SPECIES, Dumeril, 1805

SPECIES View in CoL KEY

1a An entire valve surface firmly attached to a substrate. Subconical. Inarticulate (no hinge) and with holoperipheral growth: ........................................................................................................................ 2

1b Shell articulated and with stalk (pedicle) posteriorly: ........................................................................................................................................... 3

2a Small, non-punctate shell, up to 8 mm long, with long setae radiating out from valve margin. Subcircular outline. Rather thin, chitinophosphatic and whitish, yellow to brown or blackish-brown shell: ............................................................................................................... Pelagodiscus atlanticus ( King, 1868)

2b Up to 25 mm wide, endopunctate shell, without setae. Transverse subangular outline. Calcium carbonate shell. Whitish to greyish or reddish brown: .................................................................... Novocrania anomala ( Müller, 1776)

3a Shell not punctate. Deltidial plates (red) not meeting: ...................................................................................................................... 4

3b Shell endopunctate (fine pitting in shell): ................................................................................................................................................................ 6

4a Slightly unisulcate anterior and gently S-shaped lateral commissure. No ornamentation and colourless or with a yellow tint. Small ( 6 mm). High internal dorsal median septum: .......................................................................................................................... Cryptopora gnomon Jeffreys, 1869a

4b Moderate size ( 25–29 mm). Fine radiating striation from 1.2–4 mm valve length. No or rudimentary dorsal median ridge or septum: ........................................................................................................................................................... 5

5a Adults uniplicate and dark-coloured. Lateral commissure unevenly curved. Ventral umbo rather long. Weak internal dorsal ridge (lacking in juveniles). Width of interspace much wider than striae on shell surface. Pedicle opening V- to U-shaped: ..................................................................................... Hemithiris psittacea ( Gmelin, 1791)

5b Rectimarginate anterior and straight lateral commissure. Shell brownish. Ventral umbo rather short. Short dorsal median septum or ridge. Very fine and dense striation. Pedicle opening typically partly enclosed by deltidial plates: ........................................... Hispanirhynchia cornea (Fischer, in Davidson 1887)

6a Up to 1.5 mm long, but usually less than 1 mm. Subcircular to elongate oval with small umbo and subequal valves. Rather inflated and lacking ornament. Pedicle opening large and partly extending into dorsal valve. Narrow but straight hinge line: ........................................................................................... Gwynia capsula ( Jeffreys, 1859)

6b Different ........................................................................................................................................................................................... 7

7a Pedicle opening large and partly extending into dorsal valve. Hinge line straight: ..................................................................................................................................... 8

7b Pedicle opening restricted to ventral valve, or only very slightly notching dorsal valve. Dorsal umbo not raised above curved to nearly straight hinge line: ....................................................................................................................................................... 14

8a Pedicle opening stretching far into the dorsal valve, typically forming a full half-circle on the upper surface. No radiate ornament. Dorsal umbo not raised above the hinge line. Short brachial loop: .............................................................................................................................................................................. 9

8b Pedicle opening not forming a half-circular hole on the upper surface of the dorsal valve, or, if so, then with some type of radiate ornament on ventral valve. Dorsal umbo usually slightly raised above the hinge line: ..................................................................................................................................................... 10

9a Only growth lines. Brachidial loop (=skeletal support of lophophore) with upper transverse band creating a triangular ring. Long setae (about 2/3 valve length) along valve margin. Subrectangular to transverse suboval: ................................................................................................................. Annuloplatidia annulata ( Atkins, 1959)

9b Only growth lines or with tuberculate ventral surface. No triangular brachial loop. Very short setae along valve margin. Subcircular to transverse suboval: .............................................................................. Platidia anomioides (Scacchi & Philippi, in Philippi, 1844)

10a Both valves with coarse costellate ribs lacking tubercles: ........................................................................................................................................................... 11

10b Ornament of only growth lines, or with tubercles/spines and/or fine costellae: ....................................................................................................................................... 12

11a 8–16 coarse ribs. Up to 3 mm long. Brachial loop anteriorly just attached to median septum. Typically whitish with red between ribs: ................................................................................................................... Argyrotheca cuneata ( Risso, 1826)

11b 7–18 broad ribs. Up to 6 mm long. Brachial loop attached to three to five septa including median septum. Light honeycoloured: ........................................................................... Megathiris detruncata ( Gmelin, 1791)

