Download Copy a link to this page Cite this record

Hypohelion P.R. Johnst. 1990

Scientific name record
Names_Fungi record source
Is NZ relevant
This is the current name
This record has descriptions
Show more

Click to collapse Details Info

Hypohelion P.R. Johnst. (1990)
Hypohelion P.R. Johnst. 1990

Click to collapse Biostatus Info

Present
New Zealand
Political Region

Click to collapse Nomenclature Info

P.R. Johnst.
P.R. Johnst.
1990
ICN
Hypohelion P.R. Johnst. 1990
genus
Hypohelion

Click to collapse Classification Info

Hypohelion

Click to collapse Descriptions Info

Hypohelion P.R. Johnst. 1990

Wang et al. (Myc progress 13: 781-789, 2014) described a new Hypohelion species from China. It differs from the concept of the genus as understood by Johnston et al. in inhabiting a dicotyledonous plant and in the ascomata having a well-developed lower wall. Wang et al. regarding the NZ and Chinese species as forming a monophyletic clade, but when additional taxa are included in the analysis, this relationship breaks down. The tree attached is an extract from a LSU analysis that includes the two Hypohelion spp., Coccomyces dentatus, C. lauraceus, Lophodermium tindalii, L. medium, L. brunneolum, and Terriera minus (some unpublished).

Hypohelion P.R. Johnst. 1990

An ascomycete fungus belonging to the family Rhytismataceae. Ascomata subcuticular, upper wall uniform in internal structure. In opened ascomata upper wall uniform in thickness, and without differentiated cells lining the ascomatal opening. Ascomata lacking a darkened lower wall. Paraphyses swollen, clavate.
Fungus ascophorus ad familiam Rhytismatacearum pertinens. Ascomata subcuticularia, paries superior structure interna indutus uniformi. Ascomatibus ruptis paries superior crassitudinis respectu uniformis, sine celluis dissimilibus in superficie exposita. Ascomata sin parie inferiors fusco. Paraphyses tumidae, clavatae.

Etymology: Hypo-; refers to Hypoderma, the genus from which H. scirpinum has been segregated. -helion = swamp or marsh dwelling; refers to the habitat of the species included in this genus.

Johnston (1988a, 1988b, 1989, 1990) discussed the unsatisfactory nature of currently accepted generic limits in the Rhytismataceae, and showed that, at least for nonconiferous species, an alternative is possible. Rather than using single characters chosen a priori as important, genera may be based on sets of several characters, which in this case are mostly associated with ascomatal structure and development.

The characters used to define Hypohelion and to distinguish it from other genera in the Rhytismataceae are:
1. Subcuticular ascomata.
2. The upper wall of unopened ascomata is homogeneous in structure, comprising dark brown, thick-walled, angular cells.
3. In opened ascomata the upper wall is more or less uniform in thickness.
4. The edge of the ascomatal opening is not lined with differentiated cells.
5. The ascomata lack a darkened lower wall.
6. The paraphyses are swollen at the apex.

Hypoderma, in the sense accepted by Johnston (1990), possesses only the first of the characters listed above, and the upper wall of the ascomata has thickened labia and a characteristic internal differentiation. Powell (1974) considered that vestiges of thickened labia, in the form of a medial keel, could be seen in the upper wall of the ascomata in many collections of H. scirpinum. My observations showed that although a keel-like ridge is often seen on unopened ascomata, this is due to a folding, rather than a thickening, of the ascomatal wall. It cannot be compared with the thickened labia characteristic of Hypoderma rubi and other species of Hypoderma.

Hypohelion scirpinum and H. parvum are morphologically and anatomically similar, and are also similar with respect to host preference. Both are found on Cyperaceae growing in swampy habitats. The same kind of relationship between ascomatal structure and host substrate was demonstrated for a group of Lophodermium, Lophomerum, and Meloderma spp. found on the closely related families Epacridaceae, Ericaceae, and Pyrolaceae (Johnston 1988b). This correlation between morphological and biological characters suggests that the character set used in this paper, and by Johnston (1990) for Hypoderma, may define rhytismataceous genera in a way which reflects natural relationships amongst these fungi.

Species typica: Hypohelion scirpinum (de Candolle:Fries) Johnston.

Click to collapse Taxonomic concepts Info

Hypohelion P.R. Johnst. 1990
Hypohelion P.R. Johnst. 1990
Hypohelion P.R. Johnst. 1990
Hypohelion P.R. Johnst. (1990)

Click to collapse Metadata Info

1cb1c7ed-36b9-11d5-9548-00d0592d548c
scientific name
Names_Fungi
1 January 2001
1 June 2012
Click to go back to the top of the page
Top