Cladocarpus formosus Allman, 1874

Altuna, Álvaro, Murillo, Francisco J. & Calder, Dale R., 2013, Aglaopheniid hydroids (Cnidaria: Hydrozoa: Aglaopheniidae) from bathyal waters of the Flemish Cap, Flemish Pass, and Grand Banks of Newfoundland (NW Atlantic), Zootaxa 3737 (5), pp. 501-537 : 511-515

Cladocarpus formosus Allman, 1874

( Figs. 1 C, 4A–H, tables 1, 5, 9, 11–12)

Cladocarpus formosus Allman, 1874: 478 , pl. 68, fig. 1, 1a–b.—Kirchenpauer 1876: 26.—Allman 1877: 50.—Hartlaub 1896: 182.—Schneider 1898: 542.—Nutting 1900: 110.—Jäderholm 1909: 110.—Ritchie 1909: 310, fig. 1.—Billard 1910: 46.— Broch 1910: 207.—Kramp 1914: 1060.—Broch 1918: 85, fig. 45.—Jäderholm 1919: 11.—Bedot 1921: 325.—Kramp 1932a: 63.—Kramp 1932b: 20.—Kramp 1938: 39.—Kramp 1942: 21.—Kramp 1943: 44.—Vervoort 1966: 149.—Naumov 1969: 524, fig. 378.—Antsulevich 1987: 118.—Stepanjants 1989: 416.—Ramil & Vervoort 1992: 171.—Cornelius 1995: 205, fig. 48A–G.—Calder 1997b: 89.—Calder & Vervoort 1998: 54.—Ramil et al. 1998: 29.—Schuchert 2000: 413 (Table 1).— Desbruyères et al. 2001: 1334.—Schuchert 2001: 139, fig. 119A–D.—Moura et al. 2012: 720.

Cladocarpus speciosus Verrill, 1879: 311 .—Nutting 1900: 116, pl. 28, fig. 8–11.—Whiteaves 1901: 28.—Kindle & Whittaker 1917: 233.—Fraser 1918: 361.—Fraser 1921: 179, fig. 106.—Fraser 1944: 41, pl. 90, fig. 399a–d.—Fraser 1946: 413.— Vervoort 1966: 149.—Calder 1997b: 89.

Cladocarpus crenulatus Levinsen, 1893: 210 , pl. 8, fig. 13–14.—Vanhöffen 1897: 246.—Jäderholm 1909: 110.—Ritchie 1909: 314.

Cladocarpus dubius Broch, 1910: 207 .—Kramp 1943: 44.

