A new freshwater heteronemertean from the Zhujiang (Pearl River), People's Republic of China

Abstract

A new genus and species of freshwater heteronemertean, Amniclineus zhujiangensis, from the Zhujiang (Pearl River), People's Republic of China, is described and illustrated. The species is placed in the family Lineidae along with the existing freshwater heteronemertean taxa, with which its anatomy is compared.

Enzyme electrophoresis, genetic identity and description of a new genus and species of heteronemertean (Nemertea, Anopla) from northwestern Spain and North Wales

“…sesses a 'palaeotype' organisation, and on this Some 29 heteronemertean genera are known or Table 4. Some of the morphological features commonly used for distinguishing between heteronemertean genera, summarised for those forms that are known to, or probably, possess a 'palaeotype' proboscis; data from Gibson (1990b), Gibson & Qi Sang (1991) Iwata (this volume) and Riser (this volume suspected to possess a 'palaeotype' proboscis (Gibson, 1985(Gibson, , 1990aGibson & Qi Sang, 1991; Iwata, this volume; Riser, this volume), although in a few (e.g., Tenuilineus) the proboscis is regarded as transitional to the 'heterotype' because it possesses a short additional outer longitudinal muscle layer just behind the proboscis insertion. Commonly several morphological features have been used as a means of distinguishing between the numerous heteronemertean genera and these are summarised for the 'palaeotype' group in Table 4.…”

“…8 = Blood system in foregut region developed into plexus ( + ) or consiting of only t < wo vesels running in parenchyma (0). a The foregut vascular plexus in Amniclineus(Gibson & Qi Sang, 1991) and Apatronemertes(Wilfert & Gibson, 1974) is intimately associated with components of the excretory system, the unusual arrangement in these taxa being interpreted as a consequence of their freshwater habits.…”

Potamostoma shizunaiense gen. et sp. nov. (Nemertea: Hoplonemertea: Monostilifera): a New Brackish-Water Nemertean from Japan

“…The Amphiporus and Tetrastemma species, which were reported from Sea of Okhotsk by Korotkevich (1977), are not found in salinities less than 18 psu (Table 1) and their excretory systems are restricted to the foregut region of the body. On the other hand, those euryhaline species, including Amniclineus zhujangensis Gibson and Qi, 1991, Hinumanemertes kikuchii Iwata, 1970, Sacconemertella lutulenta Iwata, 1970, Sacconemertopsis belogurovi Chernyshev, 1991, S. olivefera Iwata, 1970, and the present species, which live in salinities fluctuating down to 1-6 psu, possess excretory systems extending throughout most of the body. These findings suggest the critical salinity, where nemerteans have to develop their excretory system throughout the body for survive, would likely to be between 6-18 psu.…”

“…The specific epithet is derived from the name of the River Shizunai by adding the Latin adjectival suffix -ense (= belonging to). Diagnosis : Monostiliferous hoplonemerteans with rhynchocoel reaching to posterior end of body; rhynchocoel musculature in two separate layers; proboscis anterior chamber with three muscle layers (outer and inner circular, middle longitudinal); body-wall musculature with diagonal layer, longitudinal layer anteriorly divided by posterior extensions of cephalic glands; pre-cerebral septum absent; cephalic retractor muscles derived from outer portion of longitudinal musculature; oesophagus opening into rhynchodaeum just behind proboscis pore; intestinal caecum with two anterior pouches and lateral diverticula; blood system very well developed, with single vascular plug; cerebral ganglia with neither inner neurilemma nor neurochord cells; lateral nerve cords without accessory nerves but with myofibrillae; peripheral nervous system well developed; single apical organ present, cephalic glands well developed, extending behind brain, sub-muscular glands present; cerebral organs close in front of brain; excretory system well developed, extending Gibson and Qi, 1991 Found in the lower part of the Pearl River, People's Republic of China, mostly in freshwater conditions (<0.5 psu) but the habitat occasionally reaches a maximum salinity of about 10.9 psu (Gibson and Qi, 1991).…”

“…On the other hand, there have been only a few reports on species inhabiting in those environments, where the salinity fluctuates rapidly, like in mangrove swamps, river mouths or brackish-lakes (e.g. Gibson and Qi, 1991;Iwata, 1970;Moore and Gibson, 1981) (Table 1).…”