Phylactolaemata, Allman, 1856

Wood, Timothy S., 2022, Phylactolaemate bryozoans at the Zoological Survey of India and a taxonomic key to Indian Phylactolaemata, Zootaxa 5200 (2), pp. 401-435 : 429-430

Taxonomic key to Indian Phylactolaemata

1 Zooids arranged in clusters, individual colonies gelatinous, body wall colorless and transparent; floatoblast length> 0.7 mm, annulus curved along the two axes like a saddle; sessoblasts absent. Lophopodidae ................................. 2

- Zooids arranged serially along branching tubules; body wall variable; floatoblast length <0.7 mm, annulus not curved on two axes; sessoblasts may be present......................................................................... 4

2 Individual colonies reaching diameter of 1.5–2.0 cm, compound colonies can be much larger; statoblasts roughly circular with very small hooks around the entire perimeter. ( Fig. 18 c, d ).......................... Asajirella gelatinosa ( Oka, 1890)

- Individual colonies seldom more than 1 cm diameter; statoblasts broadly oval with any hooks or spines restricted to the two polar regions ( Fig. 18a, b ). Lophopodella .................................................................. 3

3 Floatoblast dorsal fenestra with prominent radiating ridges ( Fig. 18a )................ Lophopodella carteri ( Hyatt, 1866)

- Floatoblast dorsal fenestra without prominent radiating ridges ( Fig. 18b ).......... Lophopodella thomasi Rousselet, 1904

4 Lophophore formed by a ring of tentacles of equal length; mature statoblasts bean-like, lacking an annulus for buoyancy or a thin collar around the periphery. Fredericella ............................................................... 5

- Lophophore tentacles not equal in length, arranged in the form of a double U; statoblasts either floatoblasts (unattached, with annulus inflated for buoyancy) or sessoblasts (firmly attached to substratum, anulus not inflated)..................... 10

5 Statoblast outer surface perfectly smooth, appearing shiny when dry and observed with reflected light................. 6

- Statoblast outer surface appearing dull (not shiny) when dry and observed with reflected light........................ 8

6 Statoblast encircled by a minutely toothed keel at the suture ( Fig. 13 ).................... Fredericella carinata sp. nov.

- Statoblast without a keel at the suture..................................................................... 7

7 Statoblast frontal valve perfectly smooth and unmarked..................... Fredericella sultana ( Blumenbach, 1779)

- Statoblast frontal valve bearing a faint stippled pattern, especially near the center.................................................................................................. Fredericella toriumii Hirose & Mawatari, 2011

8 Statoblast frontal valve surface bearing a uniform, minute reticulation, often with thickened walls to give the impression of small depressions, like a golf ball........................................................................ 9

- Statoblast surface bearing a persistent, finely wrinkled membrane that disappears after treatment with hot alkali.................................................................................. Fredericella browni ( Rogick, 1945)

9 Reticulation fading towards the suture ( Fig. 1a, c, d )............................ Fredericella indica Annandale, 1909 .

- Reticulation uniform across entire frontal valve, including suture area ( Figs. 1b , 12b )........ Fredericella borealis sp. nov.

10 Floatoblast dorsal fenestra mostly smooth, ventral fenestra reticulated or partially so.............................. 11

- Floatoblast dorsal and ventral fenestrae tuberculated........................................................ 12

11 Floatoblast elongate ( Table 1 ), floatoblast ventral fenestra strongly reticulated ( Fig 4b ), sessoblast frontal valve with a sharply defined tubercle within each interstice of a reticulum ( Fig 4c, d ); colony variable) Plumatella bombayensis Annandale (1908)

- Floatoblast broadly oval (see Table 1 ), floatoblast ventral fenestra often not fully reticulated ( Fig. 16a, b ); sessoblast frontal valve either heavily reticulated or with irregular, lumpy surface ( Fig 16c ); colony forming loose mat of tangled tubules not closely adherent to the substratum................................................ Plumatella paltensis sp. nov.

