Notopais spicata Hodgson, 1910

Merrin, Kelly L., 2004, Review of the deep­water asellote genus Notopais Hodgson, 1910 (Crustacea: Isopoda: Munnopsididae) with description of three new species from the south­western Pacific, Zootaxa 513, pp. 1-27 : 5-8

Notopais spicata Hodgson, 1910 ( Fig. 1 )

Notopais spicatus Hodgson, 1910: 70 –71, pl. 8, fig. 1.

Pseudarachna spicata .— Vanhöffen, 1914: 593, fig. 126.— Hale, 1937: 43 –45, figs 18–19.— Kussakin, 1967: 313 –314, fig. 54.

Ilyarachna spicata .— Wolff, 1962: 95.— Amar & Roman, 1974: 579 –580, fig. 11.

Echinozone spicata .— Schultz, 1976: 8 ­10, figs 3–4.

Pseudarachna vanhoeffeni .— Schultz, 1976: 13.

Echinozone quadrispinosa .— Brandt, 1990: 216, fig. 1 (part).

Material Examined.— Holotype. Female (3.0 mm), Winter Quarters, McMurdo Sound, Ross Sea, Antarctica, 77°49’0”S 167°7’4”E, 28 February 1902, inside 20­fathom line (36.6 metres), S.S. Discovery ( BMNH 1910.3.18.150).

Additional material.— Male (3.0 mm), Gauss Station, Davis Sea, Antarctica, 66°2’S 89°38’E, 12 August 1902 or 19 December 1902, 385 m, Gauss ( ZMHB 17739).

Description: Holotype. Body 2.3 times as long as greatest width (from spine to spine) of pereonite 2; widest at pereonite 2; cuticle not highly calcified, lightly setose. Cephalon smooth, with 2 dorsal spines; posterolateral margins rounded; ridge encompassing antennae with no extension. Pereonites 1–5 anterior margins each with 4 well­developed spines; anterolateral margins of pereonites 1–4 with spines, 5–7 rounded and smooth; pereonites 1–4 with pair of lateral, sub­marginal spines and each with pair of widely spaced, small, dorsal sub­lateral spines.

Antenna 1 broken; article 1 2.1 times as long as wide, dorsal surface concave, with 1 sub­marginal robust flagellate seta, distal margin with 1 flagellate robust and 1 broom seta, superior margin with 1 simple and 1 broom seta; article 2 0.4 times as long as article 1, 2.0 times as long as wide, distal margin with 1 robust flagellate seta; remaining articles all rectangular, length varying; article 3 with 2 simple setae; article 4 with 1 simple seta; article 6 with 1 distal aesthetasc. Antenna 2 broken, articles 1–2 squat, both wider than long; article 1 superior margin with 2 simple setae; article 2 1.2 times as long as article 1, distolateral angle with spine, terminal robust seta and inferior margin with 1 simple seta; article 3 1.0 times as long as article 1, distolateral angle with spine terminated with robust seta, inferior margin with 2 simple setae and distoinferior margin with 1 short robust seta, 2 flagellate robust setae (long) and 1 simple seta; article 4 small, 0.8 times as long as article 1, not ornamented.

Pereopod 1 basis 7.2 times as long as wide, inferior margin with 4 setae (2 SS, 1 distal RFS, 1 distal RS), lateral face with 3 setae (all SS); ischium 3.8 times as long as wide, inferior margin with 3 setae (all SS), lateral face with 2 setae (both SS); merus 1.3 times as long as wide, inferior margin with 4 setae (all SS), distosuperior margin with 1 seta (SS); carpus 3.8 times as long as wide, inferior margin with 2 setae (both long SS, in proximal half), superior margin with 3 setae (all SS, 1 distal); propodus 4.0 times as long as wide, inferior margin with 8 setae (all SS, on distal half), superior margin with 2 setae (both SS, distal); dactylus 3.3 times as long as proximal width, superior margin with 5 setae (all SS, distal).

Pereopod 7 basis 3.3 times as long as wide, inferior margin with 4 setae (3 SS, 1 RFS), lateral face with 1 seta (SS), superior margin with 3 setae (all SS); ischium 3.5 times as long as wide, inferior margin with 3 setae (all SS, 2 distal), lateral face with 1 seta (SS, distal), superior margin with 3 setae (2 SS, 1 PLS); merus 1.7 times as long as wide, inferior margin with 4 setae (all SS, distal), distosuperior margin with 2 setae (both SS); carpus 3.4 times as long as wide, inferior margin with 8 setae (3 PLS, 3 SS, 2 sub­marginal SS), superior margin with 5 setae (2 SS, 2 sub­marginal SS, 1 distal RFS); propodus 8.3 times as long as wide, inferior margin with 3 setae (all SS), lateral face with 1 seta (SS, proximal), superior margin with 4 setae (all distal, 3 SS, 1 PLS); dactylus 6.0 times as long as proximal width, superior margin with 5 setae (all SS), inferior margin with 1 seta (SS).

Pleon lateral sides indent and posterior end coming to a rounded point, with scattered simple setae. Operculum 2.7 times as long as proximal width, medial keel with robust setae and lateral and distal margin with numerous long setae (unable to identify actual type of setae).

Male: Similar to female in setation and spines although spines are more pronounced. Larger than female. Cephalon posterolateral margin squarer than in female, reaching beyond anterolateral margin of pereonite 1. Ventrally, frons not as narrow as in female (female not illustrated in lateral view), mouthparts not complete, so unable to comment on their position. Pereonite 4 anterolateral margin and pereonite 5 posterolateral margin with pair of robust setae; pereonites 1–5 anterior margins higher than in female; pereonites 5–7 not as rounded as in female. Pleon 1.1 times as long as proximal width.

Remarks: Notopais spicata is distinguished by the prominent spines on the anterior margins of the first 5 pereonites and the single spine on each of the first three articles of antenna 2. This species was previously considered to be a junior synonym of N. quadrispinosa by Hessler & Thistle (1975) and Brandt (1990). After redescribing the type material for both species, it is clear that they are distinct. The spines on the cephalon and anterior margins of the first five pereonites of N. spicata are more strongly produced and more acute than those of N. quadrispinosa ; the anterior spines on the fourth pereonite are set back from the anterior margin of N. quadrispinosa while in N. spicata these spines are on the absolute anterior margin; and the shape of pereonites 5–7 differs markedly between the two species, in N. spicata the lateral margins are rounded and in N. quadrispinosa , the anterolateral margins are pointed towards the cephalon. The arrangement of spines and robust setae on both antennae is another character that one can use to distinguish the two species. Robust setae feature much more prevalently on the antennal article margins of N. quadrispinosa .

Schultz (1976) redescribed N. spicata from material collected from Antarctica. Schultz also assessed the illustration and description by Vanhöffen (1914) and created a new species Pseudarachna vanhoeffeni (incorrectly labelled new combination). This species was based on Vanhöffen’s description, which stated that it only has one uropodal ramus. Examination of Vanhöffen’s specimen revealed that the uropod is biramous, the exopod is minute, and may quite easily be overlooked. The name is considered to be a junior synonym of N. spicata .

Distribution: Antarctica, eastwards from the Prince Olav coast to the Anvers Islands, including the areas of the Davis and Ross Seas, from 36.6–560 metres.

Figures

FIGURE 1. Notopais spicata Hodgson, 1910. A, D – I, female holotype, 3.0 mm; B, C, Vanhöffen’s specimen, male, 3 mm. A, dorsal view; B, lateral view; C, dorsal view; D, left antenna 1; E, right antenna 2; F, right pereopod 1; G, left pereopod 7; H, operculum; I, operculum, lateral view.