• Category
  • Length Range
    47-86 µm
  • Width Range
    13-18 µm
  • Striae in 10 µm
    15-22
  • Reported As
    Mastogloia frickei (Paddock and Kemp 1990, pg. 63, Figs 36 a,b)
    Mastogloia frickei (Siqueiros-Beltrones et al. 2020, p. 8, Fig 13 a,b)
    Mastogloia frickei (Witkowski et al. 2000, pg. 248, Pl. 76, Fig 1)

Identification

Description

In girdle view, frustules are rectangular with rounded corners at the valve apices and isomorphic, rectangular partecta extending to near the apices (partecta density = 11–14 in 10 μm, n =21). Valves are broadly lanceolate (smaller cells) to rhombic (larger cells) with apiculate apices. The axial area is narrow and gradually expands to become asymmetric around an undifferentiated central area. A small central nodule is evident as a bright area, when focusing on valve interior. External raphe branches are sinuous. External proximal raphe ends are unilaterally curved and eccentric around the central area. The proximal raphe ends are very closely spaced. Ornamentation of the valve is in a pattern of a paraxial zone of parallel (valve middle) to convergent (most of length) alveoli and a lateral zone of radiate alveoli that extends to the valve margin. Longitudinal rows of alveoli are separated by unornamented areas. Partecta are transapically elongated, rectangular (width = 1.8–2.5 μm) with very slightly convex inner margins. Terminal partecta are distinct in that they are slightly longer, with rounded inner margins.

Valves have two sets of alveoli on the valve face. Near the axial area, the alveoli are parallel becoming convergent and open externally by single pores, separated from the outer alveoli by unperforated lateral areas. Outer alveoli open externally by single pores on the mantle.

This taxon is distinguished from Mastogloia frickei in having only one longitudinal row of external alveoli openings on each hemivalve valve face, alveolus openings on the internal valve face in the form of pore fields, and transapically-elongated partecta versus two longitudinal rows of external alveoli openings on each hemivalve valve face, alveolus openings on the internal valve face in the form of single pores, and nearly square-partecta for Mastogloia frickei.

This taxon has been frequently reported as Mastogloia frickei (Paddock and Kemp 1990, pg. 63, Figs 36a, b; Frankovich and Wachnicka 2015, p. 249; Siqueiros-Beltrones et al. 2020, p. 8, figs 13 a, b., Witkowski et al. 2000, pg. 248, Pl. 76, Fig. 1) and as Mastogloia sp. cf. frickei (Loir and Novarino 2013, pg. 51, Pl. 25a).

Autecology

The ranges of the morphological measurements (i.e., length, width, stria density) were produced from observations reported in Hein et al. 2008 (Bahamas), Loir and Novarino 2013 (Caribbean Sea), Siqueiros-Beltrones et al. 2020 (Gulf of Mexico), and Lobban and Frankovich 2023 (Florida).

This taxon has been observed as a marine epiphyte on seagrasses, macroalgae, and other benthic substrates in the warm waters of the Gulf of Mexico, Caribbean Sea, and the tropical and subtropical northwest Atlantic Ocean. Observations are so far limited to water depths less than 10 meters.

Original Description

Description – LM morphology:

In girdle view, frustules rectangular with rounded corners at valve apices and isomorphic rectangular partecta of valvocopulae extending to near apices (partecta density = 11–14 in 10 μm, n =21). Valves broadly lanceolate (smaller cells) to rhombic (larger cells) with cuneate sub-rostrate apices (Figures 2B, 7A, C, E). Valve measurements: length 49–86 μm, width 14–17 μm, length to width ratio 3.4–5.5, n =21. Axial area narrow, gradually expanding and becoming asymmetric around undifferentiated central area (Figure 2B). Small central nodule evident as bright area when focusing on valve interior (Figures 7B, D, E). External raphe branches sinuous (Figures 7A, C, F). External central raphe ends unilaterally curved and eccentric around central area (Figures 8A, C). Central raphe ends very closely spaced (Figures 2B, 7A, C). Valve pattern forming 2 zones within each hemivalve, a paraxial zone of parallel (valve middle) to convergent (most of length) alveoli and a lateral zone of radiate alveoli that extends onto valve margin, 15–17 in 10 μm. Longitudinal rows of alveoli separated by unornamented areas (Figures 2B, 7A, C, E). Partecta transapically elongated, rectangular (width = 1.8–2.5 μm) with very slightly convex inner margins, 11–14 in 10 μm (Figures 7B, C, F); terminal partecta distinct from rest, slightly longer with rounded inner margins.

