Acutiramus edenensis, Harris, 2014

Harris, Vernon A., 2014, Porcellidiidae of Australia (Harpacticoida, Copepoda). II. The Importance of the Male Antennule in Taxonomy, Records of the Australian Museum 66 (2), pp. 111-166 : 145-149

publication ID	https://doi.org/ 10.3853/j.2201-4349.66.2014.1595
persistent identifier	https://treatment.plazi.org/id/03E56619-FFF0-323A-F5BC-7D81546B4EBA
treatment provided by	Carolina
scientific name	Acutiramus edenensis
status	sp. nov.

Treatment

Acutiramus edenensis sp. nov.

Figs 23–25 View Figure 23 View Figure 24 View Figure 25

Type material. HOLOTYPE adult male, length 0.48 mm, P81201 ; ALLOTYPE adult female, length 0.68 mm, P81202 ; PARATYPE material, 5 ♀♀, 3 ♂♂, 1 ♂ coupled to juvenile + 2 juveniles, P81203, deposited at AM, Sydney. Additional paratypes deposited at NHM, London. All collected from Ecklonia radiata at Arrawarra Headland, Woolgoolga, northern NSW (30°03' S 153°02' E), V. A. Harris, 1982 .

Diagnosis. No plumose setae on segment 2 of male antennule, anterior lobe with δ on segment 3 long, fingerlike, ventral blade absent, coupling denticles on segment 4 with serrated edge ( Fig. 25G View Figure 25 ), dactylus broad with terminal claw-like hook and large lateral indentation ( Fig. 25B, C View Figure 25 ); P3 endopod with internal seta on segment 1; rostrum prominent, without “lens”, no median anterior bulge to cephalosome; male shoulders rounded, no epaulette; lateral edge of female caudal ramus slightly convex, posterior half of medial edge with setules, terminal setae plain, T1 as large as T4, T2 and T3 close together, not parallel to posterior edge, space between T3 and T4 about 1/3 length of oblique posterior edge, α and β not close (1/3 length of ramus apart); female P5 exopod truncated lanceolate; male spermatophore very small (<15% of body length).

Biometric data. Females (N = 20): maximum length (Lmax) mean 0.67 mm, range 0.63–0.72 mm, body length (Lurs) mean 0.64 mm, range 0.59–0.69 mm; cephalosome 0.42 mm, range 0.40–0.44 mm; rostrum width 0.115 mm; genital double-somite width 0.23 mm, length 0.16 mm, height of arch 0.09 mm; caudal ramus length 0.78 mm, width 0.28 mm.

Ratios: Lurs / W 1.52; W/ R 3.5 ; genital double-somite w/l 1.47, arch 56% of somite length; caudal ramus 12% of body length (Lurs), caudal ramus l/ w 2.8, Hicks index for β 53 %.

Males (N = 15): maximum length (Lmax) mean 0.49 mm, range 0.45–0.51 mm, body length (Lurs) mean 0.47 mm, range 0.44–0.49 mm; cephalosome width 0.35 mm; caudal ramus length 0.02 mm, width 0.018 mm; antennule fully extended 0.15 mm; spermatophore 0.06 mm × 0.018 mm.

Ratios: Lurs / W 1.35; caudal ramus l/ w 1.1; antennule 32% of body length (Lurs), antennule segment 2 23%, segment 3+4 40%, dactylus 33% of antennule length; spermatophore 12% of body length (Lurs).

