Recent thecideide brachiopods from the northern ...

Zoosyst. Evol. 85 (2) 2009, 341 –349 / DOI 10.1002/zoos.200900010

Recent thecideide brachiopods from the northern Great Barrier Reef, Australia (SW Pacific Ocean) Jana Hoffmann*, 1, Marleen Klann2 and Franziska Matz1 1 2

Museum fr Naturkunde, Invalidenstr. 43, 10115 Berlin, Germany Humboldt-Universitt zu Berlin, Insitut fr Biologie, Vergleichende Zoologie, Philippstr. 13, 10115 Berlin, Germany

Abstract Received 9 April 2009 Accepted 25 May 2009 Published 24 September 2009

Key Words Brachiopoda biodiversity Ospreyella Thecidellina insolita n. sp.

Species diversity of Recent thecidellinine brachiopods in the Pacific was long believed to be low, as only three species have been described so far. Newly available material from Lizard Island and Yonge Reef in the northern Great Barrier Reef, Coral Sea, SW Pacific was investigated by scanning electron microscopy and revealed a new thecidellinine species, Thecidellina insolita n. sp. In addition a brief description of another thecidellinine, Thecidellina sp., and one lacazelline species, Ospreyella sp., is provided. The descriptions offered here are the first record of Recent thecideide brachiopods from Lizard Island and its surroundings, though not from the Great Barrier Reef as a whole. This study documents the case that not only representatives of different lacazelline and thecidellinine genera, but also congeneric species co-occur in the same region. Moreover comparison with taxonomic descriptions provided for the genus Thecidellina from the West Pacific as a whole suggests that thecidellinine species diversity is highly underestimated and Thecidellina maxilla, a widespread species in the West Pacific, is more likely to represent a species-complex.

Introduction Recent thecideide brachiopods are marine sessile filter feeders inhabiting cryptic habitats on hard substrates such as those found in coral reefs or volcanic islands. In the West Pacific Ocean they are represented by three thecidellinine species, Thecidellina congregata Cooper, 1954, Thecidellina maxilla (Hedley, 1899), Thecidellina japonica (Hayasaka, 1938), and by three lacazelline species, Ospreyella depressa Lter, 2003, Ospreyella palauensis Logan, 2008 and Kakanuiella chathamensis Lter, 2005. Intensive morphological investigations of the genus Thecidellina from the Atlantic Ocean using scanning electron microscopy have elucidated a set of more reliable morphological characters for species discrimination. Based on this, an unexpectedly high species diversity within the Caribbean Sea was discovered (Lter et al. 2008; Hoffmann & Lter 2009). Conceivably, there is a comparable situation in the West Pacific Ocean. SEM investigations of newly available material

* Corresponding author, e-mail: [email protected]

# 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

from Lizard Island and Yonge Reef, both located in the Coral Sea, revealed a new species, Thecidellina insolita n. sp., described here, and two more, so far unidentified species, Thecidellina sp. and Ospreyella sp. Additionally, specimens of Thecidellina insolita n. sp. with well preserved soft tissue were investigated by SEM. This revealed new insights into thecidellinine soft body morphology and further complementary data on their reproductive and brooding habits.

Material and methods The investigated material originates from two different sources and several localities around Lizard Island and Yonge Reef, Coral Sea (for details see Tab. 1, Fig. 1). The material is deposited in Museum fr Naturkunde Berlin, Germany with specimens assigned numbers under the acronym “ZMB Bra”. It was collected by J. Reitner by SCUBA-diving between 1992–1993, previously fixed in glutaraldehyde and then transferred into 98 % ethanol. Another part of the material was collected by G. Wrheide by SCUBA-diving in 2006 and fixed in 98 % ethanol. To investigate shell morphology specimens

342

Hoffmann, J. et al.: Recent brachiopods from the Great Barrier Reef

Table 1. List of investigated material. * – total number of specimens (complete specimens; dorsal valves; ventral valves). Museum

Species

Locality

Coordinates

Numbers ZMB Bra 2103

Depth

Collector

Date

Thecidellina insolita n. sp.

Half Mile

14 340 2800 S

Opening,

145 360 8400 E

7 – 12

Numbers of specimens*

[m] J. Reitner

4 March 1993

SEM 1 (0; 1; 1) holotype

Yonge Reef ZMB Bra 2104


Half Mile

14 340 2800 S

Opening,

145 360 8400 E

7 – 12

J. Reitner

4 March 1993

10 (0; 6; 4) paratypes

Yonge Reef ZMB Bra 2105


Half Mile

14 340 2800 S

Opening,

145 360 8400 E

5

J. Reitner

11 March 1993

8 (2; 3; 3) [SEM 5 (0; 4; 1)]

Yonge Reef ZMB Bra 2106 ZMB Bra 2107 ZMB Bra 2108

Thecidellina insolita n. sp. Thecidellina insolita n. sp. Thecidellina insolita n. sp.

