Species accounts

Red haplognathia

Haplognathia ruberrima

FAMILY

Haplognathiidae TAXONOMY

Haplognathia ruberrima Sterrer, 1966, Swedish west coast.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Length to 0.138 in (3,500 pm); diameter 0.0051 in (140 pm); one of the largest gnathostomulids. Most specimens are uniformly brick red, reddish brown, or pink, owing to pigment granules in the epidermis. Rostrum (head) slender and pointed, without paired sensory bristles; posterior end uniformly rounded. Jaws solid, with large winglike apophyses and many sharp denticles; basal plate shieldlike, set with dorsal thorns. Sperm threadlike, with corkscrewlike head.

DISTRIBUTION

The most globally distributed species, found in Australia, Fiji, and Hawaii, as well as on both sides of the North Atlantic and the Mediterranean.

HABITAT

Like most gnathostomulids, prefers detritus-rich sand in shallow sublittoral areas.

BEHAVIOR

An animal that has been isolated from the sediments usually coils up by muscular action, then uncoils again by means of its cilia, often from both ends simultaneously, with the rostrum pulling forward and the posterior end pulling backward.

FEEDING ECOLOGY AND DIET

Seems to graze on fungal hyphae and bacteria adhering to sand grains.

REPRODUCTIVE BIOLOGY

Single egg is laid by rupture of the dorsal body wall. Egg then sticks to a sand grain until a fully ciliated hatchling 330 pm long emerges.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Gnathostomula

H Haplognathia ruberrima H Gnathostomula paradoxa H Austrognathia australiensis

No common name

Gnathostomula paradoxa

FAMILY

Gnathostomulidae TAXONOMY

Gnathostomula paradoxa Ax, 1956, Kieler Bucht (Kiel Bay), North Sea.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Length to 0.0394 in (1,000 pm), diameter to 0.00295 in (75 pm) Body colorless; rostrum rounded, headlike, set with paired sensory bristles; posterior drawn out into a short tail. Jaws hollow, with three rows of teeth; basal plate with paired lateral and rostral wings. Reproductive system with a cuticular bursa and a penis stylet. Sperm small, aflagellate, droplet shaped.

DISTRIBUTION North Sea.

HABITAT

Occurs in detritus-rich sand, straying into clean sand.

BEHAVIOR

Nothing is known.

FEEDING ECOLOGY AND DIET Grazes on attached microflora.

REPRODUCTIVE BIOLOGY

Nothing is known.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

No common name

Austrognathia australiensis

FAMILY

Austrognathiidae TAXONOMY

Austrognathia australiensis Sterrer, 2001, Lizard Island, Queensland, Australia.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Length to 0.0315 in (800 pm), diameter to 0.00315 in (80 pm). Body colorless, slender; head rounded, set with paired sensory bristles; posterior end pointed. Jaws hollow, with two rows of teeth; basal plate with pronounced median and a pair of lateral lobes. Bursa and penis without hard structures; sperm large, cone shaped, aflagellate.

DISTRIBUTION Queensland, Australia.

HABITAT

Occurs in detritus-rich sand near sea grass beds and patch reefs.

BEHAVIOR

Nothing is known.

FEEDING ECOLOGY AND DIET

Nothing is known.

REPRODUCTIVE BIOLOGY

Nothing is known.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Resources

Periodicals

Sterrer, W. "Gnathostomulida from the (Sub)tropical

Northwestern Atlantic." Studies on the Natural History of the Caribbean Region 74 (1998): 1-178.

-. "Gnathostomulida from Australia and Papua New

Guinea." Cahiers de Biologie Marine 42 (2001): 363-395.

Serensen, M. V., and Sterrer, W. "New Characters in the Gnathostomulid Mouth Parts Revealed by Scanning Electron Microscopy." Journal of Morphology 253 (2002): 310-334.

Wolfgang Sterrer, PhD

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