Material examined. FN3L06 L44, one fertile colony 9.0 cm high; FN3L06 L51, one fertile colony 7.0 cm high; FN3L06 L85, one fertile colony 9.5 cm high; PLA07 L70, 2 fertile colonies, largest one 8.0 cm high; PLA07 L86, one fertile colony 31.5 cm high; PLA07 L87, 2 colonies, largest one 22.0 cm high, one fertile; PLA07 L93, one fertile colony 19.1 cm high; PLA07 L101, one colony 19.5 cm high; FC07 L21, 2 colonies, largest one 12.1 cm high, one fertile; FC07 L23, one sterile colony 6.2 cm high; FC07 L155, one fertile colony 14.5 cm high; FC07 L166, 4 colonies, largest one 9.2 cm high, one fertile; FC07 L167, 2 fertile colonies, largest one 13.0 cm high; FC07 L171, one fertile colony 5.5 cm high; FN3L08 L66, one fertile colony 22.5 cm high; FN3L08 L88, 3 colonies, largest one 19.0 cm high, 2 fertile; FN3L09 L88, 3 colonies, largest one 44.0 cm high, one fertile; FN3L10 L35, one sterile colony 9.5 cm high; NEREIDA0509 RD4, 5 fertile colonies, largest one 8.3 cm high; NEREIDA0509 RD6, 5 colonies, largest one 10.1 cm high, 4 fertile; NEREIDA0509 RD10, 15 colonies, up to 11.0 cm high, some fertile; NEREIDA0509 RD12, 8 colonies, up to 11.5 cm high, some fertile; NEREIDA0509 RD15, 14 colonies, up to 11.7 cm high, some fertile; NEREIDA0509 RD18, 14 colonies, up to 10.8 cm high, some fertile; NEREIDA0509 RD19, 18 colonies, up to 12.8 cm high, some fertile; NEREIDA0509 RD20, 22 colonies, up to 12.7 cm high, some fertile; NEREIDA0509 RD21, 2 fertile colonies, largest one 8.5 cm high; NEREIDA0509 RD22, 20 colonies, up to 9.0 cm high, some fertile; NEREIDA0509 RD23, 21 colonies, up to 9.5 cm high, some fertile; NEREIDA0509 RD24, 34 colonies, up to 11.5 cm high, some fertile; NEREIDA0609 RD27, 5 colonies, largest one 11.0 cm high, some fertile; NEREIDA0609 RD28, 2 colonies, largest one 7.3 cm high, one fertile; NEREIDA0609 RD41, 6 colonies, up to 7.6 cm, some fertile; NEREIDA0709 RD49, 3 fertile colonies, largest one 8.8 cm high; NEREIDA0709 RD51, one fertile colony 14.3 cm high; NEREIDA0709 RD57, 2 fertile colonies, largest one 17.5 cm high; NEREIDA0709 RD59, 6 fertile colonies, largest one 14.2 cm high; NEREIDA0610 RD62, 20 colonies, up to 5.7 cm high, some fertile; NEREIDA0610 RD63, 12 colonies, up to 8.0 cm high, some fertile; NEREIDA0610 RD64, 9 colonies, up to 5.3 cm high, some fertile; NEREIDA0610 RD65, 51 colonies, up to 9.8 cm high, some fertile; NEREIDA0610 RD66, 50 colonies, up to 11.0 cm high, some fertile; NEREIDA0610 RD67, 5 fertile colonies, largest one 7.0 cm high; NEREIDA0610 RD71, 6 colonies, up to 6.0 cm high, some fertile; NEREIDA0610 RD74, 42 colonies, up to 17.0 cm high, some fertile; NEREIDA0710 RD76, 36 colonies, up to 13.5 cm high, some fertile; NEREIDA0710 RD77, 8 colonies, up to 12.5 cm high, some fertile; NEREIDA0710 RD78, one sterile fragment 2.7 cm high; NEREIDA0710 RD79, 2 fertile colonies, largest one 11.0 cm high; NEREIDA0710 RD80, 18 colonies, up to 14.2 cm high, some fertile; NEREIDA0710 RD83, 2 fertile colonies, largest one 6.0 cm high; NEREIDA0710 RD85, 9 colonies, up to 10.0 cm high, some fertile; NEREIDA0710 RD86, 9 colonies, up to 18.2 cm high, some fertile; NEREIDA0710 RD87, 26 colonies, up to 17.3 cm high; NEREIDA0710 RD88, 41 colonies, up to 17.5 cm high, some fertile; NEREIDA0710 RD92, 39 colonies, up to 20.5 cm high; NEREIDA0710 RD95, 13 colonies, up to 42.0 cm high, some fertile; NEREIDA0810 RD97, 16 colonies, up to 16.5 cm high, some fertile; NEREIDA0810 RD98, 7 colonies, up to 15.6 cm high, some fertile; NEREIDA0810 RD99, 14 colonies, up to 10.5 cm high, some fertile; NEREIDA0810 RD100, 30 colonies, up to 23.2 cm high, some fertile; NEREIDA0810 RD101, 10 colonies, up to 11.4 cm high, some fertile; NEREIDA0810 RD102, 2 colonies, largest one 8.8 cm high, one fertile; NEREIDA0810 RD103, 13 colonies, up to 27.5 cm high, some fertile; NEREIDA0810 RD104, 16 colonies, up to 53.5 cm high, some fertile.

