Pleurocodonellina microperforata Tilbrook, 2006

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 (3 - 4), pp. 141-266 : 196-203

Pleurocodonellina microperforata Tilbrook, 2006

( Figure 18)

Pleurocodonellina microperforata Tilbrook, 2006, p. 173 , pl. 37C, D.

Pleurocodonellina signata: Tilbrook et al. 2001, p. 78 . Liu et al. 2001, p. 632, pl. 59, figs 1–3.

Material examined

NSMT-Te 1108 ( MIN- 8), bleached, on SEM stub; NSMT-Te 1109 ( MIN- 40), bleached, on SEM stub; NSMT-Te 1110 ( MIN- 41), bleached, on SEM stub; NSMT-Te 1111 ( MIN- 42), bleached, on SEM stub; NSMT-Te 1112 ( SES- 12), bleached, on SEM stub; NSMT-Te 1113 ( SES- 55), bleached, on SEM stub; NSMT-Te 1114 ( SES- 56), bleached, on SEM stub; NSMT- Te 1115 ( SES- 57), bleached, on SEM stub; NSMT-Te 1116 ( SES- 58), bleached, on SEM stub; NSMT-Te 1117, two dried specimens, SES site; NSMT-Te 1118, six dried specimens, MIN site; NHMUK 2016.5.13.40-42, three dried specimens, SES site.

Measurements

AzL, 0.47–0.76 (0.585 ± 0.081); AzW, 0.25–0.39 (0.325 ± 0.043) (n = 15, 1). OrL (including sinus), 0.11–0.15 (0.128 ± 0.010); OrW, 0.11–0.15 (0.125 ± 0.009) (n = 15, 1). OvL, 0.18– 0.20 (0.186 ± 0.008); OvW, 0.19–0.22 (0.206 ± 0.009) (n = 15, 1). AvRosL, 0.07–0.09 (0.083 ± 0.006) (n = 15, 1). Largest colony observed 15 mm across.

Description

Colony irregular or roughly circular, forming a unilaminar, encrusting sheet; dried specimens light tan or tinged with light reddish brown; embryos orange. Zooids ( Figure 18 (a–c)) delineated by flanking areolae and suture line. Frontal wall dimpled, with 8–15 conspicuous areolae along each lateral margin, fewer along proximal margin. Primary orifice ( Figure 18 (d)) has anter broader than long; sinus broadly U-shaped, with nearly straight sides, or slightly drop shaped; flanked by bracket-like condyles, each having a long zone of minute denticles ( Figure 18 (e)). Marginal zooids with 0–2 tiny distal oral spines (evident as spine scars in Figure 18 (a)), soon covered. Peristomial rim sharp, low, continuous around orifice in both ovicelled and non-ovicelled zooids. Single avicularium proximolateral to orifice, directed proximally or less commonly proximolaterally or proximomedially; pivot bar complete; mandible short- or long-triangular, acute ( Figure 18 (b)) or rounded ( Figure 18 (c)) at end. Ovicell prominent, but with increased secondary calcification can become subimmersed or even endozooidal, flush with colony surface. Ooecium is bounded proximally by raised peristomial lip; dimpled secondary calcification leaves crescentic smooth central area with many tiny, irregular pseudopores in ectooecium. Zooids interconnect by numerous uniporous septula in the distolateral and distal walls ( Figure 18 (f)). Ancestrula (not shown) like autozooids, but smaller, surrounded by a distal, paired distolateral and paired proximolateral daughter zooids.

Remarks

A similar species, Pleurocodonellina signata ( Waters, 1889) , was once regarded as nearly circumtropical on shallow reefs. Tilbrook (2006) distinguished two new morphospecies similar to P. signata in the Solomon Islands, describing them as P. microperforata and P. macroperforata . We identified our material as M. microperforata on the basis of the often nearly square orificial sinus (not markedly drop shaped); the small suboral avicularium proximolateral to the orifice, usually with a triangular mandible; and small pseudopores in the ooecium. In Pleurocodonellina microporforata from the Solomon Islands ( Tilbrook 2006), zooids can have single or paired avicularia (we observed only single avicularia), and the avicularia are usually directed proximolaterally (in our specimens, they are quite often directed proximally). Both P. signata and P. macroperforata differ from P. microporforata in tending to have longer avicularia and a drop-shaped rather than a parallelsided orificial sinus, and P. macroporforata has larger pseudopores in the ooecium. In P. signata , the proximolateral-oral avicularia are enlarged in some zooids, reaching up to two-thirds the zooid length; in P. macroperforatea , the proximolateral-oral avicularia are single, invariably directed proximomedially, and sometimes replaced by a large, spatulate avicularium reaching up to two-thirds the zooid length.

