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Volume 86, 1959
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Genus Mastogloia Thwaites in W. Sm., 1856, 63

Valves similar, orbicular, linear, elliptical, lanceolate or rhombic, with obtuse, acute or ostrate ends; axial area narrow or indistinct; central area usually small; median line straight or undulate; striae punctate, the puncta usually in longitudinal or decussate lines; a septate plate divided into loculi is found between the connective zone and the valve, next to the margin; plastids two, each consisting of a band with its centre at the apex, and extending on both valves toward the centre, with a sinus on the middle of the band at its upper part; a pyrenoid between the folds of each band.

Key to the Species of Mastogloia
1. Valves typically elliptic, with broadly rounded, rarely constricted ends 2.
Valves more or less lanceolate, or elliptic with rostrate or acute ends 4.
2. Frustules radially punctate M. cribrosa. 3.
Frustules with a network of areolae
3. Areolae in strongly radial rows, in the middle alternately long and short M. cocconeiformis.
Areolae almost parallel to the transapical axis, those in the middle of even length M. horvathiana.
4. Valves slightly constricted on transapical axis M. rostellata.
Valves rhombic-lanceolate, loculi small, numerous (38–40) M. strigilis.
Valves ovate to ovate-lanceolate with acute apices, loculi large and few (18–20) M. quinquecostata.
Valves rostrate or at least constricted near apices 5.
5. Transapical ribs light, longitudinal lines weak M. smithii.
Transapical ribs marked, longitudinal lines evident M. gracilis.

231. Mastogloia cribrosa Grun. (Pl. 6, Fig. 87.)

Grun., 1860, 577, 7, 10c.

Hust., 1931–33, 468, 887.

Cells solitary, often enclosed in a gelatinous sheath, frustule in valve view broadly elliptic, with usually twelve loculi; central nodule small. Raphe straight or very slightly curved; striae radial, areolate or coarsely punctate. Length, 30μ.

Distribution. Estuarine; marine; epontic. Frequent from algae, sea grasses, and fouling test plates. Australia: Heron Island. Botany Bay, Port Hacking, Conjola, Mallacoota. New Zealand: Lake Ellesmer.

232. Mastogloia strigilis Hust. (Pl. 1, Fig. 9.)

Hust., 1937, 541, 974.

Cells solitary; frustule in valve view rhombic-lanceolate with bluntly rounded ends, depressed on either side of the mid-line, with from 38 to 40 loculi; raphe straight, central area very narrow; surface with transverse moniliform striae of interrupted puncta. Length, 60–75μ.

Distribution. Estuarine, mesohaline, epiphytic, found on Zostera. Frequent but not abundant. Australia: Lake Macquarie.

233. Mastogloia quinquecostata Grun. (Pl. 6, Fig. 88a. b; Pl. 7, Fig. 88c.)

Grun., 1860, 578, 7, 8.

Hust., 1931–33, 556, 989 (synonymy).

Cells solitary; frustule in valve view linear-elliptic, with acute ends, with 18 to 20 loculi reaching practically to the apices. Raphe somewhat undulate; valve surface with transverse striae, puncta forming longitudinal striae, usually farther apart than the transverse striae; on each side of the median line are several longitudinal depressions which lack longitudinal striae. Length, 55–80μ.

Distribution. Estuarine; euryhaline; benthic, epontic on algae, sea grasses, and fouling test plates Australia: Heron Island, Moreton Bay, Lake Macquarie, Port Jackson, Botany Bay, Port Hacking, Lake Conjola, Lake Coila, Eden, Mallacoota. Port Phillip. The most common member of this genus. New Zealand: Wellington (Wainui).

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234. Mastogloia gracilis Hust. (Pl. 1, Fig. 10.)

Hust., 1931–33, 507, 933.

Cells solitary; frustules in valve view elliptic-lanceolate with constricted apices; raphe slightly undulate, well defined; loculi 24 to 28; surface with strong transverse striae, crossed by faint longitudinal striae, which are usually somewhat undulate. Length, 40–50μ.

Distribution. Estuarine; mesohaline, epontic on Zostera. Australia: Port Hacking, Lake Macquarie. Infrequent.

235. Mastogloia smithii Thwaites (Pl. 1, Fig. 11..)

Thwaites in W. Sm., 1856, 65, 54, 341.

Boyer, 1916, 87, 17, 19.

Hust., 1931–33, 502, 928, a.

Cells solitary; frustules in valve view elliptic-lanceolate, subrostrate; raphe straight; loculi usually 6 to 9 ending some distances from the apices; central area more or less oval; surface striate, striae transverse, punctate; puncta forming longitudinal rows. Length, 30–60μ.

Distribution. Estuarine, euryhaline; benthic. Australia: Port Hacking, Lake Conjola, Lake Macquarie, Botany Bay.

236. Mastogloia cocconeiformis Grun. (Pl. 6, Fig. 90; Pl. 1, Fig. 12.)

Grun., 1860, 578, 7, 14.

Hust., 1931–33, 469, 888

Cells elliptical, almost circular; raphe slightly curved; axial area very narrow, central area small, circular to elliptic; valves evenly areolate, areolae hexagonal, forming a net in a three-directional system; loculi narrow, rectangular, reaching apices. Length, 25–60μ.

Distribution. Australia: Lake Macquarie and Lake Conjola.

237. Mastigloia horvathiana Grun. (Pl. 6, Fig. 89; Pl. 1, Fig. 13.)

Grun., 1860, 578, 7, 13.

Hust., 1933, 471, 890.

Valves broadly elliptic with cuneate ends; raphe curved, gap varying in width; axial area very narrow, central area small, rounded; valve surface evenly areolate, irregularly hexagonal forming two-directional system, areolate nearest raphe transversely elongate; loculi radially elongate, reaching apices. Length, 50μ.

Distribution. Australia: Heron Island.

238. Mastogoloia rostellata Grun. (Pl. 1, Fig. 14.)

Grun., 1877, 174, 195, 2.

Hust., 1931–33, 485, 907.

Cells broadly linear-lanceolate, constricted near apices and centrally; raphe straight, areas narrow; valve surface evenly areolate, areolae elongated transapically, arranged in a three-directional system; loculi narrow, varying in size, elongated apically, inner border convex. Length. 40–60μ.

Distribution. Australia: Port Hacking.

The following species of Mastogloia have been recorded previously:—

  • M. elliptica (Agh.) Cl., 1895 (A. S., 1893, 185, 5–7). Australia.

  • M. exigua Lewis, 1861 (Petit, 1877, 26.) Lyall Bay.

  • M. inaequalis Cl., 1895. (Boyer, 1927, 334.) Australia.

  • M. jelineckii Grun., 1867 (Navicula quarnerensis Grun. v dilatata Petit. (Petit, 1877.) Foveaux Strait.

  • M. macdonaldii Grev., 1865. Type loc., Australia.

  • M. marginulata Grun., 1868. (A.S., 1893, 186, 30; Boyer, 1927, 335). New Zealand.

  • M. rhombus (Petit) Cl., 1894 (as Navicula rhombus Petit, 1877). (Petit, 1877.) New Zealand.

  • M. splendida (Greg.) Cl., 1895. (As Orthoneis.) (Gr. & St., 1887.) Oamaru.

  • Navicula trilineata of Gr. & St., 1887, may also be a species of Mastogloia.

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