Rhabdopleura, Allman, 1869

Gordon, Dennis P., Randolph Quek, Z. B. & Huang, Danwei, 2024, Four new species and a ribosomal phylogeny of Rhabdopleura (Hemichordata: Graptolithina) from New Zealand, with a review and key to all described extant taxa, Zootaxa 5424 (3), pp. 323-357 : 352-353

Dichotomous key to all described species of Rhabdopleura based on morphology

1. Mature colony tiny, compact, subcircular, not> 3 mm diameter, adherent tubes closely appressed laterally..... R. compacta - Mature colony ramifying, occupying> 4 mm of lateral spread................................................. 2

2. Relative to creeping tube, inception of ringed erect tubes indirect, terminal, each arising from short blind-ending side branches budded from sides of creeping tubes...................................................................... 3

- Relative to creeping tube, inception of ringed erect tubes direct, i.e. borne directly on and projecting from ramifying creeping tubes or stems....................................................................................... 7

3. Erect tubes large, up to 11‒12 mm tall and 1 mm diameter with aligned longitudinal striations and fusellar rings in 8‒10 annular panels....................................................................................... R. striata

- Erect tubes much shorter and thinner, with no striations or panelling of fuselli..................................... 4

4. Dark pectocaulus typically transparent where it diverges and widens into an adherent short side branch; visible side walls of pectocaulus then appear as two thin lines converging towards base of ringed tube......................... R. grimaldii

- Dark pectocaulus visibly continuous into short side branches, side walls not converging towards base of ringed tube...... 5

5. Short blind-ending side branches budded 1‒2 mm distant from one another....................... R. chathamica n. sp.

- Short blind-ending side branches typically budded relatively close (<1 mm) to each other........................... 6

6. Erect ringed tubes 118‒131 μm diameter, fusellus height 11‒24 μm.................................. R. manubialis

- Erect ringed tubes 143‒154 μm diameter, fusellus height 24‒41 μm..................................... R. normani

7. Colony occurring in/on mud, creeping tube lacking oblique sutures, erect tubes up to 6‒7 mm long........... R. mirabilis

- Colony attached to hard substratum or growing freely into water column......................................... 8

8. Mature colony growing 3-dimensionally into water column, branching tubes lacking oblique fusellar sutures................................................................................................ R. emancipata n. sp.

- Mature colony ramifying on/in hard substrata.............................................................. 9

9. Smooth creeping tubes adherent to interiors of bryozoan zooids, no septa separating individual zooids........ R. recondita

- Smooth creeping tubes attached to hard exterior surfaces, zooids pertaining to erect ringed tubes separated by septa...... 10

10. Width (diameter) of erect ringed tube similar to creeping-tube convexity................................ R. annulata

- Width (diameter) of erect ringed tube less than half that of creeping tube........................................ 11

11. Number of fusellar collars in 500 μm of erect-tube length 10‒12, mean fusellus height 40 μm, zigzag sequence ½ ‒ ¾ width of creeping-tube.......................................................................... R. francesca n. sp.

- Number of fusellar collars in 500 μm of erect-tube length 12‒20, mean fusellus height 32 μm, zigzag sequence ⅓ ‒ ½ width of creeping tube.......................................................................... R. decipula n. sp.