PORT PHILLIP BAY


Pycnogonid 

Nymphopsis bathursti Williams G, 1940

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. Strigilis variably developed but generally absent. 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: Unsegmented, compound spines on trunk and appendages.
ABDOMEN: Tall, spinous.
PROBOSCIS: Oval, elongate.
SCAPE: 1 or 2 segments distally flared.
CHELA: fingers smooth, well-developed or atrophied. Recessed into distal flare of scape.
PALPS: Usually 9 segments, exceptions 8 or10.
OVIGERS: 10-segmented both sexes; terminal claw not present; segments 8-10 carried anaxially on seventh, few compound spines. Apophysis absent
LEGS: Dorsodistal femoral cement gland tube present.
TARSUS: Shorter than propodus.
AUXILIARY CLAWS: present.
CEMENT GLAND: dorso-distal tube on femur.
GENITAL PORES: Male, on genital spur on ventral surface of coxa 2 of legs 3 & 4. Female ventral surface of coxa 2 of all legs.

Taxonomy

Phylum:
Arthropoda
Subphylum:
Cheliceriformes
Class:
Pycnogonida
Order:
Pantopoda
Family:
Ammotheidae
Genus:
Nymphopsis
Species:
bathursti

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 or more eyes. Eight segmented walking legs attached to the sides of the trunk. Tall and spinous abdomen behind trunk. Leg span about 1 cm.

Biology

These sea spiders are sometimes covered in sand and shell fragments, which suggests some individuals seek refuge in or on sand. Some of the larvae are unusual because they have a wide paddle-like extension (lamella) on some of the leg spines, perhaps an indication that they live in the plankton as they develop into adults. It is known know if this is a characteristic of all larvae in this genus group. More than one species is almost certainly represented in specimens assigned to this species in Australian waters. Males carry the eggs, holding them between body parts called ovigers that hang under the animal.

Habitat

Associated with seaweed and seagrass, possibly on sand, to depth of 25 m.

Soft substrates

Reefs

Seagrass meadows

Distribution guide

Southern Australia, excluding Tasmania. In central and eastern Victoria.

Species Group

Sea spiders

Depth

Shallow (1-30 m)

Water Column

On or near sea floor

Max Size

1 cm

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, Nymphopsis bathursti, in Taxonomic Toolkit for marine life of Port Phillip Bay, Museum Victoria, accessed 23 Nov 2017, http://portphillipmarinelife.net.au:8098/species/6257

Text: creative commons cc by licence