Pycnogonid Classification

Traditionally, pycnogonids were classified as the most primitive chelicerates and their relationships with other chelicerate taxa had been considered to be problematical at best. Recent research has demonstrated that pycnogonids are closely related to mites and ticks and they are now considered to be an order of Arachnids, Order Pycnogonida (Bain, in press). Within the pycnogonida, there are currently a number of different classification schemes, most with seven to nine different families. The most commonly used classification schemes are those of Stock (1994) and Hedgpeth (1947, 1982) each with eight families. Arnaud and Bamber (1987), a recent summary of pycnogonid biology, use a combination of these two classification schemes. There are currently 86 pycnogonid genera and at least a thousand species (Bain, 1992). There is no recent published species catalog for the group.

Table 1
A Comparison of Current Pycnogonid Classifications
(modified from Bain, in press)

Hedgpeth (1947, 1982); King (1973) Stock (1994) Arnaud & Bamber (1987)
Nymphonidae Nymphonidae Nymphonidae
Pallenidae1 Callipallenidae Callipallenidae
Phoxichilidiidae Phoxichilidiidae2 Phoxichilidiidae
Endeidae Endeidae
Ammotheidae Ammotheidae3 Ammotheidae3
Colossendeidae Colossendeidae Colossendeidae
Pycnogonidae Pycnogonidae Pycnogonidae
Austrodecidae4 Austrodecidae5
Rhynchothoracidae Rhynchothoracidae

1 Pallene is a preoccupied genus name (Flynn 1929, p. 252). Most species of Pallene have been changed to Callipallene and the family name changed to Callipallenidae.
2 Includes the genus Endeis
3 Includes the family Tanystylidae
4 Contains only the genus Austrodecus
5 Contains both Austrodecus and Pantopipetta

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