One specimen from the SES site ( Figure 18 (c)) is atypical; compared to other specimens, the avicularia are more rounded distally, the pseudopores in the ooecium appear larger and the oral sinus tends to be drop-shaped. While this specimen could represent another species, it is not clear that this is the case: the avicularia are similar in size range and position to those in other colonies, and the condylar denticulation is the same. Furthermore, there is intracolony variation in other colonies in the shape of the oral sinus (sometimes it is drop shaped) and shape of the mandible (sometimes rounded).

Occurrence

This species was common at the SES and MIN sites ( Table 1). Pleurocodonellina microperforata is broadly distributed in the subtropical to tropical western Pacific, previously

known from the Solomon Islands, Vanuatu, and the East and South China Seas ( Tilbrook 2006).

Genus Smittina Norman, 1903b

Smittina nitidissima ( Hincks, 1880)

( Figure 19 (a, b))

Porella nitidissima Hincks, 1880, p. 78 , pl. 10, fig. 2.

Smittina nitidissima: Harmelin et al. 2009, p. 180 , fig. 8(a–f) (see this reference for additional synonyms).

Material examined

NSMT-Te 1119 ( MIN- 2), bleached, on SEM stub.

Measurements

AzL, 0.42–0.63 (0.55 ± 0.059); AzW, 0.26–0.41 (0.32 ± 0.044) (n = 15, 1). SecOrL, 0.11–0.15 (0.12 ± 0.011); SecOrW, 0.11–0.14 (0.12 ± 0.009) (n = 15, 1). OvL, 0.18–0.22 (0.20 ± 0.015); OvW, 0.22–0.28 (0.25 ± 0.014) (n = 15, 1). Single colony, 6 mm in diameter.

Description

Colony forming a unilaminar, encrusting sheet. Zooids ( Figure 19 (a)) delineated by groove and suture line. Frontal wall convex, weakly rugose, covered with small pseudopores; with a few small areolae along lateral and proximal margins. In older zooids, pseudopores can form a trabecular network in the thickened secondary calcification. Primary orifice immersed; D-shaped, with very broad, alate lyrula; condyles blunt, weakly developed, proximolateral to lyrular alae. Ovicelled zooids have a median suboral avicularium inside peristome; rostrum perpendicular or angled to frontal surface; spatulate, with serrate edge distally. Most zooids have one or two additional avicularia on peristomial rim lateral to orifice, similar in size and shape to median avicularium, rostrum angled to frontal plane and directed proximolaterally. Ovicell ( Figure 19 (b)) hyperstomial in young zooids, becoming subimmersed or sometimes endozooidal with age, when secondary calcification covers ooecium (except for pseudopores); ooecium is uniformly covered with around 12 circular to irregular pseudopores; secondary calcification forms thin, raised lip along proximal ooecial margin. Ancestrula not observed.

Remarks

Harmelin et al. (2009) provided a good description of this species based on Lebanese material and reviewed various previous records worldwide. Zooids in our specimen have a broader lyrula than in the Lebanese material, but other characters match well.

Occurrence

We found a single colony at the MIN site. This species was originally described from Madeira ( Hincks 1880). Harmelin et al. (2009) considered there to be valid records from Brazil, the Mediterranean, West Africa and the Red Sea, and suggested that the small colony size and typically abundant ovicells might facilitate dispersal on ships. These authors also noted, however, the alternative possibility that scattered, geographically disjunct populations might constitute a species complex distributed globally in warm waters.

Genus Smittoidea Osburn, 1952

Smittoidea pacifica Soule and Soule, 1973

( Figure 19 (c, d))

Smittoidea pacifica Soule and Soule, 1973, p. 380 , fig. 1(e–h).

Smittoidea pacifica: Ryland and Hayward 1992, p. 268 , fig. 24(e, f). Tilbrook et al. 2001, p. 78, fig. 18(e). Tilbrook 2006, p. 177, fig. 38(a, b).

Not Smittoidea pacifica: Rho and Kim 1981, p. 65 , pl. 5, figs 4 and 5. Seo 2005, p. 416, pl 142(b) and 143.

Material examined

NSMT-Te 1120 ( SES- 4), bleached, on SEM stub; NSMT-Te 1121, dried specimen, SES site; NSMT-TE 1122 ( SES- 53), bleached, on SEM stub.

Measurements

AzL, 0.48–0.67 (0.549 ± 0.057); AzW, 0.28–0.45 (0.344 ± 0.046) (n = 15, 1). SecOrL (including sinus), 0.14–0.19 (0.152 ± 0.013); SecOrW, 0.12–0.15 (0.130 ± 0.008) (n = 15, 1). AvRosL, 0.09–0.16 (0.136 ± 0.024); AvRosW, 0.04–0.06 (0.052 ± 0.006) (n = 15, 1). OvL,

0.13–0.17 (0.152 ± 0.012); OvW, 0.20–0.25 (0.225 ± 0.020) (n = 8, 1). Largest colony observed 10 mm across.

