Ravania doliocauda, 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 : 117-123

publication ID	https://doi.org/ 10.3853/j.2201-4349.66.2014.1595
persistent identifier	https://treatment.plazi.org/id/03E56619-FFD4-3210-F748-7E18525E4F1F
treatment provided by	Carolina
scientific name	Ravania doliocauda
status	sp. nov.

Treatment

Ravania doliocauda sp. nov.

Figs 4–8 View Figure 4 View Figure 5 View Figure 6 View Figure 7 View Figure 8 , Plate 1E

Type material. HOLOTYPE adult male, length 0.66 mm, P81195 ; ALLOTYPE adult female, length 0.75 mm, P81196 ; PARATYPE specimens, 10 ♀♀, 6 ♂♂, P81197, deposited at AM, Sydney. Additional paratypes deposited at NHM, London. All collected from Zostera capricornia at Pulgul Creek mud flats, Urangan, Hervey Bay , Queensland (25°17' S 152°52' E), V. A. Harris, 30 Nov. 2002 .

Diagnosis. Large denticle with serrated crown at base of δ seta on segment 3 of male antennule; female genital doublesomite narrow (<1/2 cephalosome width), no indication of division into anterior and posterior lobes, narrows to a point posteriorly, border setules absent except for a few at posterior apex, caudal rami excluded from posterior arch of genital double-somite; caudal furca dolioid (barrel-shaped in outline), rami long (l/w> 2), taper posteriorly, lateral and posterior edge convex, T1 lateral (1/2 way down ramus), γ seta recessed at posterolateral corner; medial patch of setules on labrum; male P2 endopod with three terminal setae.

Biometric data. Females (N = 32): maximum length (Lmax) mean 0.75 mm, range 0.72–0.78 mm, body length (Lurs) mean 0.65 mm, range 0.62–0.69 mm; cephalosome width (W) mean 0.45 mm; rostrum width (R) 0.10 mm; genital double-somite length 0.135 mm, width 0.23 mm, arch 0.03 mm; caudal ramus length 0.13 mm, maximum width 0.06 mm (1/3 down ramus).

Ratios: Lurs / W 1.44; W/R 4.5–4.75; genital double-somite width 50% of body width, arch 22% of length; caudal ramus 20% of Lurs, ramus l/ w 2.16, terminal seta T1 located 54% down lateral edge of ramus, Hicks’ index for α 85%, for β 70%.

Males (N = 20): maximum length (Lmax) mean 0.66 mm, range 0.62–0.67 mm; cephalosome width (W) mean 0.44 mm; rostrum length 0.055 mm (ventral); caudal ramus length 0.05 mm, width 0.05 mm; antennule length fully extended 0.165 mm; spermatophore 0.22 × 0.09 mm.

Ratios: Lmax / W 1.5; caudal ramus 7.5% of Lmax, ramus l/ w 1.0; antennule 20% of Lmax, antennule segment 2 24%, segment 3+4 36%, dactylus 24% of antennule length; spermatophore 33% of body length Lmax.

Description. Adult females ( Fig. 5A View Figure 5 ; Plate 1E, p. 163): colourless or very pale yellow (but see remarks below), outline of body oval, cephalosome semicircular with prominent rostrum, dorsal pits inconspicuous, very few dorsal sensilla mostly towards edge of cephalosome. Hyaline border clear, 7 µm wide ( Fig. 5F View Figure 5 ). Labrum with central patch of very short setules ( Fig. 6J View Figure 6 ). Genital double-somite ( Fig. 5B, C View Figure 5 ) narrow, no epipleural expansion or division into anterior and posterior lobes, posterior half narrow (equals width of caudal rami), very fine filiform setules towards acutely pointed posterior, dorsal surface with transverse rows of shallow pits, no cleft, notch or scar to indicate boundary between anterior and posterior regions. Caudal arch shallow, encloses most of the anal segment, but caudal rami are excluded from arch. Female genital opening ( Fig. 5D, E View Figure 5 ). Caudal furca dolioid (barrel-shaped in outline) ( Fig. 5B View Figure 5 ). Each ramus narrows posteriorly, maximum width at level of β seta, lateral edge convex with border setules, medial edge without setules, posterior edge slightly convex, dorsal surface with pits and reticulate marking posteriorly ( Fig. 6I View Figure 6 ).Terminal seta T1 halfway down lateral edge, γ seta recessed, T4 set in from medial corner. T3 absent. Antennule with pinnate seta on segment 1. Structure and setation of mouthparts and ambulatory limbs typical of family. Basis of antenna with row of small triangular setules ( Fig. 6D View Figure 6 ), segment 2 of endopod with two lateral setae, geniculate setae with plain end segment, claw with fine comb-like edge. Mandible ( Fig. 6H View Figure 6 ), maxillule ( Fig. 6A View Figure 6 ), maxilla ( Fig. 6C View Figure 6 ) and maxilliped ( Fig. 6B View Figure 6 ). Segment 1 of P1 exopod ( Fig. 6G View Figure 6 ) with crescent of fine setules parallel to edge, no area of denticulate setules on endopod. Spinous seta on P2 endopod segment 3 more than 1/2 endopod length (0.6:1) ( Fig. 7C View Figure 7 ). Serrate spinous seta on segment 2 of P3 endopod almost as long as endopod ( Fig. 7B View Figure 7 ), large serrate spinous seta on segment 3 longer than endopod (1.4:1). P4 endopod with internal spinous seta on segment 2 and first (internal) spinous seta on segment 3 plain ( Fig. 7E View Figure 7 ). Baseoendopod of P5 with long ventral seta (1/2 length of exopod), exopod broad (l/w = 1.67), ovate with acute apex ( Fig. 6E View Figure 6 ), strong ventral falciform ridge, long border setules, one subterminal dorsal seta and two apical setae ( Fig. 6F View Figure 6 ), P5s extend back 3/4 length of caudal rami and compensate for the narrow genital double-somite by forming most of the roof to the brood chamber. Females carry 10 eggs per brood.

