (Plecoptera, Gripopterygidae), the only nondipteran host known. Infested Zelandoperla nymphs were found in Cron Creek, west of Haast Pass, South Island (site ZEA-97).
Smittium simulii was also found in a population of A. australense larvae in Thompsons Creek (site ZEA-77, Hwy. 85 near Omakau) and in simuliids in Lust Creek (site ZEA-71, Hwy. 87 N of Middlemarch). Infested chironomid larvae included Cricotopus aucklandensis (Sublette & Worth) (Silverstream); Tanytarsus vespertinus Hutton (Manuherikia River, site ZEA-80 1 km SE of Hawkdun); Maoridiamesa sp. (Waterfall Creek (site ZEA-93, discharging into Lake Wanaka) and a small waterfall on Hwy. 6 W of Haast Pass); and three other unidentified species of Chironomidae.

Species of Stachylina, like Harpella spp., inhabit the midgut region of their dipteran hosts that are, with one known exception, species of Chironomidae. In 1987 we found St. minima in two chironomid populations on the Banks Peninsula and in one stream site west of Christchurch. A single midge larva with St. minima was found farther south in the current study (see S. culicis above). Stachylina minima appears to be an uncommon and probably endemic species in New Zealand. We did not find it on North Island.

Stachylina nana has a disjunct distribution. Originally described from a site in France, it has also been found in Japan (Lichtwardt et al. 1987) and from two sites on South Island (Williams and Lichtwardt 1990). We report here its occurrence in midge larvae of Tanytarsus vespertinus (site ZEA-80) (one of the host species in our 1987 collections) and in unidentified midge larvae from site ZEA-85.