Lizard Island,

14 420 S

South Island

145 270 E

Lizard Island,

14 420 S

South Island

145 270 E

Lizard Island,

14 420 S

South Island,

145 270 E

8.5

J. Reitner

20 May 1992

20 (0; 11; 10) [SEM 9 (0; 4; 6)]

8

J. Reitner

20 May 1992

5 (0; 4; 2) [SEM 2 (0; 2; 1)]

4–5

J. Reitner

9 March 1993

10

J. Reitner

18 April 1992

1 (0; 1; 0)

Research Cave ZMB Bra 2109


Lizard Island,

14 380 S

Washing

145 270 E

1 (0; 1; 1) [SEM 1 (0; 1; 0)]

Machine, cave ZMB Bra 2110


Lizard Island,

14 390 S

Bommie Bay

145 280 E

6

J. Reitner

8 March 1993

–

G. Wo¨ rheide

February 2006

1 (0; 1; 1)

Research Cave ZMB Bra 2111 ZMB Bra 2118 ZMB Bra 2112 ZMB Bra 2113

Thecidellina insolita n. sp. Thecidellina sp. Ospreyella sp. Ospreyella sp.

Lizard Island,

14 380 4200 S

North Point

145 270 1200 E

Lizard Island,

14 380 4200 S

North Point

145 270 1200 E

Lizard Island,

14 420 S

South Island

145 270 E

Lizard Island,

14 390 S

Bommie Bay

145 280 E

9 (3; 6; 6) [SEM 4 (0; 4; 4)]

–

G. Wo¨ rheide

February 2006

8

J. Reitner

20 May 1992

SEM 1 (0; 1; 1) 3 (0; 3; 3) [SEM 2 (0; 2; 2)]

6

J. Reitner

8 March 1993

SEM 1 (0; 1; 1)

Research Cave ZMB Bra 2119

Ospreyella sp.

Lizard Island

–

10

J. Reitner

4 April 1992

1 (1; 0; 0)

ZMB Bra 2120

Ospreyella sp.

Lizard Island,

14 420 S

8.5

J. Reitner

20 May 1992

1 (1; 0; 0)

South Island

145 270 E

were bleached with 3 % sodium hypochlorite, subsequently rinsed in tap water and air-dried. A subset of valves with residues of soft-tissue was treated with HMDS (see Nation 1993), mounted, sputter-coated with gold/palladium in a Polaron SC 7640 Sputter Coater and examined in a LEO VP 1450 and JEOL JSM-6300 scanning electron microscope. The Leica Application Suite v2.8.1, a zoom system (Leica Z16 APO A zoom macroscope, Leica DFC 490 digital camera) and AutoMontage Essentials v5.03 generated extended depth field images of bleached valves and valves with soft-tissue. Measurements were taken with ImageJ 1.37v using the extended depth images and SEM pictures. Digital images were edited and finally arranged as photographic panels using Adobe Photoshop1 CS2 and Adobe Illustrator1 CS2. Digital drawings were created with Adobe Illustrator1 CS2 and Adobe Photoshop1 CS2 (Coleman 2003). DELTA v1.04 (DEscription Language for TAxonomy) was used for generating the taxonomic descriptions.

Results Order Thecideida Elliott, 1958 Superfamily Thecideoidea Gray, 1840 Family Thecidellinidae Elliott, 1958 Subfamily Thecidellininae Elliott, 1953 Genus Thecidellina Thomson, 1915 Thecidellina insolita n. sp. Figure 2–3 Type material. Holotype ZMB Bra 2103 (one specimen, separated valves, bleached and dried, SEM preparation); paratypes ZMB Bra 2104 (10 specimens; 9 specimens: dry; one specimen: ethanol). Type locality. Half Mile Opening, Yonge Reef, Great Barrier Reef, Australia, Coral Sea, Western Pacific Ocean, coordinates: 14 340 2800 S 145 360 8400 E, water depth: 7–12 m, collected by Joachim Reitner, 4 May 1993.

museum-zoosyst.evol.wiley-vch.de


Zoosyst. Evol. 85 (2) 2009, 341 –349

343

calcitic pole not entirely fused to floor of cardinal process, cone-like; visceral foramen only partially divided by calcitic pole; lateral adductor muscle scars extending beyond insertion of cardinal process; brachial bridge broad with well-defined lophophore muscle scars, ovarial notches absent; visceral gap unclosed; median septum broad, anteriorly slightly diverging, concavoconvex; marsupial orifices well-defined, large; brachial cavity uncovered or partly covered by single mass of canopying spicules; body wall with additional perforations.