12 Floatoblast length LESS than 450 µm, floatoblast dorsal valve either flat or convex............................... 13

- Floatoblast length MORE than 450 µm, floatoblast dorsal valve conspicuously concave ( Figs. 2a, b ; 5a, b ; 20a )................................................................................. Hyalinella lendenfeldi ( Ridley, 1886)

13 Floatoblast ventral fenestra relatively large, its length more than half overall floatoblast length...................... 14

- Floatoblast ventral fenestra relatively small, its length less than half overall floatoblast length; sessoblast frontal valve heavily tuberculated, sometimes with large, irregular lumps arranged in a circle between the center and the annulus; sessoblast annulus wide and reticulated ( Fig. 20h )............................................... Varunella coronifera Wiebach, 1974

14 Floatoblast dorsal fenestra length MORE than half floatoblast length.......................................... 15

- Floatoblast dorsal fenestra length LESS than half floatoblast length............................................ 21

15 Floatoblast length greater than 350 um; fenestrae bearing tubercles or reticulation................................ 16

- Floatoblasts length less than 350 um; outline broadly oval to nearly circular, fenestra tubercles showing with hypertubercles seen with SEM ( Fig. 9 )............................................ Rumarcanella himalayana ( Annandale, 1911)

16 Floatoblast dorsal fenestra bearing tubercles, sessoblast frontal valve also with tubercles........................... 17

- Floatoblast dorsal fenestra strongly reticulated, tubercles absent; sessoblast with reticulation that may thicken so that enclosed cells resemble a uniform field of small holes................................... Plumatella vaihiriae Hastings, 1929

17 Dorsal fenestra bearing tubercles only, without reticulation................................................... 18

- Dorsal fenestra bearing reticulation with a single tubercle in the center of each cell; Floatoblast annulus bearing tubercles, visible only with scanning electron microscopy ( Fig. 3a, b )......................... Plumatella fungosa ( Pallas, 1768)

18 Floatoblast dorsal fenestra tubercles well-spaced, not crowded................................................ 19

- Floatoblast dorsal fenestra tubercles so crowded that small spaces between them appear as either pores or bright points of light, depending on the focal plane ( Fig. 20d )...................................... Plumatella javanica Kraepelin, 1906 .

19 Floatoblast polar grooves practically inconspicuous when isolated dorsal valve is viewed with substage lighting......... 20

- Floatoblast polar groves encroach conspicuously over the capsule at both poles ( Fig. 20i ). Varunella indorana Wiebach, 1974

20 Floatoblast dorsal fenestra elongate, length/width>1.5 ( Fig. 20c )...................... Plumatella casmiana Oka, 1907

- Floatoblast dorsal fenestra, length/width <1.5 ( Fig. 20e )...................... Rumarcanella vorstmani ( Toriumi, 1952)

21 Edge of floatoblast appears smooth, without small knobs or spines............................................. 22

- Edge of floatoblast with small knobs or spines protruding from the suture. Swarupella ............................. 24

22 Floatoblast length/width> 1.3, sessoblast annulus thin, blade-like............................................. 23

- Floatoblast length/width <1.3; sessoblast annulus thick and uniquely cellular ( Fig. 17 )........... Plumatella raoi sp. nov.

23 Twice the floatoblast dorsal fenestra width is MORE than floatoblast width ( Fig. 11 ). Rumarcanella indica Annandale, 1909

- Twice the floatoblast dorsal fenestra width is LESS than floatoblast width ( Fig. 6a )........ Plumatella mukai Wood, 2001

24 Floatoblasts tapering to acutely rounded poles; fragile, weakly sclerotized, colorless, almost membranous; dorsal fenestra relatively small, the width less than half overall floatoblast width ( Fig. 20f ).. Swarupella andamanensis ( Shrivastava, 1981)

- Floatoblasts broadly oval, not tapering at each end; not fragile, membranous, or colorless; dorsal fenestra relatively large, the width more than half floatoblast width ( Fig. 20g )................................... Swarupella divina Wood, 2006 .

Figures

FIGURE 1. Fredericella statoblast valves with pitted exterior. (a) Fredericella indica statoblast valve showing a smooth surface at the ends, from Annandale’s type specimen, ZSI 3479, valve has curled upon drying; (b) Fredericella borealis showing pitted surface at the ends, from Magerøya Island, Norway; (c) Fredericella indica, lateral view showing smooth region near the suture, from NHMUK 1914.10.2.1, Colombo, Sri Lanka; (d) Enlargement of previous photo; (e) Enlarged view of suture area of F. borealis from Illinois, USA, showing reticulation extending to the suture. Scale bars for a–c = 100 µm, scale bars for d–e = 20 µm.

FIGURE 3. Statoblasts from specimen P92 labeled Plumatella bigemmis (Holotype), now identified as Plumatella fungosa. a) Floatoblast valves with dorsal valve above, ventral valve below; b) Scanning electron micrograph of floatoblast ventral valve with inset showing tubercles on the annulus; c) Scanning electron micrograph of sessoblast with inset showing tubercles on annulus. All scale bars = 100 µm.

