Padina australis Hauck (1887: 44)

Liao, Lawrence M., Belleza, Dominic Franco C. & Geraldino, Paul John L., 2013, Marine algae of the Sulu Sea Islands, Philippines II: annotated list of the brown seaweeds (Phaeophyceae) from the Cuyo Islands, Phytotaxa 152 (1), pp. 1-17 : 6-10

Padina australis Hauck (1887: 44)

Type:— Cape York , Australia

Remarks:—Clearly this is one of most frequently encountered species of Padina at least in the Philippines ( Modelo & Umezaki 1984, Geraldino et al. 2005), and among the earliest recorded seaweed species in the country. Blanco (1837) provided the description of this species from Manila Bay and named it Ulva umbilicalis Linnaeus (1753: 1163) which today is recognized as the basionym of Porphyra umbilicalis (Linnaeus) Kützing (1843: 383) . The whereabouts of Blanco’s materials are unknown; therefore Merrill (1905) determined Blanco’s original description to be referable to P. australis among the exsiccata distributed as ‘Species Blancoanae 994’ ( US 904677!). This species is bistratose throughout and has been confused with the closely similar Padina boergesenii Allender & Kraft (1983: 87) which is generally 3-cell thick in the midregions ( Coppejans et al. 2009). Calcification in P. australis is very light especially on its revolute (ventral) side. The identification of our samples is chiefly based on the uniformly bistratose thallus construction observed therein. Coppejans et al. (2010) used the presence or absence of basal Vaughaniella stage (rustcolored fibrous hairs referred to by Geraldino et al. 2005) to discriminate species, however this feature needs further evaluation. Materials of P. australis studied did not show such basal juvenile stages.

Materials examined:— 78EM-12 (142 to 151), 78EM-19 (114, 115), GTV5974 Cuyo, 12 May 1964, deposited at UP Marine Science Institute ( T 11651), MSD16534 north of Cuyo , 30 April 1958, leg. E. G. Meñez, deposited at B. P. Bishop Museum .

* Padina sanctae-crucis Børgesen (1914: 45)

Type:— St. Croix , Virgin Islands .

Remarks:—This is a medium-sized plant growing to about 6 cm tall. In the field, the heavily calcified involute (dorsal) surface is distinctly discernible from the less calcified revolute surface. The Cuyo materials were originally identified as Padina japonica Yamada (1931: 69) , a species also widely distributed throughout the Philippines ( Modelo & Umezaki 1984). The conspecificity of P. japonica and P. sanctae-crucis has been suggested by some authors ( Gaillard 1975, Geraldino et al. 2005, Lewmanomont et al. 2007). Using morphological and molecular data obtained from southern Japanese and Hawaiian specimens, Ni-Ni-Win et al. (2010) upheld the distinction of the two species although both were shown to form a sister clade based on rbc L and cox 3 gene sequence comparisons. Huisman et al. (2007) found much smaller plants in shallow water Hawaiian habitats compared to those from greater depths suggesting plasticity most likely influenced by different light levels and wave action.

Materials examined:—78EM-20 (36), 78EM-21 (3 to 9).

* Padina minor Yamada (1925: 251)

Type:— Garanbi , Cape O’luan, Taiwan .

Remarks:—The specific epithet for this species has provided a convenient reason to categorize diminutive materials of Padina easily into this particular taxon, resulting in numerous misidentifications ( Geraldino et al. 2005). Many of these small species may represent juvenile stages lacking useful diagnostic features and which favor erroneous identifications. For example, Modelo & Umezaki (1984) emphasized the small thallus size of P. minor as a diagnostic feature in their taxonomic key. Tsutsui et al. (2005) noted its close resemblance to Padina australis with obvious differences only in the smaller size and more narrowly spaced concentric lines in P. minor . The materials on hand are quite small and have abundant fibrous outgrowths at the base which compared well with the extensive Vaughaniella stage seen in Thai materials ( Coppejans et al. 2010). Although the smaller sizes of mature plants are useful for species identification, it is still imperative to confirm its identity using well-established criteria such as heavy calcification on the involute surface while none on the revolute surface, bistratose thalli and non-indusiate sporangia. The identification of this species was solely based on the calcification pattern on both surfaces and on the bistratose construction observed. Unfortunately, our materials are sterile.