Figure 1. Map of Lizard Island and Yonge Reef with symbols representing the collecting sites of Thecidellina insolita n. sp. (filled circle), Thecidellina sp. (open circle) and Ospreyella sp. (stars).

Etymology. The species name is derived from Latin “insolitus” meaning unusual or rare and refers to the unexpected combination of morphological characters of this new-described thecidellinine species. Additional material. ZMB Bra 2105 Yonge Reef; ZMB Bra 2106–2108 South Island, Lizard Island; ZMB Bra 2109–2111 Lizard Island. Distribution. Lizard Island, Yonge Reef, Great Barrier Reef, Western Pacific Ocean. Diagnosis. Ventral valve pseudodeltidium absent; gonad pits forming deep depressions on either side of hemispondylium. Dorsal valve profile posteriorly ascending;

Description of shell. Average-sized thecideide brachiopod, maximum length 4.09 mm (see Tab. 2). Shell longer than wide, biconvex, rectimarginate. Ventral valve sparsely punctate (Fig. 2b). Interarea flat, triangular with well-defined parallel growth lines; angle 86.25 (n ¼ 19; Tab. 2); pseudodeltidium absent (Figs 2b, e). Ventral valve floor sculptured, with irregular calcitic papillae (Fig. 2b). Median ridge absent. Gonad pits present, laterally of hemispondylium, forming deep depressions, restricted to posterior part of valve, elongated, without canopying tubercles (Fig. 2b). Teeth surface covered with tongue-like secondary shell fibres. Hemispondylium lifted from valve floor or fused to valve floor, without supporting septum; prongs apically pointed, medially fused, forming distinct calcitic platform for muscle attachment or fused with ventral valve floor (Figs 2b, k). Peripheral margin narrow, with round crater-like tubercles (Figs 2b, j). Dorsal valve about as wide as long, sparsely punctate (Fig. 2a); punctae large; profile posteriorly ascending (Fig. 2c). Cardinal process prominent, extending far beyond hinge margin, trilobate, median lobe well-defined (Figs 2a, h); lateral lobes covered with long fibres of secondary shell material, outer margins with longitudinal ridges (Figs 2h); diductor muscle scars well-defined on posterior-most margin, fin-shaped, separated by median elevation (Fig. 2h). Lateral adductor muscle scars reniform, extending beyond insertion of cardinal process (Figs 2d, g). Median adductor muscle scars located in visceral cavity, planar (Figs 2f, i). Calcitic pole present, not entirely fused with cardinal floor (Figs 2d, f, g), cone-like, slender (Figs 2d, g); surface smooth. Visceral foramen partially divided by calcitic pole. Brachial bridge broad; surface smooth; inner margin with well-defined parallel lophophore muscle scars (Figs 2a, i, l); ovarial notches absent (Fig. 2g); marsupial notch

Table 2. Measurements of dorsal and ventral valve of Thecidellina insolita n. sp. DV – dorsal valve; VV – ventral valve; L – length; W – width. DV L [mm] Size range Mean SD Specimens

VV W [mm]

L [mm]

W [mm]

angle [ ]

1.73 –2.79

1.75 – 3.37

2.02 – 4.09

1.56 – 3.68

74.9 –106.9

(2.17 0.21)

(2.25 0.31)

(2.46 0.51)

(2.12 0.45)

(86.25 9.33)

