Buccal cavity in two parts, short anterior chamber at level of cephalic sensilla, narrow tubular part at least 25 µm long. Amphid placed over or very close to end of buccal tube. Male with two testes.
Type species: Rhynchonema cinctum Cobb, 1920
Valid species of Rhynchonema along with their type locality and habitat (Fig. 2).
Updated from Lorenzen 1975 and Bezerra et al. 2014.
Rhynchonema amakusanum Aryuthaka, 1989: Amakusa, Japan; intertidal zone and adjacent seagrass (Zostera marina Linnaeus, 1753) bed.
Rhynchonema ambianorum Boucher, 1974: Atlantic coast of France; fine sand from 5 m depth.
Rhynchonema brevituba Gerlach, 1953: Italy; sandy beach.
Rhynchonema cemae Bezerra et al. 2014: Olinda’s Isthmus, Pernambuco, Brazil; intertidal medium sand.
Rhynchonema ceramotos Boucher, 1974: Atlantic coast of France; fine sand from 5 meter depth.
Rhynchonema chiloense Lorenzen, 1975: South Chile; sand in the tidal area.
Rhynchonema cinctum Cobb, 1920: Salaverry, Peru; near low water line.
Rhynchonema collare Nicholas and Stewart, 1995: New South Wales, Australia; sandy ocean beaches.
Rhynchonema deconincki Vitiello, 1967: Atlantic coast of France; arenicola sand.
Rhynchonema dighaensis sp. nov.: Digha, West Bengal, Northern part of east coast of India. Study area is influenced by several fresh water inflows.(Present paper).
Rhynchonema dispar Gourbault, 1982: Guadeloupe, West Indies; sandy beach.
Rhynchonema falciferum Boucher, 1974: Atlantic coast of France; fine sand from 5 m depth.
Rhynchonema fossum Lorenzen, 1975: Santa Marta, Atlantic coast of Columbia, Southern Chile; steeper surf beach, at the top of outgoing waves, 5-10 m depth.
Rhynchonema gerlachi Vitiello, 1967: Europa Island, Mozambique Channel, Madagascar; marine sand.
Rhynchonema hirsutum (Hopper, 1961): Alabama, Atlantic Coast of USA, Gulf of Mexico; fine sand from 5 m depth.
Rhynchonema impar Lorenzen, 1975: Santa Marta, Atlantic coast of Columbia, Southern Chile; steeper surf beach, at the top of outgoing waves, 5-10 m depth.
Rhynchonema kikuchii Aryuthaka, 1989: Amakusa Shimoshima Island, Japan; intertidal zone and adjacent seagrass (Zostera marina Linnaeus, 1753) bed.
Rhynchonema longituba Gerlach, 1953: Italy; marine sandy beach.
Rhynchonema lyngei (Allgén, 1940) Gerlach, 1953: (Syn- Leptolaimus lyngei Allgén, 1940); Allgén (1940) found one female specimen from Northern Norway; Gerlach (1953 b) recorded from brackish water in Finland from fine sand of 1m depth, later found from sublittoral coarse sand in Kiel Bay.
Rhynchonema megamphidum Boucher, 1974: Atlantic coast of France; fine sand from 5 m depth.
Rhynchonema moorea Boucher, 1974: Society Island, Moorea Lagoon, Central Pacific; littoral coral sand.
Rhynchonema ornatum Lorenzen, 1975: Atlantic coast of Columbia; exposed sandy beach.
Rhynchonema quemer Boucher, 1974: Atlantic coast of France; fine sand from 5 m depth.
Rhynchonema scutatum Lorenzen, 1972: Southern North Sea; fine sand from a depth of 25 m.
Rhynchonema semiserratum Lorenzen, 1975: Pelluco at Puerto Montt, Southern Chile; extensive coarse sad flats near low water line.
Rhynchonema separatum Lorenzen, 1975: Chiloe Island, Sothern Chile; coarse sand beach in the lowest tide range.
Rhynchonema sieverti Gourbault, 1982: Guadeloupe, West Indies; coral sand.
Rhynchonema subsetosum Murphy, 1964: Oregon, Pacific coast of USA; sand from mid tide region.
Rhynchonema tomakinense Nicholas and Stewart, 1995: New South Wales, Australia; sandy ocean beaches.
Rhynchonema tremendum Lorenzen, 1975: Chiloé Island, Southern Chile; coarse sand near the low water line from a depth of 10–20 cm.
Rhynchonema veronicae Bezerra et al. 2014: Olinda’s Isthmus, Pernambuco, Brazil; intertidal medium sand.
Rhynchonema xiamenensis Huang & Liu, 2002: Xiamen Island, Fujian, China; low intertidal sandy beach.