Description. Colonies light brown to whitish in alcohol, plumose, occasionally ramified, up to 53.5 cm high, arising from root-like hydrorhizae consisting of tufts of tubules supporting the stems. Hydrorhiza sometimes also discoid (hard substrate). Stem erect, polysiphonic basally (3.0 mm wide), thinning out to monosiphonic distally. Branches long, arising at acute angles from stem, either irregularly or in subopposite pairs; sometimes second order branching present.

Main axial tube in front of stem and branches, divided into 850–1100 µm long internodes by more or less straight nodes. Accessory tubes parallel, not jointed, without hydrothecae, but with numerous nematothecae. Internodes with one apophysis close to distal end, directed alternately left and right, and with 3–4 nematothecae; 1– 2 centrally placed and two axillar.

Hydrocladia up to 2.7 cm long, closely set, given off frontally at acute angles from apophyses of main tube. They are formed by up to 33 thecate internodes separated by transverse nodes, each with 8–10 internal septa (generally 8). Internodes with one hydrotheca and three one-chambered nematothecae. Hydrothecae deep, not bulging into lumen of hydrocladium or only very slightly, almost totally adnate to internode, leaving only 1/10th free distally. Walls almost parallel, long hydrothecal axis forming an acute angle with the corresponding internode; depth/width at rim= 1.15–1.74 (n= 25). Intrathecal ridge of varied shape, length and development, thin and straight or sometimes almost circular, running from abcauline wall of hydrotheca towards internode, hardly reaching the latter. Margin wavy, with normally two outer cusps on abcauline side.

Nematothecae: one mesial proximal and two laterals. Mesial adnate to hydrotheca except on first internode, where there is a distinct gap between distal end of nematotheca and hydrothecal base, tapering distally, with slightly crenulated margin, extending for 1/2–4/5th the length of abaxial wall of hydrotheca; an oblique distal septum frequently present ( Figure 4 C, D). Lateral nematothecae mostly adnate to both internode and hydrotheca, tapering distally, tip slightly rising above hydrothecal margin; aperture adaxial, with finely crenulated margin.

Phylactocarps one per hydrocladium, 3.8 mm long, arising slightly laterally to first thecate internodes, between hydrothecal base and mesial nematotheca; antler-shaped, ramified, arching over the gonothecae, composed of a small internode followed by a dichotomously branched jointed structure. Branching normally of first order (though some additional branching may occur) and up to six branches. Nematothecae abundant, in a single adaxial row (occasionally abaxially), ending in a pair distally, all with margin finely crenulated. Gonothecae 1–2 on apophyses of main tube and up to 6 at forking of phylactocarps, obovate, distally truncated, curved, hooded, with lateral, narrowly oval aperture. Sex indeterminable.

Remarks. This species is morphologically varied, and our material comprises colonies with differences in structure of the thecate internodes that we attribute to intraspecific variability. There are two extreme morphs, although intermediate material is present as well. One of these extremes corresponds with material such as that described by Schuchert (2001). The other ( Figure 4 A) exhibits the following differences: i) the basal regions of hydrothecae bulge slightly into the lumen of the hydrocladium; ii) the terminal aperture of paired lateral nematothecae is slightly below the level of the hydrothecal margin; iii) the end of the mesial nematotheca extends for 3/5–4/5th the length of the abaxial hydrothecal wall; iv) the abaxial end of the hydrothecal ridge is curved backwards, so that it reaches back to the septum (hairpin shaped).