FIGURE 4. Plumatella bombayensis. Statoblasts from ZEV 3804, Zoological Gardens, Kolkata. (a) Floatoblast dorsal valve showing small, unmarked fenestra; (b) Floatoblast ventral valve showing pronounced fenestra reticulation; (c) Sessoblast showing reticulation in which each cell bears a single tubercle; (d) Partial enlargement of previous image. Scale bars for a–c = 100 µm, scale bar for d = 20 µm.

FIGURE 5. Plumatella longigemmis. Statoblasts from specimenP47 labeled Plumatella longigemmis (syntype), now recognized as Hyalinella lendenfeldi. (a) Floatoblast valves with dorsal valve on the left; (b) SEM image showing the floatoblast dorsal side in greater detail. Scale bars = 100 µm.

FIGURE 6. Plumatella mukaii. (a) Floatoblast valves from P1184, scale bar = 100 µm; (b) SEM image from P1179 showing floatoblast asymmetry, scale bar = 100 µm; (c) Floatoblast SEM image from P1179 showing wrinkled texture, scale bar = 30 µm.

FIGURE 9. Stolella himalayana, holotype, now Rumarcanella himalayana, Specimen No. P1388. (a) Floatoblast valves, scale bar = 100 µm; (b) SEM image of a floatoblast dorsal valve; (c) close-up of a portion of the floatoblast fenestra showing hypertubercles, the key feature of the genus Rumarcanella, scale bar = 10 µm; (d) Floatoblast suture showing the very lumpy structure; (e) Detail of the floatoblast profile showing the serrated appearance, scale bar = 10 µm.

FIGURE 11. Stolella indica, holotype (now Rumarcanella indica). (a) Floatoblast valves from ZEV3482/7, scale bar = 100 µm; (b) SEM image showing hypertubercles on a portion of the floatoblast dorsal fenestra, scale bar = 25 µm.

FIGURE 12. Fredericella borealis n. sp. (a) A fragment of the holotype colony showing free branches and several statoblasts, scale bar = 3 mm; (b) A pair of separated valves showing reticulation extending to the suture, scale bar = 100 µm.

FIGURE 13. Fredericella carinata n. sp. (a) Pair of statoblast valves, scale bar = 100 µm; (b) Closer view with SEM showing a portion of the carina, scale bar = 30 µm; (c) Similar feature in Fredericella crenulata, scale bar = 15 µm.

FIGURE 16. Plumatella paltensis n. sp. (a) Statoblasts from P1198 shown with light microscopy, from top to bottom:floatoblast dorsal valve, floatoblast ventral valve, sessoblast frontal valve; (b) SEM micrograph of floatoblasts from ZEV 4800, dorsal on left, ventral on right, scale bar = 100 µm; (c) SEM view of sessoblast from ZEV 4800 with magnified image on the right. Scale bars for all images = 100 µm.

FIGURE 17. Plumatella raoi n. sp. (a) Two sessoblasts showing unusual cellular annulus and heavily tuberculated frontal valve, scale bar = 100 μm; (b) Closer view of sessoblast annulus, scale bar = 10 μm; (c) SEM images of floatoblast valves with dorsal valve on the left, scale bar = 100 µm; (d) Enlargement of a portion of previous image showing hypertubercles and porelike structures; (e) Floatoblast valves with dorsal valve on the left, scale bar = 100 μm; (f) sessoblast valves with frontal valve on the left, scale bar = 100 μm.

FIGURE 18. Lophopodidae statoblasts. (a) Lophopodella carteri; (b) Lophopodella thomasi; (c) Asajirella gelatinosa; (d) Peripheral spines on statoblast of A. gelatinosa. Scale bar for a–c = 500 µm; scale bar for d = 50 µm.

FIGURE 20. Miscellaneous floatoblasts. (a) Hyalinella lendenfeldi; (b) Plumatella fruticosa not from India; (c) Plumatella casmiana; (d) Plumatella javanica; (e) Rumarcanella vorstmani; (f) Swarupella andamanensis; (g) Swarupella divina; (h) Varunella coronifera; (i) Varunella indorana. Scale bar = 100 µm. Figure (i) modified from Wiebach, 1974.

FIGURE2. Floatoblastvalvesof Hyalinella indica, nowidentified as Hyalinellalendenfeldi. (a)Valvesfrom thelectotype,ZEV/7 6750; (b) Floatoblast of confirmed H. lendenfeldi from Thailand showing unique concave dorsal valve. Scale bars = 100 µm.