n ¼ 30

n ¼ 30

n ¼ 24

n ¼ 26

n ¼ 19



344


Figure 2. Thecidellina insolita n. sp. a. Dorsal valve, habitus (= entire shell), median septum concavoconvex, posteriorly with median crest (arrowhead), holotype, ZMB Bra 2103; b. Ventral valve, habitus, holotype, ZMB Bra 2103; c. Dorsal valve, lateral view, holotype, ZMB Bra 2103; d. Dorsal valve, posterior view, holotype, ZMB Bra 2103; e. Ventral valve, interarea with parallel growth lines, ZMB Bra 2105; f. Dorsal valve, latero-posterior view of cardinal region with missing connection of calcitic pole and cardinal floor (arrowhead) and imprints of median adductor muscles (mas), holotype, ZMB Bra 2103; g. Dorsal valve, posterior view, gap (arrowhead) between cardinal floor and calcitic pole (p), visceral gap (vg) large and unclosed, lateral adductor muscle scars (las) on either side of cardinal process, holotype, ZMB Bra 2103; h. Dorsal valve, cardinal process with prominent longitudinal ridges (lr) on each lateral lobe and well-defined didcutor muscle scar (dms), ZMB Bra 2111; i. Dorsal valve, median adductor muscle scars (mas) well-defined, body wall with large marsupial orifices (mo) on either side of the median septum and additional randomly distributed perforations (arrowheads), ZMB Bra 2105; j. Ventral valve, crater-like tubercles (t) on peripheral rim, ZMB Bra 2105; k. Ventral valve, angled view of interarea, teeth and hemispondylium with two distally pointed prongs (pro), ZMB Bra 2106; l. Dorsal valve, brachial bridge with welldefined lophophore muscle scars (lms), ZMB Bra 2105; m. Dorsal valve, brachial lobes with single massive canopying spicules (cs), ZMB Bra 2106. Scale bars: a ¼ 1 mm; b ¼ 2 mm; c–d ¼ 500 mm; e ¼ 400 mm; f–g, j–k ¼ 200 mm; h–i, m ¼ 300 mm; l ¼ 100 mm.



Zoosyst. Evol. 85 (2) 2009, 341 –349

absent (Figs 2f, i). Visceral gap unclosed (Figs 2a, g, i). Median septum undivided, broad, slightly diverging anteriorly (Fig. 2a); crest with median ridge, concavoconvex (Figs 2a, c). Marsupial orifices well-defined (Figs 2a, i), large. Brachial cavity present, uncovered or partly covered by canopying spicules; canopying spicules single and slender (Figs 2a, m). Lophophore schizolophous. (Inter)brachial lobes margin dentate (Fig. 2a). Intrabrachial ridges forming body wall with unusual additional perforations (Figs 2a, i). Subperipheral rim tubercles discrete and roundish (Figs 2a, c);

345

anterior margin regular. Dental sockets without ridges (Fig. 2g). Description of soft body parts. The anteriorly directed tentacles of the schizolophous lophophore are densely packed and unequal in length with the outer posteriormost tentacles the longest (Fig. 3a). The individual tentacle exhibits two lateral bands of cilia (Fig. 3g). In between the tentacles a single calcitic formation emerges, originating from the margins of the interbrachial lobes (Fig. 3a). The distal tips of the tentacles are curled.

Figure 3. Thecidellina insolita n. sp. a. Dorsal valve, schizolophous lophophore (l) and calcitic projections between single lophophore tentacles (arrowheads), residues of lateral adductor muscles present (la), ZMB Bra 2105; b. Dorsal valve, habitus, lophophore removed, brood pouches with one single larva, ZMB Bra 2111; c. Dorsal valve, lateral adductor muscle scar with imprints of individual muscle fibres (arrowheads), holotype, ZMB Bra 2103; d. Dorsal valve, posterior view, with preserved lateral adductor muscles (la), median adductor muscles (ma) and diductor muscles (di), ZMB Bra 2105; e. male gonad, paratype, ZMB Bra 2104; f. Dorsal valve, posterior margin of cardinal process, median lobe, diductor muscles with two attachment sites divided by a median crest (arrowhead), ZMB Bra 2105; g. Dorsal valve, single lophophore tentacle with lateral band of cilia (arrowhead), cilia still present or removed, leaving small insertion marks, ZMB Bra 2105; h. Male gonad, surface covered with single mature spermatozoa, paratype, ZMB Bra 2104. Scale bars: a ¼ 1 mm; b ¼ 500 mm; c ¼ 40 mm; d ¼ 400 mm; e–f ¼ 100 mm; g ¼ 30 mm; h ¼ 10 mm.



346

The female has two separated brood pouches located in each of the brachial cavities (Fig. 3b). They are partly covered by flanking massive canopying spicules. One of the brood pouches contains one early lecitotrophic larva (diameter ¼ 226 mm). The brood pouches are formed by mantle tissue and taper posteriorly towards the marsupial orifices. Tentacles do not penetrate the brood pouches. The muscle bundles are formed by single muscle fibres, which are attached individually to characteristic shell regions in the dorsal and ventral valve. They leave characteristic muscle scars, when removed (Fig. 3c). The median adductor muscles are represented by two separate bundles of muscle fibres, leaving two characteristic muscle scars on the floor of the visceral cavity of the dorsal valve. They unite underneath the brachial bridge (Fig. 3d) and are attached to the floor of the hemispondylium of the ventral valve. The diductor muscles are clearly separated into two bundles and attached to the posterior-most margin of the cardinal process (Figs 3d, f). A narrow crest separates the two individual attachment sites (Fig. 3f). The lateral adductor muscles are represented by two separated bundles of muscles on either side of the cardinal process (Figs 3a, d). They are the most prominent muscles of thecideide brachiopods. The only preserved gonads originate from a male specimen (length ¼ 531 mm, width ¼ 211 mm). The male gonads are elongated and form a massive body (Fig. 3e). They are located in the gonad pits on either side of the hemispondylium. Single mature spermatozoa are entirely covering the gonads’ surface (Figs 3e, h). Remarks. Sympatric with Thecidellina sp., Ospreyella sp.