Materials examined:—78EM-20 (27 to 35).

Order Sphacelariales

Family Sphacelariaceae

* Sphacelaria rigidula Kützing (1843: 292)

Type:—Nuweiba, Sinai, Red Sea.

Remarks:—The materials studied were growing densely on the larger brown alga, Turbinaria ornata ( Turner 1807: 50) J. Agardh (1848: 266) , specifically on the narrow surfaces between the margins and intramarginal crown of the foliar parts. The two long, slender arms issued from mature propagula are distinctive, although at times three arms have been encountered very rarely. The presence of three arms (with occasional occurrence of two arms in one propagule) is also a feature observed in Sphacelaria carolinensis Trono (1972: 55) . Kraft (2009) hinted on the conspecificity of the two species although their distinctness has been maintained for materials from southern China ( Tseng & Lu 1983). This species is probably quite widespread in the Philippines and in other tropical regions where it was formerly known as Sphacelaria furcigera Kützing (1855: 27) , which has since been synonymized under the currently accepted name. Dawes & Mathieson (2008) listed Karak Island in Iran as the type locality of this species, but this is in fact the type locality of S. furcigera .

Material examined:—78EM-18 (422).

Order Fucales

Family Sargassaceae

* Sargassum ilicifolium (Turner) C. Agardh (1820: 11)

Basionym: Fucus ilicifolius Turner (1807: 113)

Type:— Sunda Strait , Indonesia .

Remarks:—This species is distinctive among Sargassum species partly because of its duplicated leaf margins. However, there is some confusion among the few species of Sargassum with such duplicated leaf margins. In the materials studied, ‘duplication’ was seen throughout the length of the leaf margin except for the proximal third approaching the leaf base. The ‘duplication’ was in the form of a thickened margin or a folded surface about 10 mm wide running parallel to the leaf margin. The latter was oriented in a perpendicular or more commonly, in an oblique position in relation to the lamina. The duplicated margin running along the leaf edge and slowly diminishing in width towards the leaf base resembled a horseshoe shape. The duplicated margin showed coarse dentition oriented in many directions most of the time. The sample 78EM-14 (21) bore finer teeth orderly arranged, which appeared like ordinary marginal serrations. Another variation seen in the specimen 78EM-43 (183) was an obliquely oriented thickened margin with almost no teeth. When present, teeth in this sample were very few, short and blunt. The variations seen above may be due to age differences and falling within the morphological ranges described for S. cristaefolium C. Agardh (1820: 13) .

Trono (1997) illustrated S. cristaefolium as having leaf duplications restricted to the apical sections and often resembling a small cup. The ‘duplication’ may be more accurately described as small bilabiate opposing folds which formed a shallow cup approaching a turbinate form. A species showing a similar apical morphology is S. feldmannii Ho (1967: 297) which was synonymized by Ajisaka et al. (1997) under S. crassifolium J. Agardh on the grounds of similar androgynous receptacles and phyllocysts when it should have been subsumed under S. cristaefolium based on leaf morphology. Another taxon with such cup-shaped leaf tips is S. ilicifolium var. conduplicatum Grunow ex Reinbold in Weber-van Bosse (1913: 160), commonly reported from East Asia, which has been suggested by Womersley & Bailey (1970) as possibly synonymous with S. cristaefolium . Sargassum duplicatum Bory de Saint-Vincent (1828: 127) , with its characteristic duplicated margin, has been widely recognized as similar to S. cristaefolium , but showed a significantly divergent molecular profile with S. crassifolium based on ITS sequence ( Yoshida et al. 2004). Interestingly, S. duplicatum has been listed as a synonym of S. sandei Reinbold ex Weber-van Bosse (1913: 158) by Yoshida & Yoshinaga (2010), a species that shows a less prominent cup-like apical portion. Sargassum sandei has been proposed as a synonym of S. ilicifolium by Tsuda (1988) and subsequently affirmed by Mattio et al. (2010) on the basis of DNA data. Based on molecular information and a thorough morphological examination of types and diagnoses, Mattio et al. (2010) determined several species to be representative of the morphological range shown by S. ilicifolium throughout the Indo-Pacific, such as S. sandei , S. cristaefolium , S. duplicatum , S. berberifolium J. Agardh (1848: 337) , S. droserifolium Bory de Saint-Vincent (1828: 129) , and S. turbinatifolium Tseng & Lu (1979: 9) . The synonymy proposed above is followed in the present study.

