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Revision of Genera Physoporella, STEINMANN and Oligoporella, PIA (Dasycladales, Green Algae)

STEINMANN (1903) established the genus Physoporella including forms with pear- to sphere-like branches closed into a calcareous sheath. PIA (1912) gave the new description of this genus including forms with pear-like (piriferous) branches arranged in whorls and closed into a calcareous sheath. In the same article he also established the genus Oligoporella, which is characterized by somewhat thicker trichophorous branches arranged in whorls. Soon afterwards PIA himself recognized problems concerning mutual differentiation of these genera, and supplemented the description of the genus Physoporella declaring that not all the pores should necessarily be closed, but it was important if closed pores existed at all (PIA 1920). In succeeding articles PIA (1925, 1927, 1935) expressed the need of repeated investigation of these two genera, and pointed out the possibility of their union. Many succeeding authors, especially HURKA (1967, 1969), also pointed out the differentiation problems, since opening or closing of the pores remained the only differentiation criterion, but nobody attempted to make the revision of the genera. On the other side many authors, PRATURLON (1963) as the first one, have recognized existence of two groups within genera Physoporella and Oligoporella: the group with single whorls and the group with double whorls. Different stratigraphical ranges (OTT 1972) and even different environments (ZORN 1974) have been ascribed to these groups. In this paper the presence of single or double whorls is considered as the main characteristic that separates the genera Physoporella and Oligoporella, because of its biological importance. On the other hand opening or closing of the pores is connected with degree of calcification and preservation of calcareous skeleton, which can be strongly influenced by environment and diagenesis, and therefore can not have significant taxonomical importance. As the type species Physoporella pauciforata (GÜMBEL) has single whorls and Oligoporella pilosa PIA double whorls, the diagnoses of the genera are changed as follows: Physoporella (STEINMANN 1903) emend.: Thallus cylindrical, seldom slightly claviform, with piriferous branches arranged in single whorls. Oligoporella (PIA 1912) emend.: Thallus cylindrical, seldom slightly claviform, with piriferous branches arranged in double whorls. Each double whorl consists of two very close whorls of branches. According to the changed diagnoses it was necessary to make a revision of all species of these two genera to determine their generic position. For this purpose the type-material from the Pia's collection was reexamined and its redocumentation and reinterpretation performed. In the genus Physoporella (STEINMANN) emend. the following species are included: Physoporella croatica HERAK 1958, Physoporella gemerica (BYSTRICKY 1962) n. comb., Physoporella heraki BYSTRICKY 1967 var. heraki BYSTRICKY 1967, Physoporella heraki BYSTRICKY 1967 var. tenuipora BYSTRICKY 1967, Physoporella jomdaensis FLÜGEL & MU 1982, Physoporella leptotheca KOCHANSKY-DEVIDÉ 1967, Physoporella lotharingica (BENECKE 1898) PIA 1930, Physoporella minutuloidea HERAK 1967, Physoporella pauciforata (GÜMBEL 1872) STEINMANN 1903 var. pauciforata BYSTRICKY 1964, Physoporella pauciforata (GÜMBEL 1872) STEINMANN 1903 var. sulcata BYSTRICKY 1962, Physoporella pauciforata (GÜMBEL 1872) STEINMANN 1903 var. undulata PIA 1935 and Physoporella prisca (PIA 1912) n. comb. In the genus Oligoporella (PIA) emend. the following species are included: Oligoporella cornuta (PIA 1935) nom. nov., Oligoporella dissita (GÜMBEL 1872) n. comb., Oligoporella intusannulata (HURKA 1967) n. comb., Oligoporella laevis (PRATURLON 1963) n. comb., Oligoporella minutula (GÜMBEL 1872) n. comb., Oligoporella pilosa PIA 1912 var. pilosa PIA 1935, Oligoporella pilosa PIA 1912 var. intusannulata PIA 1935, Oligoporella praealpina (PIA 1920) n. comb. and Oligoporella varicans (PIA 1935) n. comb. Species Oligoporella chia HERAK 1967 is transformed into the genus Neoteutloporella BASSOULLET et al. 1978. Oligoporella elegans ASSMAN ex PIA 1931 is considered a younger synonym of Physoporella prisca (PIA 1912) n. comb. ; Physoporella likana HERAK 1965 is considered a younger synonym of Teutloporella herculea (STOPPANI 1857) PIA 1912 ; Oligoporella pilosa var. physoporelloidea PIA 1940, Oligoporella pilosa var. subvaricans PIA 1935 and Physoporella pauciforata var. variabilis ZANIN BURI 1965 are considered younger synonyms of Oligoporella pilosa PIA 1912 var. pilosa PIA 1935 ; Oligoporella serripora PIA 1912 is considered a younger synonym of Physoporella pauciforata (GÜMBEL 1872) STEINMANN 1903 var. pauciforata BYSTRICKY 1964 ; Physoporella praealpina PIA 1912 var. sulcata KOTANSKI & ^ATALOV 1973 is considered illegitimate due to the lack of the holotype. Physoporella karrerioidea (PIA 1935) is transformed into the new genus: Ardeiporella n. gen.: Thallus cylindrical with thick calcareous skeleton and narrow central cavity. Verticillate branches each consisted of narrow proximal part ("neck"), distinctly widened middle part ("head") and elongated distal part, which slightly thin toward the end ("bill").

green algae; Dasycladales; taxonomy

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