Lenticellaria gregoryi Simon, Logan & Mottequin

Simon, Eric, Logan, Alan, Zuschin, Martin, Mainguy, Jerome & Mottequin, Bernard, 2016, Lenticellaria and Hillerella, new kraussinoid genera (Kraussinoidea, Brachiopoda) from Indo-Pacific and Red Sea waters: evolution in the subfamily Megerliinae, Zootaxa 4137 (1), pp. 1-34 : 14-20

Lenticellaria gregoryi Simon, Logan & Mottequin , sp. nov.

Pl. 6, Figs 1–4; Pl. 7, Figs. 1–3; Pl. 8, Figs. 1–2; Pl. 9, Figs. 1–2.

Holotype. Lenticellaria gregoryi Simon et al. , Pl.6, Figs. 3a–c; Pl. 8, Figs. 1a–g, 2a–f; Pl. 9, Figs. 1a–e. It is a perfectly preserved articulated specimen which has been opened for the present study and is preserved in the collections of the Royal Belgian Institute of Natural Sciences, RBINS-BT. 4. The morphological measurements of the holotype are indicated in Table 1 .

Paratypes. RBINS-BT. 5. A complete articulated specimen illustrated from Kodingareng, Makassar, Indonesia Pl. 6, Figs. 1a–b, 4a–g and Pl. 7, Fig. 1a–f. RBINS-BT. 6. A ventral valve from Kodingareng, Makassar, Indonesia illustrated Pl. 6, Fig. 2; Pl. 7, Fig. 2a–f. RBINS-BT. 8. A ventral valve from Tulamben, Bali, Indonesia illustrated Pl. 7, Fig. 3a–c. RBINS –BT. 7. Complete articulated juvenile specimen from Kodingareng, Makassar, Indonesia illustrated Pl. 9, Figs. 2a–g.

Etymology. This species is dedicated to the late Gregory Willems and his first name is used for the species name.

Locus typicus: Tanker-shipwreck near Kodingareng Island (Spermonde Archipelago), Makassar, South Sulawesi, Indonesia (5°06’17.43” S 119°17’03.92”E).

Material investigated

From Makassar (Kodingareng wreck): 15 specimens. 10 complete articulate specimens of different sizes (one was a living specimen, now preserved in ethanol), two isolated dorsal valves with brachidium and three isolated ventral valves.

From Tulamben (Bali): one articulated specimen, one ventral valve and three incomplete ventral valves.

Diagnosis of species. Micromorphic brachiopod, wider than long with a semicircular outline in dorsal view. The external surface of the dorsal valve is smooth whereas the external surface of the ventral valve has radial tuberculation. Between the radial rows of tubercles, numerous scales with typical “Gaussian curve” outline are developed in concentric lines. Foramen amphithyrid. Cardinal process and hinge plates absent. Inner dorsal valve floor tuberculate. Short crura developed. Loop, going through a cucullate phase, a “pseudo” annular phase and finally consisting of two simple claws, relatively wide, with sharp tips. Base of the bifid septum unraised. Descending branches absent. Septum on the ventral valve floor partly interrupted in its posterior portion.

Diagnose de l’espèce. Brachiopode micro-morphique, plus large que long avec un aspect semi-circulaire en vue dorsale. La surface extérieure de la valve dorsale est lisse tandis que la surface de la ventrale montre une ornementation radialement tuberculée. Entre les rangées de tubercules se développent des écailles distribuées en lignes concentriques. Foramen amphithyride. Processus cardinal et plaques de charnière absentes. Surface dorsale interne tuberculée. Crura très courtes toujours présentes. Brachidium adulte consistant en deux pinces à extrémités pointues formées par une phase cucculée évoluant par une « pseudo » phase annulaire. Branches descendantes absentes. Septum de la valve ventrale interrompu dans sa partie postérieure.

Mendiagnosia. « Micromorphic » Brachiopoda, lebih lebar dari panjang dengan bentuk setengah lingkaran kelau dilihat atas katup dorsal. Permukaan luar katup dorsal halus sedangkan permukaan luar katup ventral adalah baris radial dengan duri tebal. Antara baris radial dari tuberkel ada banyak skala yang berbentuk « kurva Gaussian » dikembangkan di garis konsentris. Foramen amphithyrid. Tidak ada kardinal proses. Tidak ada engsel piring. Dalam lantai katup punggung ada tuberkel juga. Krura singkat dikembangkan. Brachidium, akan melalui fase cucullate, sebuah "pseudo" berbentuk gelang fase dan akhirnya merupakan dua cakar, relativ luas, sederhana dengan teratas tajam. Septum mendua, masih sangat datar. Cabang turun tak pernah dikembangkan. Septum di lantai katup ventral sebagian terputus di bagian posteriornya.