12a At least ventral valve with ribs. Long brachial loop. Rectimarginate to unisulcate .................................................................... 13

12b Ornamentation only composed of growth lines on both valves. Shell minute ( 3 mm) with median furrow in both valves (may be weak). Median septum in both valves: ........................................................................................... Argyrotheca cistellula ( Forbes & Hanley, 1849)

13a Both valves with dense, fine and tuberculate radiate ribs, though ventral valve usually has the stronger ornamentation. Shell biconvex and usually not markedly deformed from substrate ........................................................ Megerlia truncata ( Linnaeus, 1767)

13b Ventral valve with radiate ribs as well as low tubercles and often minute alveolar spines or thorns scattered on surface. No or extremely weak and scattered radiating ribs on dorsal valve. Shell usually moulted after substrate, with nearly plane or even concave dorsal valve: ................................................ Megerlia echinata ( Fischer & OEhlert, 1890)

14a Radiating ribs (may be absent on shells less than 1 mm long ...................................................................................................... 15

14b Faint striation or no ornamentation except growth lines. Shell longer than wide ........................................................................ 18

15a Ventral valve with interarea (yellow-marked plane triangular area bisected by pedicle opening). Nearly straight hinge line. Valve margins thickened and crenulate. Crura not extended to form a loop (red): ................................................................................................................................................... 16

15b No interarea. Curved hinge line. Brachial loop (red). Valve margin not thickened and crenulate. Generally do not identify specimens less than 1.5 mm long to species level for the following: ........................................................................................................................................................... 17

16a Up to about 44 beaded and rounded ribs distally. Middle dorsal rib and corresponding ventral interspace larger than other ribs. 5 mm long: ............................................................................................................................ Eucalathis tuberata ( Jeffreys, 1878)

16b Ornament of concentric bands and distally up to approximately 27 triangular ribs. Middle dorsal rib and corresponding ventral interspace not larger than other ribs. 7 mm long: .................................................................................................... Eucalathis ergastica Fischer & OEhlert, 1890

17a Umbonal ribs on ventral valve of juvenile specimens normally separated by deep interspaces and consisting of tubercles, of which some along the shell crest are slightly overhanging rib interspaces. 9–14 (rarely 17) rather coarse ribs per 5 mm counted 10 mm anterior of ventral umbo. Generally pentagonal outline:............................................................ Terebratulina retusa ( Linnaeus, 1758)

17b Tubercles lacking to dense, low and more like growth ridges on umbonal crest, and never overhanging interspaces. Stronger tubercles may occur laterally on umbo. 14–22 fine ribs per 5 mm counted 10 mm anterior of ventral umbo. Generally egg-shaped outline: .......................................................................... Terebratulina septentrionalis ( Couthouy, 1838)

18a Some form of dorsal median septum or ridge present (visible as a line or point on the outside of wet shells): ................................................................................................................................................................................ 19

18b Dorsal median septum absent ........................................................................................................................................................ 26

19a Short dorsal pillar-like median septum (seen as a dot on wet shells) in shells between 2 and 6 mm in length. Umbo blunted and with moderately large pedicle opening. Rudimentary deltidial plates rectangular, never meeting and sharply defined by ridges: ............................................................................................................................................... 20

19b Dorsal median septum/ridge seen as a knife cut-formed scar on the outer side of shells larger than 2 mm long (can be dot-shaped or absent in smaller specimens) ......................................................................................................................................... 21

20a Shell outline highly variable, from evenly rounded and very broad egg-shaped to nearly subpentagonal, elongate egg-shaped. Ventral umbo moderately developed. Moderately broad and broadly curved brachial loop (red): ................................................................................................ Macandrevia cranium ( Müller, 1776)

20b Shell outline usually elongate egg-shaped with poorly developed umbo and typically slightly truncated anterior margin. Fragile. Narrow loop with nearly subparallel sides (red): .................................................................................................... Macandrevia tenera ( Jeffreys, 1876a)

21a Short and poorly developed dorsal median ridge at umbo (~1/3 valve length): ..................................................................................................................................................................................... 22

21b Long dorsal median septum or ridge (dot-shaped basis in specimens less than 2 mm long ....................................................... 23

22a Shell 10 mm long. Egg-shaped outline with clearly visible deltidial plates in dorsal view (red). Vascula media of mantle canal system faintly showing or invisible: ....................................................................................................................................... Xenobrochus islandicus n. sp.