Materials examined:—78EM-14 (16 to 18, 21), 78EM-20 (87, 88), 78EM-43 (180, 181, 183, 184).

* Sargassum aquifolium (Turner) C. Agardh (1820: 12)

Basionym: Fucus aquifolius Turner (1807: 111)

Type:— Sunda Strait , off Java in Indonesia .

Remarks:—A closely similar species, S. binderi Sonder ex J. Agardh (1848: 328) has been placed in synonymy with S. oligocystum Montagne (1845: 67) by Womersley & Bailey (1970) who, after examining the type material remarked that “it is almost certainly the same as the comparatively well known S. binderi . ” The synonymy has since then been followed by later workers (e.g., Ang et al. 2008, Kraft 2009, Lee et al. 2009).

In this study, the close morphological similarity between both species made distinction difficult. One seemingly consistent feature used by many workers is the nature of the air vesicles. Trono (1997) characterized the vesicle stalk of S. oligocystum as shorter than the vesicle and slightly flattened, while in S. binderi it is mainly compressed and up to three times the length of the vesicle. Wong et al. (2008) further characterized the long stalks in S. binderi as “long leafy pedicels” in contrast to those of S. oligocystum which are terete and subtending vesicles without wings. Tsutsui et al. (2005) illustrated stalks in S. oligocystum which are about the same length as the subtended vesicles, while Coppejans et al. (2010) found flattened stalks which are usually longer than the vesicles. In the materials under study, the stalks were somewhat compressed, commonly with small wings issued on one side which continue into the vesicle base.

In molecular and morphological studies of Indo-Pacific species, Mattio et al. (2009, 2010) recognized the morphological variability of S. aquifolium and proposed the following as being synonyms: S. binderi , S. crassifolium , S. echinocarpum J. Agardh (1848: 327) , S. biserrula J. Agardh (1848: 318) , S. heterocystum Montagne (1842: 250) , S. odontocarpum Sonder (1871: 43) , S. oocyste J. Agardh (1848: 317) , and S. spathulaefolium var. neocaledonicum Grunow (1916: 22) , among others.

Materials examined:—78EM-18 (58 and 59).

* Sargassum polycystum C. Agardh (1824: 304)

Type:— Sunda Strait , Indonesia .

Remarks:—This species is among the easiest to identify on the basis of vegetative morphological grounds, particularly its rough and spinous main branches which make field identification rather easy ( Modelo & Umezaki 1995). Most authors working in the Indo-Pacific region have highlighted the muricate nature of the main branches, described as beset with short spines ( Tsutsui et al. 2005, Ohba et al. 2007) which are simple or Y-shaped ( Trono 1997, Coppejans et al. 2009, 2010). It was Chiang et al. (1992) who first studied the details of these surface protuberances and found that they are elongate cryptostomata. Kraft (2009) gave a more detailed description of these ostiolate structures leading to shallow pits containing trichothallic hairs. These unique cryptostomata are issued radially ( Kraft 2009) or alternately ( Ohba et al. 2007) from the main branches.

Chou & Chiang (1981) remarked that one of the most distinctive features of this species is the ”existence of creeping branches of rhizoidal system” issued from the lower portion of the main axis and used to attach the mature thalli secondarily. However, this was not found in the materials on hand. The secondary attachment of the thalli by means of stoloniferous structures in S. polycystum brings to mind a similar mechanism seen in S. stolonifolium Phang & Yoshida (1997: 61) . In the latter, however, attachment is accomplished by modified cauline leaves issued near the base and which are well developed into stolons especially among plants collected from habitats with strong waves ( Ajisaka & Lewmanomont 2004). In places which are protected from strong wave action, the cauline leaves are issued but do not usually develop into stolons. This distinctive mode of secondary attachment from leaves was the main criterion used for recognizing S. stolonifolium . Based on morphological grounds, Mattio et al. (2010) placed S. stolonifolium under the synonymy of Sargassum plagiophyllum Mertens ex C. Agardh (1824: 304) . On the other hand, both S. stolonifolium and S. polycystum were shown to be sister species based on ITS-2 data ( Yoshida et al. 2004).