Thecidellina sp. Figure 4 Material. ZMB Bra 2118 – Lizard Island, North Point (one specimen, separated valves, dry, SEM preparation). Description. Average-sized thecideide brachiopod, maximum length observed 3.42 mm. Shell wider than long, almost flat. Ventral valve densely punctate (Fig. 4b). Interarea flat, triangular with well-defined parallel growth lines (Fig. 4b); angle 104.4 (n ¼ 1); pseudodeltidium absent. Ventral valve floor granulose. Median ridge absent. Gonad pits present, laterally of hemispondylium, almost planar, reaching half of valve length, elongated, without canopying tubercles (Fig. 4b). Hemispondylium fused to valve floor. Dorsal valve wider than long, densely punctate (Fig. 4a); punctae large (Fig. 4a); profile relatively flat (Fig. 4c). Cardinal process median lobe well-defined; diductor muscle scars well-defined on posterior-most margin, fin-shaped (Fig. 4a). Lateral adductor muscle



scars reniform, extending beyond insertion of cardinal process (Fig. 4d). Calcitic pole present, completely fused with cardinal floor, pillar-like, massive; surface smooth (Fig. 4d). Visceral foramen completely divided by calcitic pole (Fig. 4d). Brachial bridge slender; inner margin lophophore muscle scars faint (Fig. 4a); ovarial notches well-defined (Fig. 4a). Visceral gap partly closed with shell material. Lateral holes present, on either side of mouth opening, small, slit-like (Fig. 4d). Median septum broad, heavily diverging anteriorly (Fig. 4a); crest smooth, slightly concavoconvex. Marsupial orifices minute. Brachial cavity present, uncovered. Lophophore schizolophous. (Inter)brachial lobes margin dentate. Remarks. This specimen belongs to a Thecidellina species other than T. insolita n. sp. Unfortunately only this single individual was found, therefore a species description seems inappropriate at this stage. Thecidellina sp. is found sympatric with Thecidellina insolita and Ospreyella sp.

Subfamily Lacazellinae Backhaus, 1959 Genus Ospreyella Lter & Wrheide, 2003 Ospreyella sp. Figure 4 Material. ZMB Bra 2112 – South Island, Lizard Island (3 specimens: 2 specimens, bleached and dried, SEM preparation); ZMB Bra 2113 – Bommie Bay, Lizard Island (one specimen, bleached and dried, SEM preparation); ZMB Bra 2119 – Lizard Island (one specimen); ZMB Bra 2120 – South Island, Lizard Island (one specimen). Description. Maximum length observed 2.60 mm. Ventral valve sparsely punctate. Interarea flat, triangular with well-defined parallel growth lines; angle 84.5 (n ¼ 1); pseudodeltidium present (Fig. 4f). Ventral valve floor smooth. Gonad pits vestigial. Surface of teeth with tubercle-like protuberances topped with secondary shell material (Fig. 4h). Hemispondylium lifted from valve floor, without supporting septum (Fig. 4h); prongs plate-like, medially fused, forming myophragma (Figs 4f, h). Peripheral margin anteriorly ill-defined, narrow, with elongated ridge-like tubercles. Dorsal valve wider than long, sparsely punctate (Fig. 4e); punctae large; profile posteriorly ascending. Cardinal process prominent, extending far beyond hinge margin, trilobate, median lobe anteriorly subdued (Figs 4e, g); outer margins without longitudinal ridges; diductor muscle scars vestigial. Lateral adductor muscle scars reniform, extending beyond insertion of cardinal process (Fig. 4g). Median adductor muscle scars located in visceral cavity, planar. Calcitic pole absent. Visceral foramen undivided. Brachial bridge slender; inner mar-