22b Shell 40 mm long. Typically with subpentagonal outline, and with short ventral umbo curved strongly in the dorsal direction, partly hiding the short deltidial plates (red). Imprints of vascula media of mantle canal system usually clearly visible on valve exterior as two straight, diverging, whitish lines on both dorsal and ventral valves (yellow): ....................................................................................................................................... Gryphus vitreus ( Born, 1778)

23a Ventral umbo beak-shaped and curved in specimens> 3.5 mm long. Pedicle opening egg-shaped. Teeth supported by dental plates (white arrow). Hinge plates not extended forward but connected to dorsal median septum at nearly right angles (yellow). Brachial loop always connected to median septum. Long pedicle collar (violet arrow): ..................................................................................... 24

23b Ventral umbo blunt. No dental plates supporting teeth. Hinge plates extended forward to connect to dorsal median septum in a distinct V-shape (yellow). Brachial loop not connected to dorsal median septum on specimens larger than 13 mm. No or few spicules in soft tissue. Pedicle foramen subcircular or circular in adults (but deltidial plates disjunct in juveniles below 6 mm in length). Short pedicle collar (turquoise): ......................................................................................... 25

24a Shell outline egg-shaped. Rectimarginate. Pedicle opening very elongate egg-shaped. 13 mm long: .............................................................................................................. Glaciarcula spitzbergensis ( Davidson, 1852c)

24b Shell rather broad and truncated even at 7 mm in length. Abundant spicules in soft tissue. Pedicle opening is shorter egg-shaped and typically extends well up on the ventral side of umbo. 25 mm long: ........................................................................................................................... Fallax dalliniformis Atkins, 1960a

25a 45 mm long. Typically rounded pentagonal but can be subtriangular. Subtriangular to egg-shaped as juvenile. Usually only weakly truncate before reaching 20 mm in length (red line: growth stage). Lateral commissure usually straight to gently curved. Shell moderately robust: ....................................................................................... Dallina septigera ( Lovén, 1846)

25b 30 mm long. Adult shell subtriangular to strongly triangular with greatest width usually at anterolateral corners. Lateral commissure usually moderately curved. Relatively fragile shell: ................................................................................................. Dallina lusitanica n. sp.

26a Shell whitish. Pedicle collar rather thick (green). Deltidial plates may be joined (red). Short loop (yellow). No dental plates supporting ventral hinge teeth: .................................................................................. 27

26b Pedicle collar rudimentary or absent (green). Deltidial plates never joined (red). Relatively long brachial loop (red): ................................................................................................................................ 28

27a Broad egg-shaped to pentagonal outline. Low deltidial plates mostly not joined and partly hidden in the dorsal view due to curved beak (red). Stubby or no rootlets on pedicle. Shell surface typically dull: ................................................................................................... Arctosia arctica ( Friele, 1877a)

27b Mostly elongate egg-shaped outline with dorsally clearly visible high and always joined deltidial plates (red). Distinct multiple rootlets on pedicle. Shell surface typically shiny and smooth: .......................................................................................................... Xenobrochus islandicus n. sp.

28a Shell whitish. Less than 1.65 mm long. Deltidial plates not bordered by distinct ridges (at arrow). No dental plates supporting ventral hinge teeth: ................................................................................................................... Juvenile Dallina septigera ( Lovén, 1846)

28b Shell of live specimens pale brownish (but empty shells become whitish). Deltidial plates of especially juvenile specimens bordered by ridges (arrow). Ventral hinge teeth supported by dental plates (arrows): ...................................................................................................................................... 29

29a Shell outline very variable, from evenly rounded and very broad egg-shaped to nearly subpentagonal elongate egg-shaped. 31 mm long. Ventral umbo comparatively large. Moderately broad and broadly curved brachial loop (red): ................................................................................................ Macandrevia cranium ( Müller, 1776)

29b Shell outline elongate egg-shaped with poorly developed umbo, with typically slightly truncated anterior margin. 13 mm long. Narrow loop with nearly subparallel sides (red):.................................................................................................. Macandrevia tenera ( Jeffreys, 1876a)