Porcellidiidae of Australia (Harpacticoida, Copepoda). II. The Importance of the Male Antennule in Taxonomy Author Harris, Vernon A. text Records of the Australian Museum 2014 2014-04-02 66 2 111 166 http://dx.doi.org/10.3853/j.2201-4349.66.2014.1595 journal article 10.3853/j.2201-4349.66.2014.1595 2201-4349 4684479 Ravania doliocauda sp. nov. Figs 4–8 , 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 ; 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 ). Labrum with central patch of very short setules ( Fig. 6J ). Genital double-somite ( Fig. 5B, C ) 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 ). Caudal furca dolioid (barrel-shaped in outline) ( Fig. 5B ). 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 ).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 ), segment 2 of endopod with two lateral setae, geniculate setae with plain end segment, claw with fine comb-like edge. Mandible ( Fig. 6H ), maxillule ( Fig. 6A ), maxilla ( Fig. 6C ) and maxilliped ( Fig. 6B ). Segment 1 of P1 exopod ( Fig. 6G ) 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 ). Serrate spinous seta on segment 2 of P3 endopod almost as long as endopod ( Fig. 7B ), 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 ). Baseoendopod of P5 with long ventral seta (1/2 length of exopod), exopod broad (l/w = 1.67), ovate with acute apex ( Fig. 6E ), strong ventral falciform ridge, long border setules, one subterminal dorsal seta and two apical setae ( Fig. 6F ), 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 ; 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 ). Dorsal pits, sensilla and hyaline border as for female. Caudal ramus ( Fig. 8E ) quadrate, setation similar to female T1 lateral, T3 absent, T4 at medial corner. Antennule ( Fig. 7F ) 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 ), dactylus 2/3 length of segment 3+4, apex pointed ( Fig. 8G ). Other limbs as for female except P2 ( Fig. 7D ) 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 ), 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). Figure 4. Ravania wellsi sp. nov. Male: (A) antennule coupling denticles; (B, C) anterior cephalosome (ventral, dorsal); (D) antennule (detail of dactylus). Ravania doliocauda sp. nov. coloured variety from Cairns , northern Queensland: (E) adult female; (F) adult male. Scale bar: A, D = 0.04 mm. B, C = 0.15 mm. E, F = 0.58 mm. 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 Figure 5. Ravania doliocauda sp. nov. Female: (A) adult; (B) genital double-somite and caudal rami; (C) genital double-somite (ventral); (D, E) Genital opening (superficial and deep focus); (F) cephalosome border ( hy.so. hyaline border sense organ; mg.d. marginal gland duct; mg.o. opening to marginal gland). Scale bar: A = 0.45 mm. B, C = 0.15 mm. D, E = 0.06 mm. F = 0.08 mm. 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. Figure 6. Ravania doliocauda sp. nov. Female: (A) maxillule; (B) maxilliped; (C) maxilla; (D) antenna; (E) P5 (ventral); (F) apex of P5; (G) P1; (H) mandible; (I) caudal ramus (dorsal); (J) labrum. Scale bar: A, C = 0.08 mm. B, D, H, I, J = 0.1 mm. E = 0.19 mm. G = 0.14 mm. Figure 7. Ravania doliocauda sp. nov. Male: (A) genital somite, P5 and caudal rami (ventral, dorsal); (D) P2 endopod; (F) antennule. Female: (B) P3; (C) P2; (E) P4. Scale bar: A, C, D, E = 0.14 mm. B = 0.19 mm. F = 0.1 mm. Figure 8. Ravania doliocauda sp. nov. Male: (A) adult; (B, C) anterior of cephalosome (dorsal, ventral showing rostrum); (D) P5 (ventral); (E) caudal rami; (F) antennule showing coupling denticles; (G, H) dactylus of antennule. Scale bar: A = 0.45 mm. B, C = 0.23 mm. D = 0.11 mm. E = 0.1 mm. F = 0.06 mm. G = 0.08 mm. 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 ) 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.