Zoosyst. Evol. 85 (2) 2009, 341 –349

347

Figure 4. Thecidellina sp., ZMB Bra 2118 a. Dorsal valve, habitus, ovarial notches (on) well-defined, median septum (ms) very broad with large punctae; b. Ventral valve, habitus, small interarea (ia) without pseudodeltidium, gonad pits (gp) well-defined; c. Dorsal valve, lateral view; d. Dorsal valve, posterior view with slit-like lateral holes (lh) and massive calcitic pole (p) fused to cardinal floor. Ospreyella sp. e. Dorsal valve, habitus with two minor interbrachial lobes and well-defined median anterior depression (arrowhead), ZMB Bra 2112; f. Ventral valve, habitus with pseudodeltidium (pd), ZMB Bra 2113; g. Dorsal valve, posterior view, ZMB Bra 2112; h. Ventral valve, hemispondylium with myophragma (arrowhead) and two plate-like prongs (pro), ZMB Bra 2112; i. Dorsal valve, margin of intrabrachial ridges heavily serrate with two prominent spines on either side of median septum (arrowhead), ZMB Bra 2112; j. Dorsal valve, habitus, juvenile stage with undeveloped minor interbrachial lobes (empty arrowhead) but well-defined marsupial notch (mn), intrabrachial ridges with prominent spines (arrowhead), ZMB Bra 2113. Scale bars: a–e, g ¼ 500 mm; f ¼ 300 mm; i–j ¼ 200 mm; h ¼ 100 mm.

gin with well-defined parallel lophophore muscle scars, surface smooth (Fig. 4e); marsupial notch present in females (Fig. 4j). Visceral gap unclosed. Median septum bifurcate (Fig. 4j). Brachial cavity absent. Lophophore ptycholophous; two minor interbrachial lobes present, posteriorly connected to jugum (Fig. 4e), without further furcation; (inter)brachial lobes margin dentate,


frayed (Figs 4e, i). Intrabrachial ridges arch-like, leaving characteristic holes; margins heavily dentate with two prominent posteriorly directed spines (Figs 4i, j). Subperipheral rim tubercles discrete or aggregate, only posteriorly forming regular longitudinal ridges; anterior margin with median depression (Figs 4e, j).


348

Remarks. Unfortunately most of the few valves present were badly damaged and only three of them, probably juvenile specimens of Ospreyella sp., could be investigated. Hence a full species description or proper assignment to one of the known species, cannot be provided at present.

Discussion Taxonomy Thecidellina insolita n. sp. exhibits some previously undescribed morphological characters for the genus, e.g. the missing calcitic connections between the brachial bridge and the intrabrachial ridges and the unconnected calcitic pole underneath the brachial bridge. However, these are not the only characters, which separate it from all other Pacific species. T. japonica (Hayasaka, 1938) from Japan differs from T. insolita in the convex median septum in the dorsal valve and the prominent median ridges in the ventral valve. T. congregata Cooper, 1954 can be distinguished from T. insolita by its larger body size, the massive reticulated canopying spicules and the straight blade-like median septum with a median boss. T. maxilla (Hedley, 1899) seems to be the most closely related species to T. insolita in the Pacific, despite its unclear taxonomic status. Following the original description of Hedley (1899: p. 509, fig. 57) T. maxilla exhibits no calcitic connections between the bridge and the intrabrachial ridges and has well-defined marsupial orifices on either side of the median septum very similar to T. insolita. Apart from this T. maxilla is more than twice as large as specimens of T. insolita, has a minute cardinal process, an elongated dorsal valve, a slender median septum, densely punctate valves and the pole is completely fused to the cardinal valve floor. Among the material from Lizard Island one specimen of about the same size as T. insolita but with completely different morphological features was discovered. This individual shows the typical calcitic connection of the brachial bridge with the intrabrachial ridge, a massive calcitic pole connecting the bridge with the cardinal floor and very large punctae. It neither belongs to comparable stages of T. japonica (Haysaka 1938; Hoffmann & Lter in press: pl. 5, fig. 21), nor to T. congregata (Logan 2008: p. 410, fig. 6.16). Additionally, specimens of Ospreyella sp. were discovered in the material from Lizard Island, which do resemble juvenile stages of O. palauensis (Logan 2008: p. 410, figs 6.7–6.8) and are very unlike O. depressa (Lter 2003: p. 1427, fig. 2C), with which they would be biogeographically more closely associated. The hemispondylium of Ospreyella sp. lacks a supporting structure (= supporting septum), similar to O. palauensis, which clearly separates it from representatives of the genus Lacazella Munier-Chalmas, 1880, which always have that supporting structure.



