Marine Flora and Fauna of Hong Kong and Southern China IV

New benthic nemerteans from Hong Kong

The Marine Flora and Fauna ofHong Kong and Southern China IV (ed. B. Morton). Proceedings of the Eighth International Marine Biological Workshop: The Marine Flora and Fauna of Hong Kong and Southern China, Hong Kong, 2-20 April 1995. Hong Kong: Hong Kong University Press, 1997. NEW BENTHIC NEMERTEANS FROM HONG KONG Ray Gibson School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, U.K. ABSTRACT Three species of benthic anoplan nemerteans, including one new genus, are described from the Marine Reserve at Cape d'Aguilar, Hong Kong. These are the palaeonemertean Hubrechtella alba sp. nov. and the heteronemerteans Micconemertes orientalis gen. et sp. nov. and Micrura achrostocephala sp. nov. INTRODUCTION Thirty species of nemerteans have so far been recorded from the Hong Kong region (Stimpson 1855, 1857; Humes 1942; Gibson 1990a; Gibson and Sundberg 1992), although six of these, established entirely on the basis of their external features, are either invalidated or identified as nomina dubia by Gibson (1995). Humes (1942) record of the brachyuran egg predator Carcinonemertes mitsukurii Takakura, 1910, is of uncertain validity. The nemertean fauna of Hong Kong is both rich and diverse (Gibson 1990a), Gibson and Sundberg (1992: 97) noting that 'we have at least 100 species in our collections yet to be described.' The present paper reports on three species which were collected from the Marine Reserve at Cape d'Aguilar, south-eastern Hong Kong, during April 1995. MATERIALS AND METHODS The nemerteans described were all collected within the boundaries of the Cape d' Aguilar Marine Reserve during April 1995. Many were obtained sublittorally, others were collected intertidally by Professor Christer Erseus (C.E. in Table I which lists the various locations within the Cape d'Aguilar Marine Reserve where specimens were obtained). The nemerteans were examined alive after anaesthetization in 7.5% MgC12 before being fixed in Bouin's fluid made up in seawater. Histological studies have been made on 6 ~ sections of animals embedded in 56°C m.p. paraffin wax and stained by Crandall's modified Mallory trichrome technique. Type specimens are deposited in the Liverpool Museum, William Brown Street, Liverpool L3 8EN (LIV). 10 R. GIBSON Table 1 Locations within the Cape d'Aguilar Marine Reserve, cited in text, from where specimens of the nemerteans were obtained during 1995. A query in a column indicates that appropriate data were not obtained. Site Date C.E. Site 1 2 April C.E. Site 2 6 April C.E. Site 3 6 April Dive Site 2 5 April Dive Site 3 5 April Dive Site 6 5 April Dive Site 10 6 April Dive Site 13 7 April Dive Site 14 7 April Dive Site 16 7 April Dive Site 17 8 April Dive Site 18 8 April Dive Site 20 8 April Dive Site 21 8 April Dive Site 22 8 April Dive Site 23 9 April Dive Site 24 9 April Dive Site 25 9 April Dive Site 26 10 April Dive Site 27 10 April Dive Site 28 10 April Dive Site 29 11 April Dive Site 30 11 April Depth m Mid-shore Lower shore Lower shore 17-18 8 19.5 ? 7 2 16 7 22 ? ? ? 1-2 25 13 17 10 14 16 6.5 Description Mixture of gravel and sand in a rock pool In fairly coarse mixture of shell, sand, gravel and pebbles by slipway. Under stones in coarse sand and gravel. Flocculent shell sand with lots of silt. Silt and shell hash, very black as if anaerobic but did not smell too bad. Fairly compacted but unsorted mixture of shell fragments, sand, mud, clay and gravel; associated fauna included caprellids, cumaceans, echinoids, ophiuroids, polychaetes, oligochaetes, amphipods, ostracods, nematodes and bivalves. Coarse shell sand. Heterogeneous sand, very poorly sorted. Very coarse shell gravel. Very soft silt and shell sand. Silty shell sand. Silt and clay with some shell debris and pebbles. ? Silt and heterogeneous shell sand. Silt plus fine to medium shell sand. Among coralline algae and Megabalanus volcano. Silt and heterogeneous shell sand and shell gravel. Coarse shell sand, shell gravel and pebbles. Coarse shell sand with some silt. Silt and medium shell sand. Lobster Bay, silt, clay and fine shell sand. Clay, silt and coarse shell sand. Silt and heterogeneous shell sand. DESCRIPTIONS OF THE SPECIES ANOPLA PALAEONEMERTEA HUBRECHTIDAE BUGER, 1892 Hubrechtella Bergendal, 1902 Diagnosis: Palaeonemerteans with two body wall muscle layers consisting of outer circular and inner longitudinal fibres; brain and lateral nerve cords situated...