Jassaalonsoae 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 : 138-143

Jassaalonsoae Conlan, 1990

( Table 13 , Figs 88–91 )

Diagnosis.

Both sexes:

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

Maxilla 1: without a seta or setal cluster at the base of the palp article 1.

Gnathopod 1: basis, anterolateral margin with a row of short setae along its length; carpus with a cluster of moderately long setae at the anterodistal junction of the propodus (setal length about 1/3 the length of the anterior margin).

Gnathopod 2: basis with a row of setae along the anterolateral margin (at least some setal lengths>40% 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 1/3 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: without plumose setae on the flagellum and peduncular article 5.

Gnathopod 2: propodus, palmar defining spines not produced on a ledge, present in small thumbed males but absent in large thumbed males. In major males, the thumb is distally squared, the posterior margin sinuous. The dactyl is expanded close to the junction with the propodus but is not centrally toothed. Minor form males have a short, squared thumb and a dactyl tooth. Subadult males have a small prethumb.

Adult female:

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

Gnathopod 2: propodus, palmsinuous.

Remarks. Jassa alonsoae , J. justi , J. fenwicki , J. ingens and J. hartmannae have a fringe of setae along the anterior margin of gnathopod 1 which may be robust and spine-like ( Figs 88–90 , 92 , 95 , 99 and 104 ). Jassa alonsoae differs from the others in having long setae on the basis of gnathopod 2 while the others have short setae similar to the basis of gnathopod 1. The row of setae on the gnathopod 1 basis is a distinctive character, which is only known for these Southern Hemisphere species. However, it is difficult to see on small animals and in J. ingens the setae do not run the full length in all animals ( Fig. 99 ). The other Southern Hemisphere species ( J. thurstoni , J. kjetilanna and J. gruneri ) seem to lack this fringe although there can be minute setae present ( Figs 93 , 96 and 102 ). The sinuous shape of the female’s gnathopod 2 palm is a feature of several (but not all) Southern Hemisphere species also ( J. alonsoae , J. thurstoni , J. fenwicki , J. kjetilanna , J. ingens and J. gruneri ) ( Figs 88 , 90 , 93 , 95 , 97 , 100 and 102 ). However, it is not unique to the Southern Hemisphere as the other two Southern Hemisphere species, J. justi and J. hartmannae have shallowly concave palms ( Figs 92 and 104 ) and the Northern Hemisphere J. myersi has a sinuous palm ( Fig. 85 ). The other Northern Hemisphere species (and the transhemispheric species) have more clearly concave palms.

Jassa alonsoae has been found more frequently than the other Southern Hemisphere species ( Fig. 11 ). It has a wide longitudinal range but has not been found south of 60°S. Specimens described by Stephensen (1949) as “ Jassa pulchella ” w ere examined (SNM) and are J. alonsoae . Conlan (1990) noted other mis-identifications. Monod (1926) mentioned a collection of “ J. falcata ” from the carapace of the spider crab Eurypodius latreilli in the Strait of Magellan. Although these specimens have not been seen, they may be Jassa alonsoae as this species has been collected in this area and it was found on spider crabs in a Falkland Island collection (AM P.31689). Monod’s illustration of the female gnathopod 2 resembles that of J. alonsoae . Stebbing’s (1888) “ Podocerus falcatus ” from Greenland Harbour, Kerguelen Island (Challenger station 149E) may also be J. alonsoae . Its sinuous gnathopod 2 palm suggests an indigenous Southern Hemisphere species and J. alonsoae is the only species known from Kerguelen Island ( Fig. 11 ). It is figured by Stebbing (1888) on Plate CXIX along with a female collected off the ship’s screw at Challenger station 142, off South Africa. Examination of this female (NHM) found that it is not J. alonsoae but J. marmorata . A description of the Challenger stations at http://www.19thcenturyscience.org/HMSC/HMSC-INDEX/index-linked.htm indicates that there was a second collection of Jassa at Kerguelen Island (Challenger station 149) but this was from the ship’s screw “after leaving the Cape ”. Examination of this collection found it to be also Jassa marmorata , indicating that this species was travelling with the ship.

Figures

FIGURE 11. Records of Southern Hemisphere species of Jassa. Red dot: identification confirmed by specimen examination; green dot: literature record (Supplementary Table S1) with identification not confirmed but judged likely to be this species; blue x: suspected or known to be on the hull or interior of a boat or ship.