Biogeography and biodiversity Taxonomic work carried out on Recent thecideides of the West Pacific Ocean suffers from a patchy distribution of available samples and the low number of workers specialized in this particular brachiopod group. A systematic approach of sampling and recording Pacific thecideide brachiopod species has not yet been carried out. A striking fact is that to date only three species of the genus Thecidellina have been described from the West Pacific Ocean, T. maxilla, T. japonica and T. congregata. Some of these species are supposed to have an extremely wide-ranging distribution throughout the West Pacific, e.g. T. congregata – Central West Pacific Ocean; Bikini Atoll / Marshall Islands (Cooper 1954), Eniwetok Atoll / Marshall Islands (Zumwalt 1976), Guam and Saipan (Thayer & Allmon 1990; Logan 2008) and T. maxilla – entire West Pacific Ocean; Funafuti Atoll / Tuvalu (Hedley 1899), Bikini Atoll / Marshall Islands (Cooper 1954), Torres Strait and Vanuatu (Thomson 1927), Gambier, Tuamotu / French Polynesia (Pajaud 1970), whereas others are known to be restricted to a very small geographic region, e.g. T. japonica from Japan (Hayasaka 1938). Furthermore Cooper (1954) described T. maxilla and T. congregata as overlapping in their biogeographical distribution, at least in the region of the Bikini Atoll, and thus occurring here sympatrically. By contrast Lee & Robinson (2003) suggested that all Indo-Pacific forms were variants of T. maxilla, a supposition recently supported by specimens described as T. maxilla from the Kermadec Islands (Lee & Robinson 2003) and French Polynesia (Bitner 2007). However, the presumed low number of Thecidellinaspecies in the West Pacific compared to the large geographic distances between the populations seems to contradict their expected low dispersal ability (James et al. 1992; Richardson 1997) and the high species diversity of Thecidellina observed in the Caribbean Sea / Atlantic Ocean. Here at least four species have been recorded within comparatively small geographical distances (Davidson 1864; Lter et al. 2008; Hoffmann & Lter 2009). Furthermore, illustrations of T. maxilla originating from other places than the type locality, e.g. Kermadec Island (Lee & Robinson 2003: p. 351, figs 28, 31) and French Polynesia (Bitner 2007: p. 497, figs D–F) reveal noticeable differences in shell morphology, e.g. the presence of the connection between the brachial bridge and the intrabrachial ridge, the size of the cardinal process and the convex profile of the median septum, when compared to the original description by Hedley (1899: p. 509, fig. 57). It is therefore likely that species diversity in the Pacific has been highly underestimated and T. maxilla may in fact represent a hitherto undiscovered species-complex. This hypothesis is corroborated by the description of the new species T. insolita from Lizard Island being closely related to T. maxilla from Tuvalu.


Zoosyst. Evol. 85 (2) 2009, 341 –349

Biology Thecideide brachiopods are known to be part of a characteristic brachiopod fauna living in cryptic habitats of Recent and past tropical and subtropical warm-water reefs, which is composed of megathyrids, craniids and thecideides (Cooper 1954; Jackson 1971; Lee & Robinson 2003). Densities of about 5000 specimens/m2 of Thecidellina (Jackson et al. 1971) have been recorded from the Pacific making them one of the most abundant brachiopods of these particular habitats (Jackson et al. 1971; Bitner 2007). Representatives of different thecideide genera are known to co-occur in the same area or on the same piece of substrate, e.g. in the Bahamas (Hoffmann & Lter in press). However abundances of representatives of the different genera usually vary greatly from habitat to habitat (Jackson et al. 1971). Interestingly, there is only one record of sympatry for species of the same genus, T. maxilla and T. congregata from Bikini Atoll (Cooper 1954). Remarkably, Lizard Island provides the first example for both cases: co-occurrence of representatives of different genera (Ospreyella and Thecidellina) and sympatry of congeneric species (Thecidellina insolita n. sp. and Thecidellina sp.). Brooding in Thecidellina has been described and documented for Thecidellina sp. from Osprey Reef / Pacific (Lter 2007) and T. meyeri Caribbean Sea / Atlantic (Hoffmann & Lter 2009). In Thecidellina insolita n. sp. one of the brood pouches contained only one single larva. Whether the number of larvae in the brood pouches depends on the individual shell size, maturity or is simply species-specific will need to be clarified in future investigations.

Acknowledgements The main practical work for this investigation was carried out within the framework of a master course for students of the Humboldt-University of Berlin held in the Museum fr Naturkunde Berlin in February 2009. Special thanks to J. Reitner and G. Wrheide for donating the specimens and providing helpful additional collection data. We would like to thank K. Born and P. Czaja for their technical assistance with processing the samples for SEM-investigations. Financial support by the Deutsche Forschungsgemeinschaft (project: PHYLOTEC LU 839/3) is gratefully acknowledged. We thank A. Logan, C. Lter and J. Dunlop for comments on a first draft of this paper.

