227 ACTA ZOOLOGICA BULGARICA Acta zool. bulg., 59 (3), 2007: 227-240 Taxonomic Review of the Genus Centropyxiella (Rhizopoda: Filosea) with Data on its Biology and Geographical Distribution Vassil Golemansky 1* , Milcho Todorov 1 1 Institute of Zoology, Bulgarian Academy of Sciences, 1, Tsar Osvoboditel Blvd., 1000 Sofia; Fax: +3592 9888 28 97; E-mails: Golemansky@zoology.bas.bg; mtodorov@zoology.bas.bg Abstract: The genus Centropyxiella VALKANOV, 1970 was erected as a result of investigation of marine and brackish interstitial habitats of the Black Sea littoral. Since then, ten species and varieties from many other seas and oceans around the world were described. In this paper we present a brief historical review and taxonomic status of all known Centropyxiella species. Recent studies on living animals of Centropyxiella arenaria VALKANOV, 1970 proved that the genus Centropyxiella is related to class Filosea LEIDY, 1879 and to family Psammonobiotidae GOLEMANSKY, 1974. Taxonomic revision of all Centropyxiella species and varieties described so far shows that one of them - C. haustorifera KORGANOVA, 1992 is considered nomen dubium and three of them: C. elegans VALKANOV, 1970, C. lucida var. minima CHARDEZ, 1972, and C. oopyxiformis CHARDEZ, 1977 are considered synonyms. Morphological description, summarized data on the geographical distribution and figures are presented for six valid species: C. arenaria VALKANOV, 1970, C. gibbula VALKANOV, 1970, C. gibbulina CHARDEZ and THOMAS, 1986, C. golemanskyi CHARDEZ, 1977, C. lucida GOLEMANSKY, 1971, and C. platystoma GOLE- MANSKY, 1981. Key words: Centropyxiella, Rhizopoda, taxonomy, biology, distribution * Corresponding author Introduction The genus Centropyxiella was erected by VALKANOV (1970). He found 3 new species of the genus (C. are- naria, C. elegans and C. gibbula) in underground water of sandy beaches at the Bulgarian Black Sea Coast and in brackish water from aquariums with marine algae. The descriptions of these species were based on the morphology and measurement of emp- ty shells. They were illustrated either by schematic graphic drawings or by light microscope microphoto- graphs. VALKANOV (1970) emphasized that the form and structure of Centropyxiella’s shell were close to those of freshwater genus Centropyxis, which inhab- ited brackish water as well. The only significant dif- ference is that the shell’s periphery in aperture area of the new genus is not invaginated. It is evaginated and forms a characteristic circular or oval funnel- like collar around the aperture. VALKANOV (1970) described genus Centropyxiella briefly as: “Schale plagiostom, bedeсt mit xenosomen. Sie ähnett der schale von Centropyxis. Zum Unterschied von letzerer Gattung ist der Rand des Pseudostoms in seiner ganzen Länge nach außen eingebogen”. One year later GOLEMANSKY (1971) found C. arenaria in underground water of the Pacific sandy