One of the main differences between the two morphotypes is the shape of the intrathecal septum, which can be thin and straight (FC07 L167) or with its end arching backwards so that it sometimes reaches the septum again (NEREIDA0610 RD74, PLA07 L 101, Figure 4 C). This character is highly variable. Levinsen (1893: pl. 8, fig. 13) depicted hydrothecae with a slightly curved adcauline end of the hydrothecal septum, and Naumov (1969: 526) discussed differences in structure of the intrathecal septum between Cladocarpus speciosus (now a synonym of C. formosus ) and C. formosus , indicating that this character should not be considered of taxonomic importance in distinguishing between the two species. In the illustration of C. speciosus by Nutting (1900), the septum originates at the internode (see his pl. 28), while in the material studied here it begins at the abcauline wall of the hydrotheca and seldom reaches across to the internode.

The mesial nematothecae are adnate to the hydrothecae and their ends extend for 1/2–1/3 to 3/5–4/5 the length of the abaxial wall of the hydrotheca ( Figure 4 A, B). However, in the first cormidium, the mesial nematotheca is free from the hydrotheca ( Figure 4 F). This is related to the location of the phylactocarps, which occur on this internode and arise in the gap between mesial nematotheca and hydrotheca.

Internodes vary considerably in length, and so do the hydrothecae, as well as the proportion of the internodes occupied by the hydrothecae. In some colonies (FC07 L167), the hydrothecae extend along 75–86 % of the internode, whereas in others having smaller hydrothecae, only 60–68 % of the internode length is occupied (NEREIDA0610 RD74, see Table 5 ). The ratio hydrothecal length/width is also quite varied (between 1.15–1.74), with some hydrothecae almost as long as wide, while others are more than 1.5 times longer than wide.

Gonothecae occur on both the phylactocarp and apophyses (with 1–2 per apophysis) of the main tube ( Figure 4 F). Colonies with gonothecae, but lacking phylactocarps, were observed in material from several stations, including NEREIDA0610 RD74. Such specimens were usually small in size.

Cornelius (1995) noted that colonies of this species typically reach up to 8.0 cm, with specimens of as much as 15.0 cm reported by Naumov (1969). A specimen from station NEREIDA0810 RD104 was 53.5 cm high, a colony that must be considered exceptionally large.

The development of the hydrothecal cusps varies, sometimes they being so little developed that the margin appears sinuous. Branching of the hydrocaulus is frequent at the distal end of the colony, and twin main stems arising from the same hydrorhiza sometimes occur. The shape of the phylactocarp and the position of gonothecae are identical in both types of colonies.

Fewkes (1881) provided a rudimentary account of an aglaopheniid he called Aglaophenia crenata from a fragmentary and unbranched colony dredged at 41º25’N – 65º35’W (2270 m depth) off Massachusetts. Nutting (1900) redescribed and assigned it to Cladocarpus , despite the absence of a gonosome on the type, and he considered it very close to C. speciosus . His description agrees with the material of C. formosus studied here, colonies of which vary considerably in hydrothecal shape, intrathecal septum development, and position of the mesial nematotheca, and the two may be conspecific. That possibility is supported by the depth at which C. crenatus was collected, falling within the known depth range of C. formosus .

Observed depth range: 240–1885 m, within the range already known for the species. A neritic-bathyal species according to Calder (1997b), and also abyssal ( Cladocarpus speciosus, 2602 m , continental slope east of Virginia, Fraser 1944; Calder 1997b).

Fertile material. Collected in August 2006 (240–1185 m depth), June and July 2007 (406–1381 m depth), August 2008 (1016–1198 m depth), from May to August 2009 (768–1885 m depth), and from June to August 2010 (520–1589 m depth).

Distribution. Kramp (1938) considered C. formosus to be a southern species in Iceland, perhaps following Broch (1910), who regarded it as a southern Atlantic hydroid recorded sporadically in the Arctic. According to Cornelius (1995), its distribution is circumpolar in sub-arctic to arctic waters.

