Jassahartmannae Conlan, 1990

Conlan, Kathleen E., Desiderato, Andrea & Beermann, Jan, 2021, Jassa (Crustacea: Amphipoda): a new morphological and molecular assessment of the genus, Zootaxa 4939 (1), pp. 1-191 : 158-159

Jassahartmannae Conlan, 1990

( Table 13 , Fig. 104 )

Diagnosis.

Both sexes:

Mandibular palp: article 2, dorsal margin without a fringe of setae.

Maxilla 1: without a cluster of setae at the base of the palp article 1.

Gnathopod 1: basis, anterolateral margin with a row of short setae along its length which may be slender or spine-like; carpus without a single or small cluster of short setae at the anterodistal junction of the propodus.

Gnathopod 2: basis with a row of short setae along the anterolateral margin (setal lengths ±25% of the basis width); carpus and propodus, setae on the anterior margin short and simple (setal length <basis width).

Pereopods 5–7: propodus not expanded anteriorly.

Uropod 1: ventral peduncular spinous process underlying about 50% of the longest ramus.

Uropod 3: inner ramus without spines mid-dorsally (with only the single apical spine).

Telson: tip without apical setae (only the usual short setae at each dorsolateral cusp).

Thumbed male:

Antenna 2: large individuals without plumose setae on the flagellum and peduncular article 5.

Gnathopod 2: propodus, palmar defining spines produced on a ledge, present in both small and large thumbed males.

Adult female:

Antenna 2: without plumose setae on the flagellum and peduncular article 5.

Gnathopod 2: propodus, palm shallowly concave.

Remarks. There is an error in the key to species in Conlan (1990) (though the description is correct). The gnathopod 1 carpus lacks a seta or setae at the anterodistal junction with the propodus. There are only 16 specimens known so far from two collections listed in Conlan (1990), both from New Zealand. Four of these are thumbed males (three major form and one minor form). All males possessed palmar defining spines, suggesting that they may not lose them even if major form. Jassa hartmannae most closely resembles J. justi but they differ in the stonger spination of the propodus of pereopods 5–7, stouter antenna 2 and spinier basis of gnathopod 2 in J. justi than J. hartmannae ( Figs 92 , 104 ). Jassa justi also achieves twice the body length of J. hartmannae .

Figures

FIGURE 92. Jassa justi Conlan, 1990. Holotype, adult male, major form, 8.5 mm, AM P34953; allotype, female, 6.9 mm, AM P37920; paratypes, subadult male, 5.4 mm and juvenile male 4.2 mm, AM P37921. Garden Bay, Macquarie Island (54°29ʹS, 158°58ʹE), 20 November 1977, J. K. Lowry and D. S. Horning, colls., station MA-10, among mixed red and green algae on rocky bottom, -3 m (AM). All views lateral. Setae omitted from the gnathopod 2 profiles except for those around the thumb and spines of the males in order to landmark position changes with growth. Scale 0.1 mm. Illustration after Conlan (1990).

FIGURE 104. Jassa hartmannae Conlan, 1990. Holotype, adult male, major form, 4.5 mm, AM P34950. Senecio Pool, The Snares, New Zealand (48°07ʹS, 166°38ʹE), 6 January 1977, G. D. Fenwick, coll., from Lessonia variegata holdfast, 1.5 m depth (AM). Allotype, adult female, NMNH 235008; paratypes, adult male, minor form, 3.1 mm and juvenile male, 1.8 mm, NMNH 235009, St. Clair, Dunedin, New Zealand (45°50ʹS, 17°20ʹE), 25 January 1968, J. L. Barnard, coll., station E973 (J. L. Barnard station NZ-8), formalin wash of algae, especially of pterocladians or streblocladians, heavy turf (Gelidium-Bostrychia) and several specimens of Pyura sp. (NMNH). Setae omitted on the gnathopod 2 profiles except for those around the thumb and spines of the males in order to landmark position changes with growth. All views lateral. Scale 0.1 mm. Illustration after Conlan (1990).