Fraseroscyphus irregularis ( Trebilcock, 1928 ) Trebilcock, 1928

Song, Xikun, Xiao, Zefeng, Gravili, Cinzia, Ruthensteiner, Bernhard, Mackenzie, Melanie, Wang, Shaoqing, Chen, Jinjing, Yu, Nan & Wang, Jianjun, 2016, Worldwide revision of the genus Fraseroscyphus Boero and Bouillon, 1993 (Cnidaria: Hydrozoa): an integrative approach to establish new generic diagnoses, Zootaxa 4168 (1), pp. 1-37 : 20

Fraseroscyphus irregularis ( Trebilcock, 1928) comb. nov.

( Figures 3 D–E, J, 5, 7)

Sertularella irregularis Trebilcock, 1928: 11 , pl.5, figs, 1–1b.— Stranks, 1993: 17. Symplectoscyphus irregularis — Ralph, 1961a: 818, figs. 19 d–f.— Dawson, 1992: 20.— Vervoort & Watson 2003: 209, figs. 50E–G.

Type locality. St. Clair , Dunedin, New Zealand.

Type material. Seven syntypes, two ethanol samples fixed through formalin ( NMV F57939 , NMV F57940 ), two slide samples with colonies ( NMV F57894 , NMV F57941 ), and three nematocyst slides ( NMV F57939.1– F57939.3) newly prepared from NMV F57939 , creeping on coralline algae, rock pools at low tide, St. Clair , Dunedin, New Zealand, 1923. V.3, R. E. Trebilcock. Details: —NMV F57894 ( Figure 3 D), two colonies and three fragments, six male gonothecae (three originating from within the hydrothecal cavity, two growing below hydrothecae, one detached).—NMV F57941 ( Figure 3 E), slide sample, one colony, single stolon twisted in mass, diameter 2 mm, no gonothecae, two hydranths extending out of hydrothecae, nematocyst capsules clear.—NMV F57939 , comprising remnant parent lot and three nematocyst slides (NMV F57939.1–F57939.3), 22 colonies and nine fragments, 38 female gonothecae (26 originating from within the hydrothecal cavity, seven growing below hydrothecae, five detached), four clinging organs, diameter 0.09–0.13 mm, with 2–5 lobes.—NMV F57940 , a colony creeping on alga, more than five detached gonothecae, possibly female.

Lectotype designation. —Lectotype, a fragment on the slide NMV F57894 as shown by an arrow in Figure 3 D, the best preserved fertile fragment in type material, male.—Paralectotypes, the remaining fragments on the slide NMV F57894 , male; NMV F57939 (female), comprising of three newly prepared nematocyst slides (NMV F57939.1–F57939.3), NMV F57940 (possibly female), NMV F57941 .

Measurements. Full details are given in Table 6.

Description. Trophosome. Colony small ( Figure 3 D), irregular hydrorhiza creeping on coralline alga, hydrocaulus monosiphonic, origin from stolons, erect, slightly zigzag, with two to six transverse annulations at base, irregularly branched, without apophysis ( Figure 5 B), with or without branchlet, also with one to two transverse annulations at base, no axillary hydrotheca. Regular and oblique nodes on hydrocaulus and hydrocladium, each internode slightly constricted at the distal end and bearing a hydrotheca ( Figure 5 A); hydrothecae arranged spirally in three longitudinal rows forming an angle of about 60º between every two rows ( Figure 5 A); hydrotheca tubular, no wrinkles or lines on the surface, a third of the adcauline part adnate, bending outwards; margin of hydrothecal aperture with three cusps, one adcauline and two lateral abcauline, abcauline cusps slightly larger, no intrathecal teeth; operculum composed of three triangular flaps forming a pyramid; retracted hydranth with poorly developed abcauline caecum ( Figure 5 I).

Clinging organ. Directly attached to hydrocaulus or stolon, composed of two to four repeated bubbly lobes opening distally with very thin perisarc ( Figure 5 G), accompanied by annulations near node; mature lobes connecting to several processes which might develop into branchlets or stolons ( Figure 5 H).

