Dugesia
Dugesia is a genus of freshwater planarians in the family Dugesiidae triclads and the type genus of this family. These common flatworms are found in freshwater habitats of Africa, Eurasia, and Australia. Dugesia is best known to non-specialists because of its regeneration capacities.
Description
Dugesia species have an elongated body with a slightly triangle-shaped head. They often have grey, brown, or black dorsal color, whereas the ventral surface is usually paler. These animals have a couple of eyes constituted by a multicellular pigmented cup with many retinal cells to detect the amount of light in the nearby environment. Sometimes they present supernumerary eyes. At the anterior part of the body, behind the eye level, they have a pair of structures called auricles that give the triangle look to the 'head' and allow them to detect the intensity of water current. These auricles are free of pigment and rhabdites. Each side of the anterior margin of the head has between 5 and 10 shallow sensory fossae, their number depending on the species or the individual. The sensory fossae and the auricle grooves are supplied with many nerve endings.The digestive system of Dugesia contains a central, non-pigmented tubular pharynx. Like the other triclads, the gut consists of three branches, one anterior and two posterior. Each branch consists of caeca, which deliver the nutrients to the body. The gut lacks a separate opening for waste excretion.
The subepidermal musculature of Dugesia is divided into four layers.
In Dugesia the ovaries are ventrally situated, they start just behind the brain, usually at the level of the fourth intestinal branch. The bursal canal runs on the right side of the copulatory apparatus and above the atrium. Like some Neppia species, species of Dugesia have a third layer of longitudinal musculature over the vaginal area of the bursal canal. This feature is not present in other triclads. Another feature shared with Neppia is the presence of a glandular area at the transitional area between the seminal vesicle and the ejaculatory duct, although in Dugesia these glands are concentrated at the diaphragm, a structure not present in any other genera. Ball proposed that the presence of this glands was a synapomorphy of Dugesia and Neppia. The absence of these glands in some Neppia species is thought to be a secondary loss.
Reproduction
Species of Dugesia are hermaphrodites. Many species can reproduce both sexually and asexually.Phylogeny and taxonomy
Dugesia species lack enough morphological characters to recover the phylogenetic relation between them. The few available characters often contradict each other when a morphological phylogeny is attempted. Dugesia species are identified by the combination of diagnostic characters instead of different apomorphies. Over 130 species within the genus Dugesia have been described.Phylogeny
Phylogenetic tree including five dugesiid genera after Álvarez-Presas et al., 2008:Molecular phylogeny of 13 Dugesia species after Lázaro et al., 2009:
Molecular phylogeny of Dugesia species after Solà et al., 2013:
Species
The following species are currently recognised in the genus Dugesia:- Dugesia absoloni
- Dugesia aconcinna
- Dugesia adunca
- Dugesia aenigma
- Dugesia aethiopica
- Dugesia afromontana
- Dugesia ancoraria
- Dugesia andamanensis
- Dugesia annandalei
- Dugesia arabica
- Dugesia arcadia
- Dugesia ariadnae
- Dugesia artesiana
- Dugesia astrocheta
- Dugesia aurea
- Dugesia austroasiatica
- Dugesia bactriana
- Dugesia bakurianica
- Dugesia batuensis
- Dugesia benazzii
- Dugesia bengalensis
- Dugesia biblica
- Dugesia bifida
- Dugesia bijuga
- Dugesia borneana
- Dugesia brachycephala
- Dugesia brigantii
- Dugesia burmaensis
- Dugesia bursagrossa
- Dugesia capensis
- Dugesia chichkovi
- Dugesia circumcisa
- Dugesia constrictiva
- Dugesia corbata
- Dugesia crassimentula
- Dugesia cretica
- Dugesia damoae
- Dugesia debeauchampi
- Dugesia deharvengi
- Dugesia didiaphragma
- Dugesia dubia
- Dugesia ectophysa
- Dugesia effusa
- Dugesia elegans
- Dugesia etrusca
- Dugesia fissipara
- Dugesia foeni
- Dugesia fontinalis
- Dugesia gemmulata
- Dugesia golanica
- Dugesia gonocephala
- Dugesia gonocephaloides
- Dugesia hepta
- Dugesia hoernesi
- Dugesia hoidi
- Dugesia hymanae
- Dugesia iheringii
- Dugesia ilvana
- Dugesia improvisa
- Dugesia indica
- Dugesia indonesiana
- Dugesia insolita
- Dugesia iranica
- Dugesia izuensis
- Dugesia japonica
- Dugesia krishnaswamyi
- Dugesia lamottei
- Dugesia lanzai
- Dugesia lata
- Dugesia laurentiana
- Dugesia leclerci
- Dugesia leporii
- Dugesia libanica
- Dugesia liguriensis
- Dugesia lindbergi
- Dugesia machadoi
- Dugesia maculata
- Dugesia maghrebiana
- Dugesia majuscula
- Dugesia malickyi
- Dugesia mariae
- Dugesia mertoni
- Dugesia michaelsoni
- Dugesia microbursalis
- Dugesia milloti
- Dugesia minotauros
- Dugesia mirabilis
- Dugesia modesta
- Dugesia monomyoda
- Dugesia montana
- Dugesia musculosa
- Dugesia myopa
- Dugesia naiadis
- Dugesia nannophallus
- Dugesia nansheae
- Dugesia neumanni
- Dugesia nonatoi
- Dugesia notogaea
- Dugesia novaguineana
- Dugesia parasagitta
- Dugesia patula
- Dugesia pendula
- Dugesia polyorchis
- Dugesia postica
- Dugesia precaucasica
- Dugesia pustulata
- Dugesia rincona
- Dugesia ryukyuensis
- Dugesia saccaria
- Dugesia sacatta
- Dugesia sagitta
- Dugesia schauinslandi
- Dugesia seclusa
- Dugesia semiglobosa
- Dugesia siamana
- Dugesia sicula
- Dugesia similis
- Dugesia sinensis
- Dugesia subtentaculata
- Dugesia superioris
- Dugesia tamilensis
- Dugesia tanganyikae
- Dugesia taurocaucasica
- Dugesia transcaucasica
- Dugesia tubqalis
- Dugesia tumida
- Dugesia uenorum
- Dugesia umbonata
- Dugesia venusta
- Dugesia verrucula
- Dugesia vestibularis
- Dugesia wytegrensis
- ''Dugesia xeropotamica''