PORT PHILLIP BAY


Pycnogonid 

Ammothella biunguiculata (Dohrn, 1881)

View scientific description and taxonomy

Scientific Details

Family level characters.
TRUNK: Variably fused or articulated. Often compact and almost circular in outline.
SCAPE: 1or 2-segmented or absent.
CHELA: fingers generally reduced in adults but maybe chelate, atrophied or absent.
PALPS: 1-10 segments, usually 8-9 segments. Present in both sexes.
OVIGERS: 3-10 segments, both sexes but larger in males. No terminal claw. In some genera the number of oviger segments is fewer in the female. No apophysis. Terminal spines are compound.
LEGS: Eight only. Propodal heel usually well developed. Auxiliary claws present or absent. Dorsodistal femoral cement glands present.

Genus level characters.
TRUNK: Moderately elongate. Segmented, with few exceptions smooth, without ridges. Dorsal processes sometimes present. Lateral processes variably separated, sometimes touching.
PROBOSCIS: oval, inflated
ABDOMEN: frequently articulated at base.
EYES: four
PROBOSCIS: Typically large, bulbous.
SCAPES: 2-segmented.
CHELAE: Atrophied in adults.
PALPS: 9- segmented.
OVIGERS: 9-10 segments both sexes. No terminal claw; compound spines; no apophysis.
LEGS: Male with dorsodistal cement gland. Main claw absent in one species.
TARSUS: Shorter than propodus.
AUXILIARY CLAWS: Present (one exception).

Taxonomy

Phylum:
Arthropoda
Subphylum:
Cheliceriformes
Class:
Pycnogonida
Order:
Pantopoda
Family:
Ammotheidae
Genus:
Ammothella
Species:
biunguiculata

Other Names

  • Sea spider

General Description

Body with proboscis projecting outward from front, with the mouth at the tip. Central body (trunk) behind the proboscis, with a raised, rounded area (tubercle) bearing four eyes. Eight segmented walking legs attached to the sides of the trunk. Small abdomen behind trunk, not articulated at base. Leg span about 15 mm.

Biology

This is a cosmopolitan species, occurring in waters around the globe. In Victoria, all records are from beneath rocks and boulders typically associated with a silt substrate. Males carry the eggs, holding them between body parts called ovigers that hang under the animal.

Habitat

In sheltered areas, occasionally in tide pools along our exposed coastline, to depth of 2 m.

Reefs

Coastal shores

Distribution guide

Worldwide. Southern Australia, including western and central Victoria.

Species Group

Sea spiders

Depth

Shore (0-1 m)
Shallow (1-30 m)

Water Column

On or near sea floor

Max Size

15 mm

Commercial Species

No

Global Dispersal

Recorded in Australia.

Conservation Status

  • DSE Advisory List : Not listed
  • EPBC Act 1999 : Not listed
  • IUCN Red List : Not listed

Author

article author Staples, D.

David Staples is a consultant with expertise in pycnogonid taxonomy.

citation

Cite this page as:
Staples, D., 2011, Pycnogonid, Ammothella biunguiculata, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 27 Jun 2025, http://136.154.202.208:8098/species/6247

Text: creative commons cc by licence