Gonosome. Gonothecae large, three to four times the size of hydrotheca, generally origin from within the hydrothecal cavity ( Figure 5 C–D), or growing at the base of hydrotheca ( Figure 5 E–F), pedicellate, with a short distal neck which slightly expands at distal end; male gonotheca subsphaeroidal ( Figure 5 C, F), female gonotheca long and orbicular ( Figure 5 D–E).

Nematocysts. Two types, varying in length and width, capsule spindle-shaped ( Figures 3 J, 5J–K).

Distribution. Only reported from New Zealand ( Figure 7 ): St. Clair, Dunedin; Taylors Mistake, Christchurch, Woodpecker Bay ( Trebilcock 1928; Ralph 1961a; Vervoort & Watson 2003).

Remarks. In the original description of Fraseroscyphus irregularis, Trebilcock (1928) illustrated two different gonothecae (Plate 5, 1a and 1b) but did not mention their sex. After the re-examination of the type material with abundant gonothecae, the male and female can be easily identified due to the existence of large and dense sperm masses in mature male gonothecae. The sex of the original figure 1a was found to be female and 1b male, while the gonothecae in two other related illustrations ( Ralph 1961a; Vervoort & Watson 2003) should be both female.

Trebilcock (1928) noted that the abcauline caecum was rudimentally developed. This character is not clear in the type slides. However, it can still be easily and clearly observed in some hydrothecae in the ethanol sample NMV F57939 , although most tissues are decomposed ( Figure 5 I). Ralph (1961a) also observed the abcauline caecum, but Vervoort & Watson (2003) did not observe this character after they re-examined Ralph's samples. This might have been due to the poor quality of the samples, or the rudimentally developed morphology of the abcauline caecum leading to it being overlooked. Moreover, Trebilcock did not note the clinging organs in his original description, however, at least four clinging organs ( Figure 5 G–H) are present in the type material NMV F57939 .

Figures

FIGURE 3. Type samples, nematocyst and SEM scanning images. (A – C), Fraseroscyphus hozawai, A, lectotype, ZSM 20040228, paralectotype, ZSM 20041654, 20041655; (D – E) F. irregularis, (D) NMV F 57894, the arrow showing the lectotype, the others paralectotype, (E) paralectotype, NMV F 57941; (F – G) F. macrogonus, (F) NMV F 57892.1, the arrow showing the lectotype, the others paralectotype, (G) NMV F 57892.2, paralectotype. (H – I), nematocyst capsules of F. ho z aw ai, (H) from California, MBM 280124, (I) from China, MBM 280006, 280266, 280267, H 1 – H 10, I 1 – I 4, type I, H 11, I 5 – I 6, type II, I 4 and I 6 discharged. (J) F. irregularis, NMV F 57939.1, J 1 – J 3, type I, J 4 – J 5, type II; (K) F. macrogonus, NMV F 57892.1, K 1 – K 3, type I, K 4 – K 5, type II. (L – M) SEM images F. hozawai, (L) from California, lectotype, SBMNH 347307, (M) from China, MBM 280292. (N – O), fine groves on a female gonotheca (deformed) with acrocyst, from China, MBM 102663. Scale bars: A – C = 1 cm; D – G = 1 cm; H – K = 10 µm; L – M = 150 µm; N = 500 µm; O = 100 µm.

FIGURE 5. Fraseroscyphus irregularis. (A) hydrocaulus; (B) lower part of a colony; (C) male gonotheca; (D) female gonothecae origin from within cavity of a broken hydrotheca; (E) female gonotheca growing at the base of hydrotheca; (F) male gonothecae growing at the base of hydrothecae; (G) juvenile clinging organ; (H) over matured clinging organ on hydrocaulus; (I) abcauline caecum; (J – K) nematocyst capsules. Samples: A, C, lectotype, NMV F 57894; B, F, paralectotype, NMV F 57894; D – E, G – I, paralectotype, NMV F 57939; J – K, NMV F 57939.1. Scale Bars: A – F, H = 0.5 mm; G – I = 0.2 mm; J – K = 5 µm.

FIGURE 7. Worldwide distribution of Fraseroscyphus.