Description – SEM morphology:

Valve faces slightly undulate with depression at valve middle and slightly elevated on each side of middle depression (Figures 8A, B). External valve face with single sinuous row of small, ovoid to dash-like pores on inner margins of paraxial alveoli, following contours of raphe branches (Figures 8A, C). Single linear row of small dash-like external alveolar openings on outer margins of marginal alveoli on mantle (Figures 8B, D black arrow). Paraxial and marginal alveoli separated by unornamented areas (Figure 8C). Moderately deep mantle gradually sloped at depressed valve middle and more steeply sloped towards apices without a distinct transition between valve face and mantle (Figure 8B). Sinuous raphe branches within narrow axial area, becoming unilaterally arcuate and slightly elevated from valve face in central area (Figures 8A, C). External central raphe ends terminating very close to each other (Figure 8C). External apical raphe ends simple, deflected towards the same side of valve as central raphe ends, extending onto valve mantle and terminating at margin (Figures 8B, D).

Internally, 1 to 2 rows of irregularly arranged punctate pores present on outer margins of each paraxial alveolus and on inner margins of each marginal alveolus (Figures 9A, C, and D). Areas between the internal alveoli pores unornamented (Figures 9C, D). A longer, apically elongated dash-like pore present just below valve margin at terminus of each marginal alveolus (Figure 9D arrow). Internal raphe branches straight (Figures 9A, C). Internal central raphe ends straight, simple, closely spaced (Figure 9C). Internal apical raphe ends simple, straight, surrounded by small helictoglossae (Figures 9B, E). Cingulum consisting of closed partectate valvocopulae and an additional unornamented open copula (Figures 8B, 9F). Each partectum perforated by six transapical linear rows of very small poroids (Figures 9B, F). Valvocopula with shallow septa at apices connecting with partectal ring (Figures 9B, E). Externally, partecta exit pores comma-shaped (Figures 9B, F), inner margin convex (Figure 9A).

Diagnosis – Valves with two sets of alveoli on the valve face, those near axial area parallel becoming convergent, opening externally by single pores adjacent to the raphe, separated from outer alveoli by unperforated lateral areas. Outer alveoli open externally by single pores on the mantle. Distinguished from Mastogloia frickei in having only one longitudinal row of external alveoli openings on each hemivalve valve face, alveolus openings on the internal valve face in the form of pore fields, and transapically-elongated partecta versus two longitudinal rows of external alveoli openings on each hemivalve valve face, alveolus openings on the internal valve face in the form of single pores, and nearly square-partecta for Mastogloia frickei.

  • Author
    Lobban and Frankovich 2023
  • Length Range
    49-86 µm
  • Width
    14-17 µm
  • Striae in 10µm
    15-17

Original Images

Mastogloia floridensis orig illus1
Mastogloia floridensis orig illus2
Mastogloia floridensis orig desc

Cite This Page

Frankovich, T., Lobban, C. (2023). Mastogloia floridensis. In Diatoms of North America. Retrieved May 29, 2024, from https://diatoms.org/species/mastogloia-floridensis

Responses

The 15 response plots show an environmental variable (x axis) against the relative abundance (y axis) of Mastogloia floridensis from all the stream reaches where it was present. Note that the relative abundance scale is the same on each plot. Explanation of each environmental variable and units are as follows:

ELEVATION = stream reach elevation (meters)
STRAHLER = distribution plot of the Strahler Stream Order
SLOPE = stream reach gradient (degrees)
W1_HALL = an index that is a measure of streamside (riparian) human activity that ranges from 0 - 10, with a value of 0 indicating of minimal disturbance to a value of 10 indicating severe disturbance.
PHSTVL = pH measured in a sealed syringe sample (pH units)
log_COND = log concentration of specific conductivity (µS/cm)
log_PTL = log concentration of total phosphorus (µg/L)
log_NO3 = log concentration of nitrate (µeq/L)
log_DOC = log concentration of dissolved organic carbon (mg/L)
log_SIO2 = log concentration of silicon (mg/L)
log_NA = log concentration of sodium (µeq/L)
log_HCO3 = log concentration of the bicarbonate ion (µeq/L)
EMBED = percent of the stream substrate that is embedded by sand and fine sediment
log_TURBIDITY = log of turbidity, a measure of cloudiness of water, in nephelometric turbidity units (NTU).
DISTOT = an index of total human disturbance in the watershed that ranges from 1 - 100, with a value of 0 indicating of minimal disturbance to a value of 100 indicating severe disturbance.