Thornelya perarmata Harmer, 1957

Dick, Matthew H. & Grischenko, Andrei V., 2016, Rocky-intertidal cheilostome bryozoans from the vicinity of the Sesoko Biological Station, west-central Okinawa, Japan, Journal of Natural History 51, pp. 141-266 : 216-221

Thornelya perarmata Harmer, 1957

( Figure 25 (b))

Thornelya perarmata Harmer, 1957, p. 1105 , pl. 73, figs 6 – 8.

Thornelya perarmata: Ryland and Hayward 1992, p. 258 , fig. 17(c, d).

Material examined

NSMT-Te 1146 ( SES- 3), bleached, on SEM stub; NHMUK 2016.5.13.59, dried specimen, SES site (with? Exechonella sp., Celleporaria triangula , Cranosina coronata ).

Measurements

AzL, 0.38 – 0.51 (0.442 ± 0.047); AzW, 0.27 – 0.34 (0.308 ± 0.025) (n = 10, 1). OrL, 0.12 – 0.13 (0.121 ± 0.006); OrW, 0.09 – 0.10 (0.096 ± 0.003) (n = 10, 1). Larger of two colonies 4 mm across.

Description

Colony forming a unilaminar, encrusting sheet. Zooids irregular in size and shape, sometimes broader than long; distinct, delineated by groove and suture line flanked by areolae. Frontal wall markedly convex, coarsely tuberculate, rugose, sparsely covered with scattered pseudopores; young, marginal zooids lack pseudopores in extensive central region proximal to orifice. Up to 13 small areolae along each lateral margin. Orifice not deeply immersed; longer than broad; broadest in centre of anter; keyhole shaped; poster broadly concave, separated from anter by conspicuous rounded condyles. Distal margin with six (63%), seven (35%) or eight (2%) stout, straight tubular spines; large, conspicuous spine scars evident even in older zooids near colony centre. Peristome lacking. Zooids bear up to four adventitious avicularia, of two types. One type (arrows, Figure 25 (b)) has raised, circular or oval chamber, with rostrum highly angled from frontal plane; crossbar complete; mandible triangular, about twice as long as broad, acute; chamber usually with one or two small pseudopores proximal to rostrum. This type can occur anywhere on frontal wall, with mandible pointing in any direction. The other type (arrowheads, Figure 25 (b)) arises from an areolar pore, usually in distolateral corner of zooid, on one or both sides; chamber negligible; rostrum slightly raised from frontal surface distally, tilted laterally towards one side, rostral axis parallel to zooidal margin; cross bar complete; mandible acute, triangular, length at least 3 times width; pointing distally or proximally. No complete ovicells observed. Ancestrula not observed.

Remarks

According to other descriptions, the ovicell is hyperstomial, with numerous pseudopores, and with or without an avicularium on the frontal surface. Our specimens are quite similar to material described from the Great Barrier Reef ( Ryland and Hayward 1992), in which zooids have six oral spines and the same two types of avicularia. Three species have been assigned to Thornelya : T. ceylonica ( Thornely 1905) ; T. perarmata Harmer, 1957 ; and T. fuscina Tilbrook et al., 2001 . Thornelya fuscina has somewhat larger zooids, more pores in the frontal wall, and fewer oral spines (2 – 4 versus 6 – 8) than T. perarmata , and differs in the form, number and position of avicularia. According to Tilbrook et al. (2001), the zooidal orifice is narrower relative to length in T. fuscina than in T. perarmata , though this is only marginally evident from our material (OrL/OrW, 1.35 and 1.26, respectively). While T. ceylonica also has six to eight oral spines as in T. perarmata , its primary orifice is putatively wider relative to length, with a shallower poster, and avicularia are more numerous ( Harmer 1957; Tilbrook et al. 2001); to date, T. ceylonica has not been examined by SEM. Hippomenella mila Scholz, 1991 , originally described from the Philippines, may also be assignable to Thornelya .

Occurrence

We found two colonies, both at the SES site. Originally described from the Weigeu Islands, western New Guinea ( Harmer 1957), this species had subsequently been reported only from the Great Barrier Reef ( Ryland and Hayward 1992).

Family GIGANTOPORIDAE Bassler, 1935

Genus Gigantopora Ridley, 1881

Gigantopora pupa ( Jullien, 1903)

( Figure 25 (c, d))

Galeopsis pupa Jullien, in Jullien and Calvet, 1903, p. 95, pl. 12, fig. 1.

Galeopsis pupa: Canu and Bassler 1929, p. 272, text-fig. 110(a – d), pl. 28, figs 1 and 2.

Gigantopora pupa: Harmer 1957, p. 880, pl. 60, figs 3 and 9. Gordon 1984, p. 79, pl. 26F. Hayward and Ryland 1995, p. 557, fig. 11(a).

Material examined

NSMT-Te 1147 ( SES- 2), bleached, on SEM stub.