Description. Micromorphic kraussinid brachiopod more or less semi-circular in dorsal outline, slightly wider than long, ventribiconvex (Pl. 6. Fig. 4c) to planoconvex or sometimes concavoconvex (Pl. 9, Fig. 2a; Table 1 ). Cardinal area orthocline. Anterior commissure rectimarginate in juveniles to very slightly sulcate in adults. Beak PLATE 6. Lenticellaria gregoryi sp. nov. Material collected by G. Willems from a tanker shipwreck at Kodingareng (Spermonde Archipelago, west of Makassar, South Sulawesi, Indonesia) at a depth of 30 m. Size of the specimens indicated with scale bars.

Fig. 1. RBINS-BT. 5. Paratype. Articulated specimen photographed with a macro-objective on a Pentax K20D. The general aspect of the shell (1a; 1b) is homeomorphic with juvenile specimens of Megerlia or Annuloplatidia curiosa Bitner, 2015 . The shell surface ornamentation is unclear as it is difficult to see if the shell surface is covered with spines or scales. Under a binocular microscope there appear to be numerous punctae (depending on the type of light).

Fig. 2. RBINS-BT. 6. Paratype, a ventral valve photographed with a macro-objective on a Pentax K20D. The typical parallel disposition of the punctae in the sessile pedicle collar is clearly visible.

Fig. 3. RBINS-BT. 4. Holotype photographed with a macro-objective on a Pentax K20D. 3a: external ventral view of the ventral valve. 3b: Internal aspect of the ventral valve with the sessile pedicle collar showing parallel disposition of the punctae. 3c: Internal dorsal view showing the brachidium and the very small crura.

Fig. 4. RBINS-BT. 5. Paratype. Articulated specimen observed with SEM at low magnification. External aspect of the shell is homeomorph with Megerlia . Thee shell is slightly dorsi-biconvex (4c; 4d; 4e). The dorsal valve is smooth (4a); The anterior commissure is slightly sulcate. The foramen is not abraded and is amphithyrid (4a; 4g). The extremely reduced brachidium is made of two claws and of two small crura (4f).

PLATE 7. Lenticellaria gregoryi sp. nov. Material collected by G. Willems. Figs. 1a–f and 2a–f: specimens from a shipwreck at Kodingareng (Spermonde Archipelago, west of Makassar, South Sulawesi, Indonesia) at a depth of 30 m. Figs. 3a–c: specimen from the “Liberty” shipwreck at Tulamben (Bali Sea, Bali, Indonesia) at a depth of 25 m. Size of the specimens indicated with scale bars.

Fig. 1. RBINS-BT. 5. Paratype. Articulated specimen observed with SEM at high magnification. External aspect of the shell. Radial rows of thick tubercles with shell surface between these rows of tubercles covered with small scales giving a “lenticel” aspect. At still higher magnification (1b–1f) the scales seen in anterior view appear as “Gaussian curves” (1e). a: dorsal view; b: anterior view; c: posterior view; d: dorsal view at very high magnification; e: anterior view at very high magnification; f: posterior view at very high magnification.

Fig. 2. RBINS-BT. 6. Paratype. Ventral valve. 2a: general ventral view; 2b: general internal view with sessile pedicle collar and low median septum interrupted in its posterior part; 2c: detail of external ornamentation with numerous small scales; 2d: detailed view of the sessile pedicle collar (with SEM the punctae are not visible); 2e; detailed view of the posterior part of the septum.

Fig. 3. RBINS-BT. 8. Paratype. Ventral valve. 3a: general ventral view; 3b: Scales ornamentation of shell surface at high magnification; 3c: general internal view with sessile pedicle collar and low septum interrupted in its posterior part.

PLATE 8. RBINS-BT. 4. Lenticellaria gregoryi sp. nov. Holotype collected by G. Willems from sieved sediment from a tanker shipwreck at Kodingareng (Spermonde Archipelago, west of Makassar, South Sulawesi, Indonesia) at a depth of 30 m. Detailed SEM views of both separated dorsal (Figs. 1a–g) and ventral (Figs. 2 a–f) valves. Size of the specimen indicated with scale bars.