FIGURE 85. Jassa myersi Conlan, 1990. Holotype, adult male, 5.8 mm, NHMLA 61-125.1; allotype, adult female, 4.4 mm, NHMLA 125.2; paratype, juvenile male, 3.7 mm, NHMLA 125.3. Coal Oil Point, Goleta, California, 2 July 1961, J. L. Barnard, coll., station 39-H-2, on rock surfaces in Phyllospadix zone, low intertidal zone. Adult male 1, 4.5 mm and subadult male, 5.1 mm, Coal Oil Point, Goleta, California, 2 July 1961, J. L Barnard, coll., station 39-K-1, on rock surfaces in Phyllospadix zone, low intertidal zone (NHMLA). Lateral views: whole body and uropods; dorsal view: telson; other views medial. Appendages are of the holotype unless noted otherwise. Scale 0.1 mm. Illustration after Conlan (1990).

FIGURE 88. Jassa alonsoae Conlan, 1990. Holotype, adult male, major form, 11.1 mm, ZMH K-33619; allotype, female, 9.8 mm, ZMH K-33635; paratype, adult male, minor form, 9.3 mm; paratype, large juvenile male, 12.8 mm; paratype, small juvenile male, 4.6 mm. South Georgia (54°30’58ʺS, 36°0’45ʺW), 16 January 1884, Deutsche Polar Commission, K. von den Steinen, coll., station 7804 (ZMH K-8017A). 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 89. Jassa alonsoae Conlan, 1990. Adult male, 10.0 mm. Puerto Deseado, Santa Cruz, Argentina, 26 October, 1981, G.M. Alonso, coll., A2020.0028 (CMN). Lateral view: gnathopod 2; other views medial. Scale 0.1 mm.

FIGURE 90. Jassa alonsoae Conlan, 1990. Adult female, 7.0 mm. Puerto Deseado, Santa Cruz, Argentina, 26 October, 1981, G.M. Alonso, coll., A2020.0028 (CMN). Lateral view: gnathopod 2; other views medial. Scale 0.1 mm.

FIGURE 91. Jassa alonsoae Conlan, 1990. Adult male, 10.0 mm. Puerto Deseado, Santa Cruz, Argentina, 26 October, 1981, G.M. Alonso, coll., A2020.0028 (CMN). Mouthparts. Frontal view: upper lip; other views medial. Scale 0.1 mm.

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 93. Jassa thurstoni Conlan, 1990. Holotype, adult male, major form, 5.9 mm, NHM 1969:761:2. Paal Harbour, Signy Island, South Orkney Islands (60°43ʹS, 45°36ʹW), 5 February 1965, M. H. Thurston, coll., station 44 (1218).Anchor dredge over mud at 20–25 m depth (NHM).Adult male 1, major form, paratype, 6.0 mm, NMCC-1082. Observation Bluff, Outer Islet, Signy Island, South Orkney Islands (60°42ʹ30ʺS, 45°35ʹ10ʺW), 14 September 1965, M. H. Thurston, coll., station 52 (2085), Agassiz trawl over gravel and sand, sand with some rock, algae on rocks, 20 m depth, NHM 1969:763:1 donated to CMN, accession no. IZ 1989-013. Adult female, paratype, 6.5 mm, NHM 1969:762:3. Berntsen Point–Bare Rock, Signy Island, South Orkney Islands (60°42ʹ10ʺS, 45°35ʹ30ʺW), 16 October 1964, M. H. Thurston, coll., station 50 (AT 76). Agassiz trawl over gravel and sand, some rocks with Desmarestia anceps and Phyllogigas grandifolius, 5–10 m depth (NHM). Lateral view: whole body, antenna 1 and gnathopod magnifications; medial view: uropod 3. Setae omitted from the gnathopod 2 profiles except for those around the thumb and spines of the male 1 in order to landmark position changes with growth. Scale 0.1 mm. Illustration after Conlan (1990).