Measurements

AzL, 0.95 – 1.15 (1.063 ± 0.061); AzW, 0.57 – 0.83 (0.672 ± 0.072) (n = 10, 1). OrL, 0.257; OrW, 0.249 (n = 1). OvL, 0.32 – 0.49 (0.387 ± 0.076); OvW, 0.54 – 0.62 (0.591 ± 0.034) (n = 4, 1). Fragment observed was part of a larger colony estimated to be about 1 cm in diameter.

Description

Colony forming a unilaminar, encrusting sheet. Zooids ( Figure 25 (c)) large, coarse, distinct. Frontal wall quite convex, covered with coarse, rounded tubercles interspersed with small pseudopores over entire surface proximal to peristome. Areolar openings not evident. Primary orifice ( Figure 25 (d)) subcircular, about as broad as long, with blunt condyles; curvature of anter nearly continuous with that of poster. Peristome tall; continuous, or with proximal and distal lips separated by a sulcus on each side. Large spiramen on bulbous swelling on proximal side of peristome; spiramen variable in size and shape: circular, oval, crescent shaped, dumbbell shaped or long-elliptical. Avicularia paired, one on each side of peristome on slightly raised chamber; rostrum highly angled from frontal plane, pointing proximomedially, with tip generally touching proximal peristomial lip; mandible short-triangular, acute; crossbar complete. Ovicell ( Figure 25 (c)) hyperstomial; ooecium broader than long, with highly rugose surface and numerous pseudopores, like frontal wall; peristome extends around proximal margin of ooecium. One zooid in our specimen bears a minute hollow spine ( Figure 25 (c), arrowhead) on peristomial rim, lateral to orifice. Ancestrula not observed.

Remarks

As a synonym of G. pupa (Jullien), Harmer (1957) listed Gigantopora (as Galeopsis) brevicapitata Canu and Bassler, 1929 from the Philippines, stating that he was unable to distinguish between them. According to Canu and Bassler (1929), the former differs from the latter in having a shorter ooecium and a more salient spiramen placed lower on the peristome. In any case, Canu and Bassler (1929) also reported Gigantopora pupa from the Philippines.

Occurrence

We found a single colony at the SES site. This species occurs in the western Pacific, with previous records from Torres Strait ( Harmer 1957) and the Great Barrier Reef ( Hayward and Ryland 1995), Australia; New Zealand ( Gordon 1984); and the Philippines ( Canu and Bassler 1929).

Family ECHINOVADOMIDAE Tilbrook, Hayward, and Gordon, 2001

Genus Echinovadoma Tilbrook, Hayward, and Gordon, 2001

Echinovadoma anceps Tilbrook, Hayward, and Gordon, 2001

( Figure 26 )

Echinovadoma anceps Tilbrook, Hayward, and Gordon, 2001, p. 84 , fig. 16(c – e).

Material examined

NSMT-Te 1148 ( SES- 7), bleached, on SEM stub.

Measurements

AzL, 0.36 – 0.43 (0.396 ± 0.022); AzW, 0.25 – 0.38 (0.310 ± 0.037) (n = 15, 1). OrL, 0.10 – 0.13 (0.116 ± 0.009); OrW, 0.11 – 0.13 (0.119 ± 0.005) (n = 15, 1). OvL, 0.15 – 0.20 (0.167 ± 0.012); OvW, 0.19 – 0.24 (0.205 ± 0.011) (n = 15, 1). Larger of two colonies 3.5 mm across.

Description

Colony forming a unilaminar, encrusting sheet ( Figure 26 (a)). Zooids ( Figure 26 (a, b)) small, delineated by shallow groove. Frontal wall convex, completely covered with minute pseudopores interspersed with rounded tubercles; areolae around margin slit-like, indistinct. Primary orifice about as broad as long; anter transversely oval, separated from broadly rounded poster by conspicuous sharp condyles. Proximal and lateral margins of orifice developed as broad, flared flange, often with lateral and proximomedian lobes. Oral spines lacking. Ovicell ( Figure 26 (c)) hyperstomial; ooecium consisting of two spinous lateral lobes, fused in upper distal midline, but leaving small, oval foramen distally and larger, triangular opening proximally; ooecium covered with tubercles like those on frontal wall; margins of ovicell openings with cylindrical, spine-like denticles. One colony shows a central ancestrular complex ( Figure 26 (d)), although it is not clear which of two small, central zooids is the ancestrula, nor is the budding pattern clear.

Remarks

This species is the sole representative of a presently monotypic family and genus. Our specimens well match the original description.

Occurrence

We found two small colonies at the SES site. The only other known locality is Poanangisu, Efate, Vanuatu ( Tilbrook et al. 2001).

Family ROBERTSONIDRIDAE Rosso, Scinto, and Sinagra, 2010

Genus Robertsonidra Osburn, 1952

Robertsonidra argentea ( Hincks, 1881)

( Figure 27 (a – c))

Schizoporella argentea Hincks, 1881, p. 158 , pl. 9, fig. 6(a).