Fig. 1. 1a: Internal view of the dorsal valve showing subcircular tubercles on the valve floor, short intact crura and symmetrical sharply pointed claws; b–c: detailed view of the brachidium in ventral view. The sharp tips of the loop are clearly visible as the crura. Cardinal process absent (1b). 1c: detailed view of the loop at high magnification in ventral view. 1d: Oblique lateral view; 1e Detailed view of the loop in anterior view 1f: Detailed view of the loop in lateral view; 1g detailed posterior view of the loop. (1e; 1g) show also that resorption process of cucullate structure has begun anteriorly; 1h: detailed view of the right crus; 1i: detailed view of the left crus.

Fig. 2. 2a: general view of the ventral valve in ventral view. Homeomorphy with Megerlia species is evident. 2b: anterior general view showing a “granulate” shell surface. 2c–f: Detailed SEM views of the external ornamentation of the shell surface. Numerous scales with Gaussian curve aspect visible together with larger tubercles. 2c–d: ventral view at moderate and higher magnification. 2e: anterior view; 2f: oblique left lateral view of left part of the shell. Low costae ornamented with tubercles are visible.

PLATE 9. Lenticellaria gregoryi sp. nov. Material collected by G. Willems from sieved sediment from a tanker shipwreck at Kodingareng (Spermonde Archipelago, west of Makassar, South Sulawesi, Indonesia) at a depth of 30 m. Detailed SEM views of separated ventral valve of the holotype (Figs. 1–ae) and illustration of an early juvenile articulated paratype (Figs. 2a–g).. Size of the specimen indicated with scale bars.

Figs. 1. RBINS-BT. 4. Holotype. 1a: general internal view of ventral valve in dorsal view. 1b: detailed view sessile pedicle collar and posterior interrupted portion of the ventral septum. 1c: detailed view of the cyrtomatodont tooth. 1d: general oblique lateral view illustrating the low ventral septum. 1e: anterior view of ventral valve.

Figs. 2. RBINS-BT. 7. Paratype. 2a: dorsal view of the articulated specimen. Dorsal valve smooth and foramen amphithyrid. 2b: Ventral view with rows of tubercles. 2c: detailed view of the ventral shell surface with scales between the radial rows of tubercles. 2d: high SEM magnification of the ornamentation of ventral shell surface. 2e: Opened articulated paratype showing the tuberculation of the dorsal valve floor and the brachidium. 2f: detailed view of the brachidium in dorsal view. Resorption of the anterior portion of the cucullate phase is started. Crura are appearing as very small knots. 2g: detailed anterior view of the cucullate phase showing the importance of the anterior resorption process at this stage of growth.

erect with obtuse umbo often abraded. Foramen amphithyrid, shared conspicuously by the dorsal valve in all stages of growth with convex dorsal side (Pl. 6, Figs. 4e–g). Deltidial plates poorly developed when preserved, elongate triangular, very narrow, disjunct. Dorsal valve always smooth. On the contrary, the ventral valve shows a clear radial tuberculation from the juvenile stage of growth (Pl. 6, Fig. 4b; pl. 7, Figs. 2a, 3a; Pl. 8, Figs. 2a–c; Pl. 9, Fig. 2b).

A very different aspect of the ventral valve is observed with a SEM used at a greater magnification. The structure is reminiscent of wood (Pl. 7, Fig. 3b). Spaces between the tuberculate radial rows are not smooth but ornamented with “stripes” oriented like the concentric growth lines. This is a striking distinction between this brachiopod and representatives of the genus Megerlia with a smooth or spiny shell surface between the tuberculate radial rows. However this morphological character is not easily seen with a binocular microscope and even with a SEM at low magnification (Pl. 7, Fig. 2a, and Pl. 7, Fig. 3a,). At still higher magnification, these “stripes” in dorsal view (Pl. 7, Figs. 1a, 1d, 2c, 3b) appear as minuscule scales with a “Gaussian curve” aspect in anterior view (Pl. 7, Fig.1b, 1e, 1f). Scales are densely present on all specimens found even on early juvenile shells (Pl. 9, Fig. 2b). These scales with “Gaussian curve” outline are different from the tubercles which are more similar to conical relief.

Obtuse hinge angle between 120° and 130°. Cyrtomatodont teeth curved, sharply ended and with a smooth surface. (Pl.7, Fig. 2d). Pedicle collar narrow and sessile (Pl. 7, Fig. 2f) fused with the underlying shell and appearing as a narrow thickening of the shell (Pl. 7, Fig. 2f). Shell endopunctate. Punctae of the pedicle collar parallel to the valve floor surface and perpendicular to the pores of the shell itself. This gives a characteristic striated aspect when observed with a binocular microscope (Pl. 6, Fig. 2). The number of punctae in the ventral valve varies around 294 punctae/mm².

