Gamsiella, A New Subgenus of Mortierella (Mucorales: Mortierellaceae)

-M ortierella multidivaricata is described and placed in a new subgenus, Gamsiella, of M ortierella. It is distinguished from species of subgenus M ortierella in having repeatedly divaricately branched sporangiophores. Large numbers of sporangiola develop simultaneously on slender, attenuate pedicels arising from the ultimate branches of the sporangiophore. The sporangiole of M. multidivaricata forms two subglobose, finely sculpttued sporangiospores. Mostly terminal, globose, spiny chlamydospores are formed in slender, secondary, intraor extrahyphal hyphae that arise from living segments of the ageing aerial mycelium. Classification of the Mortierellaceae is summarized briefly. The type and only known strain of M. multidivaricata originated from a rotting stump in Moscow, USSR. The fungus being described here was isolated by Carmen Stoianovitch from detritus taken from a rotting stump in Sokolniki Park, Moscow, U.S.S.R., by L. S. Olive while he was attending the XIIth International Botanical Congress in Leningrad in July, 1975. Dr. Olive correctly recognized it as a probable member of the Mortierellaceae, and I am grateful to him for giving it to me for study. I received the isolate in October, 1975, and since that time it has been maintained in culture on a variety of media where it has shown no loss of vigor or capacity to sporulate after repeated transfer. The description of the new fungus has been prepared from cultures on YpSs agar (per liter of water: K2HP04 ·3H20, 1.3 g; MgS04 ·7H20, 0.5 g; yeast extract, 4 g; soluble starch, 15 g; agar, 15 g) and PYED (per liter of water: peptone, 1 g; dextrose, 0.5 g; yeast extract, 1 g; agar, 15 g) at a pH of ca. 6.5. M ortierella Coemans subgenus Gamsiella Benjamin, subgen. nov. Hyphae substratae tenues ramosae hyphis aeriis tenuibus ramosarum emittentes. Sporangiophora succesive hivel tridivaricate ramosa ex amplificationibus intercalaribus lateralibus hypharum aeriarum genita. Rami ultimi sporangiis terminalibus bisporis in pedicellis elongatis subtilibus attenuatis parientes. Sporangia noncolumellata; paries fugax. Species typica: Mortierella multidivaricata Benjamin. Substrate hyphae slender, branched, giving rise to slender, branched aerial hyphae that form intercalary, lateral enlargements which become sev-