Filellum disaggregatum Peña Cantero, García Carrascosa and Vervoort, 1998

Marques, Antonio C., Peña, Álvaro L., Miranda, Thaís P. & Migotto, Alvaro E., 2011, Revision of the genus Filellum Hincks, 1868 (Lafoeidae, Leptothecata, Hydrozoa), Zootaxa 3129, pp. 1-28 : 12-14

Filellum disaggregatum Peña Cantero, García Carrascosa and Vervoort, 1998

( Figure 3 A–C)

Filellum disaggregatum Peña Cantero et al., 1998: 308 –311, figs. 3a–d, 4a–e; Peña Cantero and García Carrascosa 2002: 53.

Type series. Holotype— Filellum disaggregatum Peña Cantero et al., 1998 , alcohol specimen with coppiniae (University of Valencia Coel. No. 26/MED CONG 57). Paratype— Filellum disaggregatum Peña Cantero et al., 1998 , ( RMNH Coel. no. 27771, two slides no. 3558) ( Peña Cantero et al. 1998: 298).

Type locality. From the holotype and paratype, Chafarinas Islands, Mediterranean Sea, Stn. CONG 57, sunk boat, on algae, 10.5 m, August 1991, leg. University of Valencia ( Peña Cantero et al. 1998: 298, 308).

Material examined. CHAFARINAS ISLANDS: CONG 57 (“ 10.5 m depth”, 4 August 1991, “Barco hundido”), several colonies on the algae Cystoseira spinosa Sauvageau , Rhodymenia sp. and Acrosorium uncinatum (Turner) Kylin ; with coppiniae” ( Peña Cantero et al. 1998: 298, 308), holotype and paratype of Filellum disaggregatum Peña Cantero et al., 1998 (University of Valencia Coel. No. 26/ MED CONG 57, RMNH Coel. no. 27771, two slides no. 3558, respectively).

Description of holotype. Colonies stolonal, arising from a filiform and creeping hydrorhiza growing on diverse substrata; hydrorhizal tubes 0.04–0.06 mm wide, with anastomosed perisarc, forming a more or less tight mesh, depending on substratum. Hydrothecae sessile, arising with no definite pattern from hydrorhiza, more than half of their total length adnate to substratum, parallel to hydrorhizal stolon, free part emerging from substrate plane at angles wide than 45o, usually 90o. Adnate portion of hydrothecae tubular or maximally slightly flattened, 0.25–0.33 mm (0.30 ± 0.03, n=11) long, perisarc smooth; free part cylindrical, smooth, 0.12–0.25 mm (0.18 ± 0.04, n=11) long; perisarc moderately thin; hydrothecae widening distally, margin even and smooth, with up to four renovations, tenuous flaring; hydrothecal aperture circular, 0.06–0.12 mm (0.09 ±0.02, n=11) wide, perpendicular to long axis of free part of hydrotheca. Hydranths 0.06–0.13 mm high (0.09 ±0.02, n=10), 0.08–0.11 mm wide (0.10 ±0.01, n=10) at the base of tentacles, with ca. 12–16 filiform tentacles, hypostome conical. Hydranths, when retracted, lying on the adnate space of the hydrothecae.

Gonothecae arranged in coppinia, up to 3 mm wide, varying from closely to more loosely packed, their limits distinct in dorsal view. Gonothecae 0.18–0.24 mm (0.21 ±0.02, n=10) high (from substrate to aperture), with widest part adnate to substratum, distal part bent away from substratum; general form variable, from flask-shaped to pyriform, with variable diameter up to distal part, apical part with distal neck bearing circular (sometimes oval) aperture, 0.05– 0.07 mm (0.06 ±0.01, n=10) wide, rim even and flared, occasionally with up to three renovations. Protective tubes absent, defensive function made by hydrothecae around or among gonothecae. Planulae complete their development outside gonothecae, connected to them through a mucous thread; planulae diameter larger than gonothecal aperture.

Nematocysts of one category, heterotrichous microbasic mastigophores (not seen discharged), 21–23 X 4.5– 5.5 µm (22.10 ±0.88 X 5.00 ±0.33, n=10), rice-shaped, common.

Distribution. Filellum disaggregatum was recorded only for the Chafarinas Islands, Alboran Sea ( Peña Cantero et al. 1998).

Remarks. The trophosomal morphology of Filellum disaggregatum is indistinguishable from that of F. s e rpens, and both species may be differentiated only by their coppiniae. The coppinia of F. disaggregatum is unique among species of Filellum , with pyriform gonothecae, with long necks, irregularly distributed through the coppinia and lacking protective tubes ( Peña Cantero et al. 1998).

Figures

FIGURE 3. Filellum disaggregatum Peña Cantero, García Carrascosa & Vervoort, 1998. (A) General side view of some hydrothecae of the colony. (B) Detail of the hydrotheca with renovations, side view. (C) Detail of the gonothecae with apertures. Scale bar: 200 µm (A); 100 µm (B, C).