Robertsonidra argentea: Ryland and Hayward 1992, p. 261 , fig. 19(b). Liu et al. 2001, p. 644, pl. 60, figs 1 – 4. Tilbrook 2006, p. 261, pl. 57E, F.

For additional synonyms, see Tilbrook (2006).

Material examined

NSMT-Te 1149 ( MIN- 16), bleached, on SEM stub; NSMT-Te 1150, dried specimen, MIN site; NSMT-Te 1151, large colony, dried, SES site; NSMT-Te 1152, 32 dried specimens, SES

site; NSMT-Te 1153, bleached, dried specimen, SES site; NHMUK 2016.5.13.90, five dried specimens, REEF site.

Measurements

AzL, 0.59 – 0.88 (0.693 ± 0.070); AzW, 0.31 – 0.48 (0.416 ± 0.059) (n = 15, 1). OrL, 0.15 – 0.19 (0.170 ± 0.009); OrW, 0.15 – 0.19 (0.174 ± 0.011) (n = 15, 1). OvL, 0.33 – 0.42 (0.377 ± 0.026); OvW, 0.32 – 0.44 (0.377 ± 0.027) (n = 13, 1). Largest colony observed at least 60 mm across.

Description

Colony forming a unilaminar, encrusting sheet, often covering extensive areas of substratum; dried specimens white to greyish in colour. Zooids ( Figure 27 (a, b)) distinct, delineated by opposing areolae and suture line. Frontal wall quite convex, without pseudopores, uniformly covered with rounded tubercles; seven to 11 areolae along each lateral margin, fewer along transverse margins. Primary orifice ( Figure 27 (a)) as wide as long, lacking condyles; proximal half broadly V-shaped, slightly asymmetrical. One or two minute distal oral spines. Peristome low, comprising raised flange on one side proximolateral to orifice and avicularian chamber on other. Single avicularium usually present proximolateral to orifice, occurring in two types: smaller type ( Figure 27 (a, c)) has rostrum raised from frontal plane, pointing distolaterally, with short-triangular mandible; larger type ( Figure 27 (b)) has rostrum lying parallel to frontal plane, long-triangular mandible pointing proximolaterally. Some zooids lack avicularium. Ovicell ( Figure 27 (c)) hyperstomial, more densely tuberculate than frontal wall, evenly and densely covered with tiny pseudopores. Ovicelled zooids have pair of tiny, widely spaced spines on orificial rim, at proximolateral corners of ooecium. Zooids interconnect by small uniporous septula. Ancestrula not observed.

Remarks

This species is distinguished by the broadly V-shaped proximal oral sinus, lack of condyles, presence of one or two tiny oral spines, peristomial flange and dimorphic avicularia.

Occurrence

Robertsonidra argentea was abundant at the SES and REEF sites ( Table 1), with only a single colony found at the MIN site. This is a broadly distributed Indo-West Pacific species. Hincks (1881, p. 158) originally reported it from ‘ Africa, on coral ’; Hayward and Ryland (1992) surmised that this probably meant East Africa. There are subsequent records from the Red Sea, Indonesia, the Philippines, the Great Barrier Reef, China and the Solomon Islands ( Tilbrook 2006).

Figures

Figure 25. (a) Thornelya fuscina Tilbrook, Hayward, and Gordon, NSMT-Te 1145: autozooids. (b) Thornelya perarmata Harmer, NSMT-Te 1146: autozooids; arrows and arrowheads indicate two types of adventitious avicularia (see the text). (c, d) Gigantopora pupa (Jullien), NSMT-Te 1147: (c) colony view, showing ovicelled and non-ovicelled autozooids (arrowhead, minute oral spine); (d) orifice. All panels are scanning electron microscopic images of bleached specimens. Scale bars: a, b = 300 µm; c = 1.0 mm; d = 200 µm.

Figure 26. Echinovadoma anceps Tilbrook, Hayward, and Gordon, NSMT-Te 1148. (a) view of colony; (b) autozooids; (c) ovicelled autozooids; (d) enlargement of centre of colony in (a), showing ancestrular complex. All panels are scanning electron microscopic images of dried, naturally dead colony. Scale bars: a = 500 µm; b, c = 200 µm; d = 250 µm.

Figure 27. (a–c) Robertsonidra argentea (Hincks), NSMT-Te 1149: (a) autozooids near colony margin; (b) autozooids, showing two types of avicularia; (c) ovicelled and non-ovicelled autozooids. (d–f) Robertsonidra porifera (Maplestone), NSMT-Te 1155: (d) autozooids near colony margin, one showing more-common large avicularium; (e) autozooids, one showing uncommon smaller avicularium; (f) ovicelled and non-ovicelled autozooids. All panels are scanning electron microscopic images of bleached specimens. Scale bars = 300 µm.