Description. Adult females ( Fig. 23A View Figure 23 ): colourless, anterior outline of cephalosome semicircular, rostrum prominent, no median bulge above rostrum, no lens-like structure in rostrum. Dorsal pits small 2–3 µm, hyaline border granulated, 8–10 µm wide ( Fig. 25E View Figure 25 ). Very few dorsal sensilla. Genital double-somite ( Fig. 23F View Figure 23 ) almost semicircular in outline without anterolateral ridge, notch and short cleft mark boundary between anterior and posterior lobes, posterior lobe about 30% of lateral edge, arch of genital double-somite deep, accommodates more than 3/4 of caudal furca. Genital opening as shown in Fig. 23E View Figure 23 . Caudal ramus ( Fig. 23B View Figure 23 ) rhomboid, length about 21/2 times width, medial edge straight with fine setules from level of β to T4, lateral edge slightly convex with border setules distally, α and β setae not close,terminal setae plain, T2 and T3 very close together, space between T3 and T4 with fine setules, 1/3 length of oblique posterior edge, T4 inserted at rounded posterior apex. No plumulose setae on antennule. Structure and setation of mouth parts and ambulatory limbs typical of family.Antenna ( Fig. 25A View Figure 25 ) with row of triangular setules on basis, five plumulose setae plus one finely serrulate spinous seta on exopod, segment 2 of endopod with three lateral setae, end part of geniculate setae plain, terminal claw comb-like, long. Mandibular palp without setules on anterior lobe. Maxillule, maxilla and maxilliped as described for A. bipunctatus . No peg area on P1 endopod. Serrulate spinous seta on segment 3 of P2 endopod shorter than endopod (0.75:1) ( Fig. 24D View Figure 24 ). P3 with internal seta on segment 1 of endopod, serrulate spinous seta on segment 2 of P3 endopod ( Fig. 24A View Figure 24 ) shorter than endopod, large serrate spinous seta on segment 3 longer than endopod (1.37:1).Endopod of P4 with internal seta on first segment, plain spinous seta on segment 2 and first (internal) seta of segment 3 ( Fig. 24E View Figure 24 ). Exopod of P5 lanceolate, truncated posteriorly, two dorsal setae, one very small and one larger sub-terminal, one apical seta, dorsal surface with pits ( Figs 23G, H View Figure 23 ). See Remarks for number of eggs carried by the female.

Adult males ( Fig. 23D View Figure 23 ) colourless. Anterior of cephalosome truncated semi-ellipse, no medial bulge above rostrum or lens-like body in rostrum, shoulders rounded. Caudal ramus ( Fig. 23C View Figure 23 ) quadrate, medial edge straight, lateral edge slightly convex, T2 and T3 very close, T4 set in from medial corner, terminal fringe of fine setules. Antennule ( Figs 25C View Figure 25 ), no plumose setae on segment 2, anterior lobe on segment 3 extended as long finger-like process bearing δ and δ' setae, no ventral process or blade on segment 3, two elongate coupling denticles with comb-like edge on segment 4 project forward parallel to anterior lobe, distal denticle small with pinnate seta, small pointed structure in “palm” of segment 4 ( Fig. 25G View Figure 25 ), dactylus almost as long as segment 3+4 with characteristic deep indentation on its posterior edge, hooked terminally ( Figs 25B, G View Figure 25 ). Endopod of P2 with two plumose setae on terminal segment ( Fig. 24B View Figure 24 ). All setae on P4 endopod plumose, not spinous ( Fig. 24C View Figure 24 ). P5 trapezoid, no setules at base of terminal setae except first or lateral seta ( Fig. 25D View Figure 25 ). Spermatophore extremely small (about 12% of body length).

Etymology. The specific name refers to Eden NSW where the species was first discovered.

Remarks. A difference in body size and number of eggs carried by the female has been noticed between animals collected from northern NSW and those found in cooler temperate waters of southern NSW ( Table 1).

Distribution. Acutiramus edenensis has a wide geographical range covering more than 7° of latitude. The type series was collected from mixed seaweeds (including Ecklonia radiata ) in the infralittoral fringe, Woolgoolga (30°03'S), Wo3. 11/82, 35 ♀♀ (19 ovigerous), 17 ♂♂ plus 4 ♂♂ coupled to juveniles, 13 juveniles. It has been found at Broulee, NSW, (35°52'S) on Caulerpa sp., and in washings from Ecklonia radiata holdfasts at Twofold Bay, Eden, NSW, (37°06'S), TB4. 12/82, 11 ♀♀, 3 ♂♂, V. A. Harris 1982.