Cladocarpus formosus is known from the Barents Sea, Sea of Okhotsk and the Kuriles (Naumov 1969, 80– 1400 m; Antsulevich 1992, 42– 60 m in an upwelling zone, and 130 + m out of this area), Faroe Channel (Ritchie 1909, 1030 m), Iceland (Broch 1918, ca. 83–847 m; Kramp 1938, 83 m; Schuchert 2001, 83– 1020 m), Denmark Strait (Broch 1918, ca. 1444 m; Kramp 1938, 384– 1444 m), Bredfjord in south Greenland (Kramp 1932b, 260–320 m), west coast of Greenland (Broch 1918, ca. 103–1096 m; Schuchert 2001, 187– 200 m), Davis Strait (Levinsen 1893, ca. 150 m; Broch 1918, ca. 1041 m), 63º36’N – 55º15’W, 60º16’N – 47º48’W, 60º22’N – 47º27’W (Kramp 1932a, 120–1200 m), 72°32’N – 58°05’W, 69°16’N – 58°08’W (Jäderholm 1919, ca. 212–335 m), eastern Canada (Kindle & Whittaker 1917, ca. 366 m, based on literature records), Flemish Cap, Flemish Pass and Grand Banks (present study), and Banquereau, off Sable Island (Verrill 1879, ca. 365 m; Nutting 1900; Whiteaves 1901; Fraser 1918, 1944). Not recorded further south in southeastern USA by Henry et al. (2008), but collected from Rainbow Vent Field, Mid-Atlantic Ridge (36°13’N, ca. 2400 m) (Desbruyères et al. 2001).

Figures

FIGURE 1. Distribution of the five aglaopheniid species in the study area. A) Aglaophenopsis cornuta (Verrill, 1879). B) Cladocarpus diana Broch, 1918. C) Cladocarpus formosus Allman, 1874. D) Cladocarpus integer (G. O. Sars, 1874). E) Nematocarpus ramuliferus (Allman, 1874). FC, Flemish Cap; FP, Flemish Pass; GB, Grand Banks.

FIGURE 4. Cladocarpus formosus Allman, 1874. A – C) Hydrothecae. D) Detail of a hydrocladium. E, F) Phylactocarps; note in F that, on the first cormidium, a distinct gap exists between the distal end of the mesial nematotheca and the hydrothecal base; compare it with the following internode of the hydrocladium. G) Detail of a phylactocarp showing nematothecae. H) Gonotheca in frontal view, showing hood. Scale bar: A, B, C, G = 200 µm; D, F, H = 500 µm; E = 1000 µm. A = NEREIDA 0610 RD 74; B, F – H = NEREIDA 0704 RD 59; C – E = PLA 07 L 101.

Tables

TABLE 5. Cladocarpus formosus Allman, 1874. Measurements (in µm) of colonies from different locations and sources.

	PLA07 L101	NEREIDA0610 RD74	FC07 L167	NEREIDA0610 RD74	Ritchie (1909)	Naumov (1969)
Colony
Height (mm)	198	109	85–130	105	40–75	150
Hydrocladia
Length of cormidium	739–782	648–681	730–775	822–957	840	580–790
Diameter at node	146–170	192–199	148–181	70–96	---	---
Hydrothecae
Depth	523–685	435–596	600–700	518–563	570	440–580
Diameter at rim	349–399	376–424	338–405	340–398	350	310–350
Nematothecae
Length of laterals	200–216	219–233	196–219	167–192	---	---
Diameter at level of terminal aperture	34–43	37–41	64–72	23–37	---	---
Mesial, diameter of terminal aperture	57–69	64–84	42–60	52–64	---	---
Mesial, distance from terminal aperture to hydrothecal margin	203–285	140–196	296–379	297–315	---	---
Mesial, length of free adcauline part	113–142	119–138	122–139	90–112	---	---
Gonothecae
Length	---	1301–1390	1185–1210	---	1230	1000–1300
Maximal diameter in frontal view	---	674–725	650–700	---	700	500–700