Materials examined:—78EM-13 (96, 108 to 114), 78 EM-18 (454).

* Sargassum siliquosum J. Agardh (1848: 316)

Type:— Singapore .

Remarks:—Aside from other distinctive features, Trono (1997) emphasized the morphology of the female receptacles as definitive for this species. The female receptacular branches in this species have triquetrous and twisted forms, while in S. baccularia ( Mertens 1819: 177) C. Agardh (1824: 304) , the fertile branches are triquetrous but never twisted. Modelo & Umezaki (1995) highlighted the male and female receptacular branches in sexually matured plants which are often as long as the leaves themselves. Unfortunately, the materials under study are sterile and cannot be verified using the feature mentioned above. The identification is however based on other morphological similarities such as leaf shape and dimensions, leaf margins and midrib features and vesicular measurements. At best, this remains a tentative identification.

This species is widely distributed throughout Southeast Asia. In a biogeographical analysis of Sargassum species in the South China Sea region, S. siliquosum is among the most widely and commonly recorded species except in the colder waters off Hong Kong ( Ang et al. 2008). Within Philippine waters, it is also one of the most commonly encountered species ( Trono 1997).

Materials examined:—78EM-12 (154, 155), 78EM-14 (19), 78EM-18 (452, 453).

* Turbinaria conoides (J. Agardh) Kützing (1860: 24)

Basionym: Turbinaria vulgaris var. conoides J. Agardh (1848: 267)

Type:—‘in mari Indico ad oras Hindostaniae, ad Chinam, ad Zeylonam, ad littus occidentale Novae Hollandiae’.

Remarks:—This species is distinguished from others in the genus by the conspicuous absence of intramarginal crown teeth on the distal surfaces of the foliar branches. The inflated foliar branches are irregularly rounded to somewhat cordate when seen from above with a smooth distal surface owing to the absence of intramarginal crown teeth. The margins are lined with uniformly coarse teeth. This morphology is considered to be the typical form.

Another form encountered in the study area is characterized by the absence of intramarginal crown teeth, but instead of a circular outline of the distal foliar branches as noted above, the blade has a distinctly retuse portion giving the impression of an imperfect acetabulum. Sometimes the blade approaches the peltate condition while on one hand the blade may be oriented almost vertically resulting in a flabellate, toothed blade. This particular form is herein determined as T. conoides f. laticuspidata W.R. Taylor (1964: 481) which was first described based on materials collected from Cebu Island. The form has been collected from a few sites around southern Philippines and appears to be a Philippine endemic.

Materials examined:— f. conoides 78EM-13 (68 and 69), f. laticuspidata 78EM-12 (99 and 100), 78EM-

20 (49).

* Turbinaria decurrens Bory de Saint Vincent (1828: 119)

Type:—in the sea between Tahiti and New Guinea .

Remarks:—This is one of the most distinctive species of Turbinaria with its 3-sided, obpyramidal foliar branches that appear triangular from top view. The longitudinal edges and base of the inverted pyramid have numerous fine serrations. Another species that closely resembles T. decurrens in general foliar morphology is T. murrayana Barton (1891: 218) . In her original description, Barton (1891) differentiated it from T. decurrens by its ”having a short, thick, unbranched stem, in the absence of vesicles (embedded within the foliar branches) and the arrangement of the receptacles”’ Only small vesicles have been found within older foliar branches of the materials under study, while receptacles are racemose in contrast to a corymbose arrangement in T. murrayana . Coppejans et al. (2010) observed a progressive loss of older foliar branches towards the base of the plant resulting in bare stipes with leaf scars. In addition, they observed that foliar branches formed five clearly separated vertical rows along the main axis, a feature not seen in the materials on hand. Without doubt, both names have been applied interchangeably to Turbinaria species in the Indo-Pacific showing obpyramidal morphology.

Some specimens examined anchor themselves on some sponges (78EM-14 (1430)) and small rocks (78EM-14 (138 and 142)) while in the specimen 78EM-14 (138) the tip of a branched hapter is transformed into an adherent disk.

Materials examined:—78EM-14 (135 to 144).