Unresolved name

Ptilohyale plumulosus

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Hyale plumulosa (Stimpson)

Allorchestes plumulosus Stimpson, 1857:79.

Hyale plumulosus.—Thorsteinson, 1941:55–56, pl. 1: figs. 10–15.

Hyale plumulosa.—J. L. Barnard, 1969b:138.—Bousfield, 1973: 155–156, pl. 44.2.

DISTRIBUTION.—Western Atlantic, Maine to North Carolina; Eastern Pacific, southern Alaska to southern California.

The Hyale grandicornis Complex

The grandicornis group of Hyale comprises species with an immense inner setule or seta on the dactyl of pereopods 1–5 close to the middle of the margin. The eyes are very large, dark, and oblatovate. Uropod 1 has the apicolateral spine on the peduncle either small or medium sized and the apicomedial spine also middle sized, in neither case is the spine enlarged. This eliminates H. longicornis (Haswell) from the discussion.

This discussion concerns only those species of the group in the Pacific Ocean, those having been described from Chile, New Zealand (2 species), Japan, Hawaii, California, and, now, the Galapagos Islands. The taxa are to be rectified herein nomenclaturally so that each is established at full specific level. This would appear to be the best way to treat these taxa until much more extensive exploration and study of morphs can be undertaken to determine whether certain clusters are better reduced to a subspecific level.

The first species described, Hyale grandicornis (Krøyer, 1845) from Chile, was redescribed by Stephensen (1949:33). It and Hyale thomsoni Hurley (formerly known as Hyale grandicornis forma thomsoni Hurley, 1957, here elevated to specific level) from New Zealand differ from other Pacific species in the presence of “fur” on pereopod 4, in the absence of a disjunct subapical spine on the ramus of uropod 3, and in the reduction or absence of the dorsal spination on the outer rami of uropods 1–2. Hyale grandicornis also has a sharply posteroventral lobe on pereopod 5 but this is unknown in H. thomsoni.

All other Pacific species lack “fur” on pereopod 4, have a rounded lobe on article 2 of pereopod 5, bear 2 or more dorsal spines on the outer rami of uropods 1–2 and have at least 1 disjunct proximal spine on the ramus of uropod 3.

The following species appear to form a group characterized by normal spacing of dorsolateral spines on the peduncle of uropod 1: Hyale novaezealandiae (Thomson, 1879, redescribed by Hurley, 1957, but formerly known as Hyale grandicornis forma novaezealandiae) from New Zealand, and Hyale bishopae J. L. Barnard, 1955a (formerly known as H. grandicornis bishopae in J. L. Barnard, 1970) from Hawaii. These two species are very difficult to separate but apparently differ in the castellations on the pereopodal dactyls and the presence of a supernumerary facial spine on the ramus of uropod 3 in H. novaezealandiae. Hyale rupicola (Haswell) (J. L. Barnard, 1974:54) is also indistinguishable from H. novaezealandiae as reflected in the following key.

The final group is characterized by the extreme discontiguity of dorsolateral spine 2 from spine 1 (apicalmost) on the peduncle of uropod 1: Hyale californica J. L. Barnard, 1969b (formerly known as H. grandicornis californica) from California, Hyale species (formerly identified as H. novaezealandiae by Iwasa, 1939) from Japan, and Hyale humboldti, new species, from the Galapagos Islands. These species differ among themselves in castellations on dactyls of pereopods and a supernumerary facial spine on the ramus of uropod 3 as shown in the key to follow.

The 7 species form a Rassenkreis divisible into 3 parts, between Chile and New Zealand, between New Zealand and Hawaii, and among Japan, California, and the Galapagos Islands. Study of collections from intermediate localities is now required to demonstrate the validity of these species.

Hyale species

Hyale novaezealandiae.—Iwasa, 1939:276–278, fig. 16, pl. 16 [not Thomson].

This speciman is not H. novaezealandiae and according to notes of the late C. R. Shoemaker (USNM files) is probably Hyale pugettensis (Dana), which is probably synonymous with Allorchestes japonica Stimpson. This taxon is included in the key to the species of the Hyale grandicornis complex as Hyale species.
bibliographic citation
Barnard, J. L. 1979. "Littoral Gammaridean Amphipoda from the Gulf of California and the Galapagos Islands." Smithsonian Contributions to Zoology. 1-149. https://doi.org/10.5479/si.00810282.271