FIGURE 95. Jassa fenwicki Conlan, 1990. Holotype, adult male, major form, 7.4 mm, AM P34951. Punui Bay, The Snares Islands, New Zealand (48°01′ S, 166°32′ E), 21 January 1977, G. D. Fenwick, coll. (AM).Allotype, subadult female, Cumberland Bay, South Georgia (54°14′ S, 36°28′ W), 9 May 1902, among algae, 1–2 m depth, type no. 3946 from lot no. 3015 (NRM). All views lateral. Setae omitted from the female gnathopod 2 profile. Scale 0.1 mm. Illustration after Conlan (1990).

FIGURE 96. Jassa kjetilanna Vader and Krapp, 2005. Adult male, major form, 6.5 mm. Choiseul Sound, East Falkland, 29 October 2003, A. and W. Vader, coll., from the lithodid crab Paralomis granulosa (Hombron & Jacquinot, 1846) at 20–30 m depth (TSZ Cr 19054). Lateral view: whole body and uropod 3; dorsal view: telson; other views medial. Scale 0.1 mm.

FIGURE 97. Jassa kjetilanna Vader and Krapp, 2005. Adult female, 5.0 mm; subadult male, 5.0 mm; juvenile male, 3.5 mm. Choiseul Sound, East Falkland, 29 October 2003, A. and W. Vader, coll., from the lithodid crab Paralomis granulosa (Hombron & Jacquinot, 1846) at 20–30 m depth (TSZ Cr 19054). All views medial. Scale 0.1 mm.

FIGURE 99. Jassa ingens (Pfeffer, 1888). Whole body: lectotype, adult male, major form, 22.1 mm, ZMH K-8017. Moltke- Hafen, Royal Bucht, South Georgia (54°30ʹ58ʺS, 36°0ʹ45ʺW), 16 Januarly 1884, Deutsche Polarstation 1882/83, K. Von den Steinen, coll. (ZMH). Adult male 1, major form, 20.3 mm and juvenile male, 10.6 mm, NHM 1969:705:9. Billie Rocks, Signy Island, South Orkney Islands (60°42ʹS, 45°36ʹW), 5 March 1965, M. H. Thurston, coll., station 10 (97). SCUBA collection on vertical creviced rock with Lithothamnia, Desmarestia anceps, Ascoseira mirabilis, Iophon/Phyllophora, Porifera, Polyzoa, 1.9–2.2 m depth, IZ 1989-013 (CMN). Subadult male, 19.9 mm, NHM 1969:713:4. Billie Rocks, Signy Island, South Orkney Islands (60°42ʹS, 45°36ʹW), 27 February 1965, M. H. Thurston, coll., station 20 (512), SCUBA collection on rock inclined at 45–50°with overlying boulders and sand in crevices. Lithothamnia, Desmarestia anceps, Rhodophyceae, Polyzoa, 7.4–7.7 m depth (NHM). 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 1 mm. Illustration after Conlan (1990).

FIGURE 100. Jassa ingens (Pfeffer, 1888). Adult male, major form, 20.3 mm, NHM 1969:705:9. Billie Rocks, Signy Island, South Orkney Islands (60°42ʹS, 45°36ʹW), 5 March 1965, M. H. Thurston, coll., station 10 (97). SCUBA collection on vertical creviced rock with Lithothamnia, Desmarestia anceps, Ascoseira mirabilis, Iophon/Phyllophora, Porifera, Polyzoa, 1.9–2.2 m depth, IZ 1989-013 (CMN). Adult female, 19.2 mm, NHM 723:7, Factory Cove–Berntsen Point, Signy Island, South Orkney Islands (60°42ʹS, 45°36ʹW), 15 April 1964, M. H. Thurston, coll., station 46 (1929). Agassiz trawl close inshore over boulder slopes with Desmarestia anceps, Phyllogigas grandifolius and Rhodophyceae dominant, 6–14 m depth, IZ 1989-013 (CMN). Lateral view: male uropod 3; medial views: female gnathopod 2 and uropod 3. Scale 0.1 mm.

FIGURE 102. Jassa gruneri Conlan, 1990. Holotype, juvenile male, 2.1 mm, NMCC 1987-1077; allotype, adult female, 3.2 mm, NMCC 1987-1078. Hobart Harbour, Tasmania (42°50ʹS, 147°20ʹE), 8 November 1978, G. Edgar, coll., SCUBA, algal washes, 3–5 m depth, 1978-287 (CMN). Lateral views. 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).