PORT PHILLIP BAY


Pycnogonid 

Achelia shepherdi Stock, 1973

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: Small, variably fused or articulated. General appearance circular or discoid, lateral processes touching or narrowly separated. Without dorsal transverse ridges.
ABDOMEN: Unsegmented.
EYES: Four.
PROBOSCIS: Barrel-shaped to spindle-shaped.
SCAPES: 1-segmented.
CHELAE: Vestigial, fingers atrophied.
PALPS: 7-9 segments; usually 8 segments.
OVIGERS: 10-segments in both sexes but larger in males; last three segments attached anaxially to the seventh, often doubled back over the eighth segment; compound spines present; no terminal claw, no apophysis on fifth segment.
LEGS: Eight. Propodal heel usually well developed.
TARSUS: shorter than propodus
AUXILIARY.CLAWS: present, usually long.
CEMENT GLANDS: Single dorsodistal femoral cement gland.

Taxonomy

Phylum:
Arthropoda
Subphylum:
Cheliceriformes
Class:
Pycnogonida
Order:
Pantopoda
Family:
Ammotheidae
Genus:
Achelia
Species:
shepherdi

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, unsegmented. Leg span about 5 mm.

Biology

While this species has been mainly collected from algae, particularly red and brown seaweed and seagrass, the association is most probably with epizoic hydroids which live on or near the algae. This species does not appear to be common in Port Phillip Bay with only a few records from the southern end. Males carry the eggs, holding them between body parts called ovigers that hang under the animal.

Habitat

On red and brown algae and seagrass, associated with hydroids, to depth of 50 m.

Seagrass meadows

Reefs

Distribution guide

Southern Australia.

Species Group

Sea spiders

Depth

Shallow (1-30 m)
Deep ( > 30 m)

Water Column

On or near sea floor

Max Size

5 mm

Commercial Species

No

Global Dispersal

Native to 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, Achelia shepherdi, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 29 Jun 2017, http://portphillipmarinelife.net.au:8098/species/6244

Text: creative commons cc by licence