Description

Colony irregularly circular, forming an encrusting, unilaminar sheet; off- white, with glistening ectocyst. Zooids ( Figure 19 (c)) delineated by line of calcification flanked by columns of areolae. Frontal wall convex, tuberculate; each lateral margin with up to 12 small, circular areolar openings. Primary orifice deeply immersed, broader than long, with broad, moderately high, alate lyrula occupying most of proximal margin. Condyles small, rounded on each side at level of top of lyrula; close to alae, delineating a roughly circular sinus on each side. Peristome raised, complete; secondary orifice with deep proximal pseudosinus. Pair of tiny pseudopores proximolateral to peristomial sinus, probably associated with avicularian chamber. Single median avicularium proximal to orifice; rostrum slightly raised from frontal surface, directed proximally; mandible longtriangular, acute; crossbar complete. Ovicell ( Figure 19 (c, d)) endozooidal. Ooecium broader than long; transverse central area of ectooecium free of secondary calcification and covered with minute pseudopores. Peristome extends continuously across proximal part of ooecium. Oral spines lacking. Ancestrula not observed.

Remarks

Our material matches well the original description of this species from Oahu, Hawaiian archipelago ( Soule and Soule 1973), and except for having slightly larger zooid size, is virtually indistinguishable from material from the Great Barrier Reef ( Ryland and Hayward 1992). Material from the Solomon Islands ( Tilbrook et al. 2001) is similar in most characters, except that zooids have much larger areolar openings relative to zooid size. Korean material reported as S. pacifica ( Rho and Kim 1981; Seo 2005) appears to be another species; compared to S. pacifica , zooids have a much larger median avicularium with a wider, non-acute mandible; the areolae are proportionally much larger; and the pseudopores in the ooecium are much larger.

Occurrence

We found five colonies at the SES site . Soule and Soule (1973) noted that at least some of the material they examined from the Galapagos Islands appeared identical to Hawaiian material, but observed six oral spines on a zooid in one specimen, indicating a species other than Smittoidea pacifica . Ryland and Hayward (1992) expressed doubt whether S. pacifica occurs at all in the Galapagos or, by extension, in the eastern Pacific . We consider S. pacifica to be distributed in the subtropical to tropical, central to western Pacific , with records from Hawaii, Vanuatu, the Solomon Islands and Okinawa.

Family LANCEOPORIDAE Harmer, 1957

Genus Calyptotheca Harmer, 1957

Calyptotheca reniformis Tilbrook, 2006

( Figure 20 (a))

Calyptotheca reniformis Tilbrook, 2006, p. 228 , pl. 50A–C. Material examined

NSMT-Te 1125 (SES-5), bleached, on SEM stub; NSMT-Te 1126, two dried specimens, SES site; NSMT-Te 1127 (REEF-2), bleached, on SEM stub; NSMT-Te 1101, dried specimen, SES site (with Parasmittina serrula ); NHMUK 2016.5.13.72, dried specimen, SES site (with Torquatella duolamellata ).

Measurements

AzL, 0.39–0.58 (0.473 ± 0.042); AzW, 0.27–0.39 (0.330 ± 0.029) (n = 20, 1). AzOrL, 0.089 –0.110 (0.099 ± 0.007); AzOrW, 0.083 –0.114 (0.106 ± 0.009) (n = 12, 1). OvZOrL (secondary), 0.096 – 0.114 (0.103 ± 0.006); OvZOrW, 0.12–0.13 (0.123 ± 0.005) (n = 7, 1). OvL, 0.24–0.35 (0.303 ± 0.037); OvW, 0.26–0.35 (0.309 ± 0.033) (n = 7, 1). Largest colony observed 11 × 5 mm.

Description

Colony forming a unilaminar, encrusting sheet; off- white, slightly tinged with orange. Zooids ( Figure 20 (a)) distinct, separated by raised suture line. Frontal wall flat to weakly convex, completely covered with low tubercles, among which are tiny pseudopores having narrow, reniform opening; five to nine slit-like areolar openings along each lateral margin. Orifice of non-ovicelled zooids pear-shaped, with U-shaped sinus separated from anter by conspicuous condyles; condyles denticulate at end. Secondary orifice of ovicelled zooids wider than primary orifice of non-ovicelled zooids, with shallower, broader sinus. Single small adventitious avicularium in midline proximal to orifice; rostrum oval, raised, mandible directed proximally, crossbar complete; rostrum separate from orifice by about one rostral length. Ovicell ( Figure 20 (a)) large; subimmersed or endozooidal; ooecium covered with tubercles and tiny reniform pseudopores. Spines lacking. Ancestrula not observed.

Remarks

This species is easily recognisable by its distinctive reniform pores. Our material well matches Tilbrook’ s (2006) original description and illustrations; differences from the holotype specimen include a more conspicuously tuberculate, rugose frontal wall and ooecium; a somewhat deeper oral sinus on ovicelled zooids; and ovicells that are not as deeply embedded.

Occurrence

We found seven colonies, at the SES and REEF sites. This species was previously known only from the Solomon Islands ( Tilbrook 2006).