A monograph of the Dimarcusidae (Platyhelminthes, Seriata, Tricladida)

Abstract

The triclad family Dimarcusidae contains the species Rhodax evelinae, Opisthobursa mexicana, O. josephinae, Balliania thetisae and Mitchellia sarawakana. A comprehensive description is given of each of these species, covering external features, alimentary system, reproductive system, life cycle, ecology and distribution. Postulated apomorphies of the Dimarcusidae are (1) a penis bulb with gland cells, (2) horizontal orientation of female genital duct or bursal canal, combined with a dorsal opening of the common oviduct or diverticulum and (3) location of the ovaries at some distance posterior to the brain. The genera Rhodax, Opisthobursa and Mitchellia form a monophyletic group, the sistergroup being B. thetisae. The genera Rhodax and Opisthobursa share a sistergroup relationship. The Dimarcusidae should not be classified among the Maricola, Terricola or Paludicola. The family represents a fourth lineage within the Tricladida and is more closely related to the Paludicola and Terricola than to the Maricola.

Evolutionary history of the Tricladida and the Platyhelminthes: an up-to-date phylogenetic and systematic account

“…Concerning their phyletic position within the Tricladida, he found many features inconsistent with its belonging to the Maricola (as initially proposed for four of the five species). Sluys (1990) suggested a closer relationship to the Paludicola than to the Maricola, due to the fact that the Cavernicola share one of the three apomorphies of freshwater triclads. However, at that time, the Terricola and the Paludicola were still considered to be independent sister groups; under the current Continenticola hypothesis, Sluys' proposal of a closer affinity of the Cavernicola to freshwater planarians could point to the inclusion of the Cavernicola within continenticolans.…”

“…This division received a taxonomic rank (that varied between sub-and infraorder) and has been used since by all taxonomists, though a doubt was cast on the phylogenetic validity of these ecological groupings. Sluys (1990) proposed a fourth clade, the Cavernicola, grouping five species (belonging to four genera); four of them had been formerly assigned to the Maricola but with apparent closer affinities to the Paludicola. The systematic and phylogenetic relationships of these groups have been discussed on the basis of morphological and ultrastructural characters by Ball (1981), Sopott-Ehlers (1985), and Sluys (1989a).…”

“…Based on morphological characters, they have been considered in some detail within the Maricola (Sluys 1989b), the Cavernicola (Sluys 1990) and the former Paludicola (Ball 1974 Suborder Cavernicola Sluys, 1990 Family Dimarcusidae Mitchell and Kawakatsu, 1972 Suborder Continenticola Carranza and al, 1998 Superfamily Planarioidea Stimpson, 1857…”

“…The systematics of this group remains open and in need of extensive morphological and molecular studies. Sluys (1990) defined the clade Cavernicola formed by five species (grouped into a single family, the Dimarcusidae) based on three morphological features related to the reproductive apparatus. Concerning their phyletic position within the Tricladida, he found many features inconsistent with its belonging to the Maricola (as initially proposed for four of the five species).…”

Estado do conhecimento dos macroturbelários (Platyhelminthes) do Brasil

“…As quatro infraordens são classificadas de acordo com esses ambientes: Maricola, eminentemente em águas marinhas costeiras, com poucas espécies em água doce ou estuarinas (Sluys 1989); Cavernicola, em água doce de ambientes abertos ou de cavernas e no lençol freático (Sluys 1990); Paludicola, tipicamente de ambientes abertos de água doce, e Terricola, no meio terrestre úmido Na recente avaliação do estado do conhecimento da biodiversidade brasileira (Lewinsohn 2006) para a elaboração de políticas futuras de manejo e conservação da biodiversidade, os turbelários, como os outros grupos, não foram tratados exaustivamente. No presente trabalho o nosso objetivo é complementar essa avaliação com informações mais completas sobre a diversidade dos macroturbelários.…”