Poitrasia circinanscan be isolated from soil in Florida during the summer and probably other regions whereBlakeslea trisporaandChoanephora cucurbitarumalso are encountered.Poitrasiais not commonly reported but may be overlooked because the sporangia only are formed on a few, nutrient-poor media not commonly used in soil studies. On most media Poitrasia looks likeChoanephora cucurbitarumorBlakeslea trisporacolonies that do not form sporulating structures. (Zygomycetes.org 2015)
Colonies grown on agar start off white then turn to light beige. Aerial mycelium are aseptate and often highly branched. Colonies have irregular margins and smell like yeast. (Hesseltine & Benjamin, 1957; Kirk, 1984)
Sporangiophores are light brown, erect to ascending, aseptate, unbranching, up to 0.5-2 mm tall, 5-15 µm wide, with a smooth, hyaline base and purple to purple-brown upper portion below the sporangium. Sometimes the apex of the sporangiophore is recurved and somewhat swollen. (Hesseltine & Benjamin, 1957; Kirk, 1984)
Sporangia are infrequent and with few spores. They are (15)40-80(120) µm in diameter, starting off white and turning brownish-black at maturity. The persistent sporangial wall is covered with capitate spines less than 1 µm long. Columellae (when present) are obovoid to pyriform, hyaline to light brown, 25-67 µm wide, and 30-104 µm long. Sporangiospores are irregularly ellipsoid, pale brown, (5)7-12(14) µm long, (3)5-7(9) µm wide, with appendages up to 16.5 µm long emerging from the poles. Spores 8-18 µm wide. (Hesseltine & Benjamin, 1957; Kirk, 1984)
Chlamydospores are ellipsoid to subglobose, 10-22 µm long, 6-16 µm wide, with thick walls, hyaline to pale yellow. Zygospores are 60-100 µm wide, spherical to somewhat flattened spheres, generally with a large central oil droplet at maturity, thin outer wall, thick striated inner wall. Suspensors are tong-shaped, 10-20 µm wide. Poitrasia circinans is heterothallic. (Hesseltine & Benjamin, 1957; Kirk, 1984)
This species differs from its close relatives in the Choanephoraceae family in that it does not form dehiscent or indehiscent sporangiola. (Hyde et al., 2014)
This species is generally observed as a saprobe in soils, but there has been at least one instance where it has been observed as a pathogen in horsetails (Equisetum arvense). (Rai, 1990) It can be found in Florida soils during the summer months (Kirk, 1984), but its distribution is cosmopolitan.
This species has no significant role as a pathogen in an agricultural setting, and it does not appear to have an observable effect on ecosystems. However the difficulty in identifying this organism to a species level due to its infrequent sporangia production may lead to an underestimation of its function in ecosystems.
The species Poitrasia circinans belongs to the family Choanephoraceae, order Mucorales. It has two synonyms. It was first described as Blakeslea circinans by H. Naganishi and H. Kawakami in 1955. (Naganishi & Kawakami, 1955) The same species was described as Choanephora circinans by C.W. Hesseltine and C.R. Benjamin in 1957 when they wrote about Choanephoraceae. (Hesseltine & Benjamin, 1957) The current name Poitrasia circinans was given by P.M. Kirk in 1984 based on molecular evidence. Kirk also moved both of the formerly recognized varieties (C. circinans var. indica and C. circinans var. prolifera) into the current single species. (Kirk, 1984) It is the only member of its genus and has no common name.
The type species was collected from soil in Trinidad and Tobago. It was isolated by R.W. Jackson and given the strain number CBS 153.58.
One BLAST analysis suggests that some of P. circinan’s closest relatives are Blakeslea spp., Choanephora spp., and Gilbertella spp. (Karthikeyan & Gopalakrishnan, 2014). Choanephora is classified in the same family. Maximum likelihood analysis using ITS sequenced data has established phylogenetic relationships between P. circinans, C. cucurbitarum, and C. infundibilifera. (Hyde et al., 2014)
Sporangiophores simple, arising directly from the substrate or the aerial hyphae. Sporangia more or less globose, columellate, wall brown and persistent, splitting into two or three sections along preformed sutures, multispored. Sporangiospores ellipsoid, longitudinally striate, bearing hyaline appendages at each pole. Zygospores with a smooth zygosporangial wall and a striate zygospore wall, brown, borne between tongs-like suspensors (Kirk, 1984). Few-spored sporangia not produced.
Type species:P. circinans
Species ofPoitrasia:
P. circinans(Naganishi & Kawakami) P.M. Kirk, 1984 (Mycologial Papers 152:52).
Poitrasia circinanswas described (asBlakeslea circinans) by Naganishi and Kawakami (1955), and it was included in the review of the Choanephoraceae by Hesseltine and Benjamin (1957). Mikawa (1979) included the taxon in his series on the Mucorales of Japan. Kirk (1977) studied the ontogeny of the zygospores ofChoanephora circinansand he (Kirk, 1984) transferred the species to a new monotypic genus,Poitrasia circinans.
Poitrasia circinans je grzib[6], co go nojprzōd ôpisoł H. Nagan. & N. Kawak., a terŏźnõ nazwã doł mu P.M. Kirk 1984. Poitrasia circinans nŏleży do zorty Poitrasia i familije Choanephoraceae.[7][8] Żŏdne podgatōnki niy sōm wymianowane we Catalogue of Life.[7]
Poitrasia circinans je grzib, co go nojprzōd ôpisoł H. Nagan. & N. Kawak., a terŏźnõ nazwã doł mu P.M. Kirk 1984. Poitrasia circinans nŏleży do zorty Poitrasia i familije Choanephoraceae. Żŏdne podgatōnki niy sōm wymianowane we Catalogue of Life.