References Bitner, M. A. 2007. Recent brachiopods from the Austral Islands, French Polynesia, South-Central Pacific. – Zoosystema 29: 491– 502. Coleman, C. O. 2003. “Digital inking”: How to make perfect line drawings on computers. – Organisms, Diversity and Evolution 3, Electronic Supplement 14: 1–14. http://senckenberg.de/odes/0314.htm14 Cooper, G. A. 1954. Recent brachiopods in Bikini and nearby atolls, Marshall Islands. – United States Geological Survey Professional Paper 260 G: 315–318.


349

Davidson, T. 1864. On the Recent and Tertiary species of Thecidium. – Geological Magazine 1: 12–22. Hayasaka, I. 1938. A new neotreme genus of Brachiopoda from Japan. – Venus 8: 9–13. Hedley, C. 1899. The mollusca of Funafuti. Part II. – Pelecypoda and Brachiopoda. – Memoirs of the Australian Museum 3: 491–510. Hoffmann, J. & Lter, C. 2009. Shell development, growth and sexual dimorphism in the Recent thecideide brachiopod Thecidellina meyeri sp. nov. from the Lesser Antilles, Caribbean. – Journal of the Marine Biological Association of the United Kingdom 89 (3): 469–479. Hoffmann, J. & Lter, C. in press. Shell development in thecidellinine brachiopods with description of a new genus. – Special Papers in Paleontology. Jackson, J. B. C., Goreau, F. & Hartman, W. D. 1971. Recent brachiopod-coralline sponge communities and their paleoecological significance. – Science 173: 623–625. James, M. A., Asell, A. D., Collins, M. J., Curry, G. B., Peck, L. S. & Rhodes, M. C. 1992. Biology of living brachiopods. – Advances in Marine Biology 28: 175–387. Lee, D. E. & Robinson, J. H. 2003. Kakanuiella (gen. nov.) and Thecidellina: Cenozoic and Recent thecideide brachiopods from New Zealand. – Journal of the Royal Society of New Zealand 33: 341–361. Logan, A. 2008. Holocene thecideide brachiopods from the northwestern Pacific Ocean: systematics, life habits and ontogeny. – Systematics and Biodiversity 6: 405–413. Lter, C. 2005. The first Recent species of the unusual brachiopod Kakanuiella (Thecideidae) from New Zealand deep waters. – Systematics and Biodiversity 3: 105–111. Lter, C. 2007. Anatomy. In Selden, P. A. (ed.). Treatise on Invertebrate Paleontology, part H: Brachiopoda, revised, Vol. 6, Supplement. The Geological Society of America and University of Kansas Press, Boulder and Lawrence: pp. 2321–2355. Lter, C., Hoffmann, J. & Logan, A. 2008 (for 2007). Cryptic speciation in the Recent thecideide brachiopod Thecidellina in the Atlantic and the Caribbean. – Transactions of the Royal Society of Edinburgh 98: 405–413. Lter, C., Wrheide, G. & Reitner, J. 2003. A new thecideid genus and species (Brachiopoda, Recent) from submarine caves of Osprey Reef (Queensland Plateau, Coral Sea, Australia). – Journal of Natural History 37: 1423–1432. Munier-Chalmas, M. 1880. Note sommaire sur les genre de la famille des Thecideidae. – Bulletin de la Socit gologique de France (srie 3) 8: 279–280. Nation, J. L. 1993. A new method using hexamethyldisilazane for preparation of soft insect tissues for scanning electron microscopy. – Stain Technology 58: 347–351. Pajaud, D. 1970. Monographie des Thcides (Brachiopodes). – Mmoires de la Socit Gologique de France (Nouvelle Srie) 112: 1–349. Richardson, J. R. 1997. Ecology of articulate brachiopods. In Kaesler, R. L. (ed.). Treatise on Invertebrate Paleontology, part H: Brachiopoda, revised, Vol. 1. The Geological Society of America and University of Kansas Press, Boulder and Lawrence: pp. 441–462. Thayer, C. W. & Allmon, R. A. 1990. Unpalatable thecideid brachiopods from Palau: Ecological and evolutionary implications. In MacKinnon, D. I., Lee, D. E. & Campbell, J. D. (eds). Brachiopods through time. Balkema, Rotterdam: pp. 253–260. Thomson, J. A. 1927. Brachiopod morphology and genera (Recent and Tertiary). New Zealand Board of Science and Art, Manual 7: 338 pp. Zumwalt, G. S. 1976. The functional morphology of the tropical brachiopod Thecidellina congregata Cooper, 1954. Unpublished MSc thesis, University of California, Davis, USA, 135 pp.