Adult males ( Fig. 8A View Figure 8 ; Plate 1F, p. 163). Colourless or very pale yellow. Outline of body oval, anterior of cephalosome semicircular (not truncated), rostrum keeled, oval in ventral view ( Fig. 8C View Figure 8 ). Dorsal pits, sensilla and hyaline border as for female. Caudal ramus ( Fig. 8E View Figure 8 ) quadrate, setation similar to female T1 lateral, T3 absent, T4 at medial corner. Antennule ( Fig. 7F View Figure 7 ) with pinnate seta on segment 1, δ seta on segment 3 long (equal to segment 3+4+ dactylus in length), points forward, coupling denticle on segment 3 large with serrated crown, two tooth-like denticles on segment 4 ( Fig. 8F View Figure 8 ), dactylus 2/3 length of segment 3+4, apex pointed ( Fig. 8G View Figure 8 ). Other limbs as for female except P2 ( Fig. 7D View Figure 7 ) has three terminal setae on endopod (two plumose, one serrulate spinous). P5 acutely trapezoidal, first (lateral) seta of different shape to terminal setae ( Fig. 8D View Figure 8 ), first row of ventral setules about 16, row of four or five setules at base of each terminal seta. Spermatophore relatively large (1/3 body length).

Etymology. The specific name refers to the outline of the caudal furca (L. doliolum = a small barrel or cask + cauda = tail).

Remarks. All specimens collected at low tide from seagrass on the Pulgul Creek mudflats at the Urangan collection site are heavily contaminated with silt particles plus a wide variety of attached organisms (bacteria, protozoa, moulds, unicellular algae, diatoms, filamentous algae etc.). This makes critical observation of fine structure difficult or impossible. Various methods using detergents, enzymes and ultrasonic vibration have been used with varying success to clean the animals before dissection, but such treatment often

destroys the fine structure of setae and setules. Apart from their tolerance to a muddy environment, this species can survive wide environmental temperature and salinity changes. Low water during spring tides tend to occur about midday or early afternoon at Urangan leaving the seagrass beds exposed to solar radiation for up to three hours. On 30 November 2002 at 12.30 pm when the type population sample was collected, water temperature in very shallow pools containing seagrass was recorded at 31°C, despite the fact that the weather was overcast with showers. Heavy rain occurring during the low tide period, particularly during the cyclone season, will flood the mud flats and subjects all organisms living there to lowered salinity or fresh water.

Distribution. The type series (PCk 3. 11/02) was collected from Zostera capricornia on mud flats at low water spring tide. It comprised 147 ♀♀ (91 carrying eggs), 122 ♂♂ and 26 copepodids. This species has been collected from another seagrass Cymodocea serrulata in the same area, (PCk 1. 4/97. 116 ♀♀ (67 with eggs), 108 ♂♂ and 21 copepodids), but it has not been found on two other seagrasses, Halophila ovalis and H. spinulosa , both abundant in the same area, V. A. Harris 1997, 2002. A coloured form of R. doliocauda with large red area on back ( Fig. 4E, F View Figure 4 ) was collected from sea grass (? Zostera capricornia ) growing on coral sand in shallow water inside the coral reef at Green Island, Cairns, Queensland (16°43' S 146° E) 4 ♀♀, 2 ♂♂, V. A. Harris 1973.