Halecium petrosum Stechow, 1919

Schuchert, Peter, 2005, Taxonomic revision and systematic notes on some Halecium species (Cnidaria, Hydrozoa), Journal of Natural History 39 (8), pp. 607-639 : 621-622

Halecium petrosum Stechow, 1919

( Figure 8 )

Halecium robustum: Motz-Kossowska 1911, p 346 , Figure 14 ; Neppi 1921, p 13, Figures 4 , 5 .

[Not Halecium robustum Pieper 1884, p 166 .]

Halecium petrosum Stechow 1919, p 36 , new name; Coma et al. 1992, p 162, Figure 1A ; Peña Cantero and García Carrascosa 2002, p 69, Figure 14 a–c.

Material examined

MHNG INVE 26665 , Anse de Troc , Banyuls-sur-Mer Pyrénées Orientales, France, 2 m, coll. P. Schuchert, 23 June 1997, fertile female . MHNG INVE 29763 , Spain, Mallorca , Cala Murada, coll. P. Schuchert, 23 August 2000, 0.5 m, on rock and red algae, shows signs of multiple re-growth and regenerations, identification not entirely secure .

Description

Colonies erect, branched, shoots 5–15 mm, monosiphonic, composed of main axis and shorter side-branches. Erect parts segmented by alternately oblique nodes; nodes distinct, internodes about 0.5–0.6 mm long, diameter 80–90 mm. Perisarc smooth. Side-branches originate from hydrophores. Hydrotheca near segment end, on very short hydrophore; hydrotheca does not reach beyond level of node. Primary hydrotheca with straight or slightly curved walls, basal diameter 0.10–0.12 mm, depth 20–30 mm, desmocytes present. Hydrophore without pseudodiaphragm. Secondary hydrotheca on corrugated hydrophore of variable length, several times longer than primary hydrophore. Gonothecae on main stem. Female gonotheca 0.6–0.7 mm long and about 0.5 mm broad, main body ovoid, bilaterally symmetric through a lateral hydrotheca that overtops gonotheca body, with crease-line running from hydrotheca along gonotheca body. Male gonothecae without hydrotheca, club-shaped, slightly curved or not, length 0.5–0.55 mm.

Additional information

Stems may reach 3 cm in height. Female gonotheca with two hydranths ( Motz-Kossowska 1911).

Biology

Depth range 1–200 m, grows on a variety of solid substrata. Fertile colonies observed from June to October ( Peña Cantero and García Carrascosa 2002). Ecological aspects were investigated by Coma et al. (1992).

Distribution

Mediterranean. Type localities: Cap Béar and Cap Abeille near Banyuls-sur-Mer, France, Mediterranean .

Remarks

Motz-Kossowska (1911) identified abundant material from Banyuls as Halecium robustum Pieper, 1884 . The latter name was recognized by Bedot (1912, p 14) as a synonym of H. lankesterii (see also Hamond 1957 for more invalid homonyms of Halecium robustum ). Because Motz-Kossowska’s material had female gonothecae that differed from typical H. lankesterii, Stechow (1919) attributed it to a new species with the name Halecium petrosum (compare Figures 8F and 7E ). Also the trophosomes of Halecium lankesterii and H. petrosum are quite distinct (compare Figures 7B and 8B , and remarks under H. lankesterii ).

Figures

Figure 1. Halecium scutum Clark, 1877; colony silhouettes of material from The Faroes. (A) MHNG INVE 33550; (B) BIOFAR station 699; (C) BIOFAR station 459. Scale bar: 2 cm.

Figure 4. Halecium halecinum (Linnaeus, 1758). (A–C) Segments of monosiphonic parts, with secondary hydrothecae, note length variation of internodes, BIOFAR station 350, 205 and 351; (D) BIOFAR 351, female gonotheca in side view; (E) as in (D), but seen from anterior side, note bipartite hydrotheca; (F) BIOFAR 597, male gonotheca. Scale bar: 0.2 mm.

Figure 5. Halecium beanii (Johnston, 1838). (A, D) From Roscoff; (B, C, E–H) from The Faroes. (A–C) Colony silhouettes (scale bar: 1 cm); (D–F) subterminal portions of branches (scale bar: 0.2 mm); (G) female gonotheca, middle one seen from side of hydrothecae, right one shown with developing embryos (scale bar: 0.2 mm); (H) male gonotheca (same scale bar as G).

Figure 7. Halecium lankesterii (Bourne, 1890); after material from Brittany. (A) Colony silhouette (scale bar: 5 mm); (B) part of stem (scale bar: 0.2 mm); (C) lower part of stem with characteristic ahydrothecate segments with constriction in middle (scale bar: 0.1 mm); (D) hydrothecate segment (same scale bar as C); (E) female gonotheca in oblique view, shown without hydranths (scale bar: 0.2 mm); (F) female gonotheca seen from anterior side (same scale bar as E); (G) lateral view of female gonotheca, higher magnification of opening (scale bar: 0.1 mm).

Figure 8. Halecium petrosum Stechow, 1919; after material from Banyuls-sur-Mer. (A) Colony silhouette (scale bar: 5 mm); (B) two internodes (scale bar 0.2 mm); (C) branching point (same scale bar as B); (D) hydrophore, primary and secondary hydrothecae (scale bar: 0.1 mm); (E) hydrotheca with straight walls (same scale bar as D); (F) female gonotheca in side view (same scale bar as B); (G) hydrotheca of female gonotheca in anterior view (anterior side in F is directed towards left) (same scale bar as D); (H) part of male colony, sperm masses stippled, note that this sample shows signs of multiple re-growth and regeneration, its identity is not entirely secure (scale bar: 0.2 mm).

Figure 14. Halecium banyulense Motz-Kossowska, 1911, after MHNG INVE 34237. (A) Colony silhouette (scale bar: 1 cm); (B) internode from monosiphonic part (scale bar: 0.2 mm); (C) hydrothecae with regenerated hydrothecae of second and higher degree (scale bar: 0.1 mm); (D) female gonotheca, drawn opaque to visualize radiating depressions (same scale bar as B).