Ventral valve with a low thin median septum always interrupted in its posterior part (Pl. 7, Fig. 2b, 2f, 3c; Pl. 9, Fig. 1b, 1e). This septum does not extend under the pedicle collar.

Inner dorsal valve floor radially tuberculate. Inner ventral valve floor not tuberculate.

Loop structure and ontogeny. The loop in the largest specimen is made of two crura and two claws only. This is always the case even in the most juvenile stage observed (Pl. 9, Figs. 2e–g). During growth, these claws widens and the space between the tip of the claws increases (Pl. 6, Fig. 4f; Pl. 8, Figs. 1b, 1e) but not regularly or linearly ( Table1 ). Crural bases are produced at an early stage of growth (Pl. 9, Fig. 2f) but crura do not grow significantly: they remain short. Crural processes and descending branches are never produced.

The ontogeny of this reduced brachidium begins as a typical Megerliinae process. The bifurcate septal pillar builds a posteriorly concave plate which becomes more conical. At this first stage the similarity with the ontogeny of Megerlia is evident. The resorption of the anterior part of this cucullate structure occurs at and just after the beginning. This resorption rapidly affects the anterior part of the cone and it continues posteriorly (Pl. 9, Fig. 2g). On the contrary, in Megerlia the resorption process begins posteriorly and stops before the anterior part could be dissolved (Pl. 3, Fig. 3e), building a ring. Later in L. gregoryi sp. nov. when the resorption process is finished it remains two claws which increase in size progressively through growth but which never conjoin to form a ring ( Table 1 ).

This is one of the most reduced loop developments observed in Kraussinoidea . There are no ring and descending branches like in Megerlia . Crural bases are developed but “ pro partim ” descending branches extending from the septum like flanges, as seen in Megerlina , are not produced. The wide Y-shaped septum of Kraussina is quite different. The loop of Pumilus antiquatus Atkins, 1958 is the nearest more or less comparable structure. However, all other morphological features in P. antiquatus are markedly different (Lee and MacKinnon, 2006).

Tables

TABLE 1. Lenticellaria gregoryi n. sp. Morphometric measurements were taken from the 14 measurable specimens extracted from the sieved sediments collected in the shipwrecks in Bali and in Makassar. L: length (mm); W: width (mm); T: thickness (mm); ØF: maximal width of the foramen (mm); Wbrach: maximum width of the brachidium (mm); ↔: distance between the acute tips of the brachidium (µm); L / W = ratio length to width, T / W = ratio thickness to width; ØF / W: ratio width of foramen to width. nm: value not measured. np: measure not possible (one tip is broken). “ No brach ”: the development of brachidium had not yet begun.

Specimens measured	L	W	T	L/W	T/W	Ø F/W	Ø F	Wbrach	↔
	mm	mm	mm				mm	mm	µm
Articulated specimens
Holotype RBINS -BT. 4	2.43	2.92	0.95	0.83	0.30	0.25	0.74	0.66	120
Paratype RBINS -BT. 7	1.45	1.38	0.35	1.05	0.26	0.33	0.45	0.25	4
Paratype RBINS -BT. 5	2.22	2.45	0.82	0.91	0.34	0.23	0.57	0.62	np
Smallest specimen	0.89	0.88	0.23	1.01	0.26	0.26	0.23	no brach	no brach
Largest specimen	2.54	3.35	0.63	0.76	0.19	0.23	0.76	0.71	110
Specimen from Makassar	1.74	2.38	0.68	0.73	0.29	0.22	0.52	0.51	160
Specimen from Makassar	1.60	1.89	0.56	0.85	0.30	0.23	0.43	0.43	60
Specimen from Makassar	1.75	1.98	0.89	1.13	0.45	0.26	0.52	0.50	39
Ventral valves
Paratype RBINS- BT. 6	1.87	2.43	nm	0.77		0.23	0.70
Specimen from Makassar	1.58	1.78	nm	0.89			nm
Specimen from Makassar	0.97	1.01	nm	0.96			nm
Paratype RBINS- BT. 8 (Bali)	1.80	2.14	nm	0.84			nm
Dorsal valves
Dorsal valve Makassar	nm	2.67	nm	nm			Br	0.76	np
Dorsal valve Makassar	nm	2.59	nm	nm			0.67	0.67	110
Mean value for all specimens	1.74	2.13	0.64	0.89	0.30	0.26	0.54	0.56	86
Number of specimens measured	12	14	8	12	8	9	9	9	7
Confidence interval				0.0356	0.0266	0.0122