A New Hexacoral Species from the Upper Jurassic to Lower Cretaceous Yura Group

at Cailloma, Arequipa Department, Southern Peru

Nobuo Y A M A G I W A , Cesar R A N G E L Z A V A L A , E v a V I L L A C I C E N S I O de D A V I L A

and Tetsuya K A W A B E

Reprinted from the Palaeontological Study on the Andes (II) , Geological Laboratory, Faculty of Science,

Chiba University 1981

A New Hexacoral Species from the Upper Jurassic to Lower Cretaceous Yura Group

at Cailloma, Arequipa Department, Southern Peru*

Nobuo Y A M A G I W A Department of Earth Science, Faculty of Education, Osaka Kyoiku

University, Osaka 543, Japan

Cesar R A N G E L Z A V A L A Instituto de Geologia, Mineria y Metalurgia, Ministerio de Energia y

Minas, INGEMMET, JesHs Maria, Lima, Peru

E v a V I L L A C I C E N S I O de D A V I L A

Instituto de Geologia, Mineria y Metalurgia, Ministerio de Energia y Minas, INGEMMET, JesHs Maria, Lima, Peru

and

Tetsuya K A W A B E Department of Earth Sciences, Faculty of Science. Chiba University,

Chiba 260, Japan

A b s t r a c t

Recently, an i n t e r e s t i n g hexacoral specimen was collected by I n g . D a v i d D A V I L A f r o m limestone i n the Upper Jurassic to L o w e r Cretaceous Y u r a Group** outcropping at 2 2 k m west of Cailloma, Arequipa Depar tment , Southern Peru . The present w o r k is based on th i s specimen, and a new hexacoral species, Actinastrea caillo­mensis is described.

* This study is a result of the cooperative works of Chiba University Palaeontological Party on the Andes and the Geological Survey of Peru (Instituto de Geologia, Mineria y Metalurgia, Ministerio de Energia y Minas. I N G E M M E T ) .

** The Y u r a Group has been studied by many investigators; J E N K S (1946, 1956), B E N A V I D E S (1962), W I L S O N & G A R C I A (1962), G A R C I A (1968), G U E V A R A (1968), P E C H O

& M O R A L E S (1968), G U I Z A D O (1968), B E L L I D O (1969), V A R G A S (1970), P E R A L E S (1970) and M O R A L E S (1977).

4 1

N . Y A M A G I W A , C . R A N G E L Z A V A L A . E v a V I L L A C I C E N S I O de D A V I L A and T . K A W A B E

Systematic D e s c r i p t i o n

by Y A M A G I W A

Order Scleractinia B O U R N E , 1 9 0 0 Suborder Astrocoeniina V A U G H A N & W E L L S , 1943

F a m i l y Astrocoeniidae K O B Y , 1 8 9 0 Subfami ly Astrocoeniinae K O B Y , 1 8 9 0

Genus Actinastrea O R B . , 1 8 4 9 Actinastrea caillomensis n . sp.

P I . 1, F igures la-c

Coral lum massive and cerioid. Corall ites subprismatic i n shape, usually five or six sided; most ly 2 . 3 to 2 .5 m m i n inside diameter i n m a t u r e stage. Coral l i te w a l l r e l a t i v e l y t h i c k . I t s thickness 0 .3 to 0 .7 m m . Centra l distance 2 .5 t o 3 .5 m m . Septa s t r a i g h t and t h i c k . The i r la tera l surface commonly smooth. They are 2 4 i n number i n m a t u r e stage, arranged i n three cycles. Those of the first t w o cycles long and usually contact w i t h a columella. Those of the t h i r d cycle v e r y short and free t o the first t w o cycles'. Columella s t y l i f o r m and usually thickened by secondary deposits.

I n l o n g i t u d i n a l section, t a b u l a r - l i k e endothecal dissepiments 7 per 2 m m i n average.

Inside diameter of corall ites Number of long septa

2.3 t o 2 .5 m m 12 2.0 to 2 . 1 m m 11 1.6 to 1.7 m m 10

Remarks: The present f o r m much resembles Actinastrea kellumi ( W E L L S , 1946, p. 2, p i . 1 , fig. 1) f r o m the Upper Jurassic L a Casita F o r m a t i o n , N o r t h e r n Mexico i n h a v i n g subprismatic corall ites of almost same size, 24 septa arranged i n three cycles, t h i c k and long septa of the first t w o cycles, v e r y short septa of the t h i r d cycle, t h i c k coral l i te w a l l . However , the f o rmer ' s septa are commonly

42

ies.t .s- ' i .T l)fl« h A New Hexacoral Species in Peru

smooth on t h e i r l a t e ra l surface, and the l a t t e r ' s ones have s t r o n g l y spines on t h e i r la tera l surface. I t is s imi lar to a specimen described by W E L L S (1953, p. 3, f i g . 1) as Astrocoenia cf. lissoni f r o m the L o w e r Jurassic Chocolate Format i on i n Southern Peru i n many respects. However , the f ormer ' s septa of the t h i r d cycle are free and not contact w i t h those of the second, and the l a t t e r ' s p a r t l y contact w i t h those of the second. Besides, the f o rmer has t h i n n e r coral l i te w a l l and somewhat longer inside diameter . I t is also re lated to Actinastrea sp. aff. A. globosa described by F E L I X (1891, p. 156) f r o m the Neocomian i n Mexico. According to h i m , the l a t t e r ' s septa of the second cycle are somewhat shorter t h a n those of the f i r s t . Actinastrea budaensis ( W E L L S , 1933, p. 160, p i . 6, f ig . 3) f r o m the Cenomanian Buda Limestone i n Texas is also al l ied to the present f o r m . However , the f o rmer ' s septa of the t h i r d cycle poorly developed and sometimes absent. Moreover, the f o rmer ' s septa of the t h i r d ones o f t fuse by t h e i r inner ends to the septa of the second. I t can be dist inguishable f r o m Actinastrea lissoni (T iLMAN, 1917, p. 701, p i . 26, figs. 4a-b) f r o m the Lias i n Peru and A. hexamera ( F R I T Z E , 1924, p. 318, p i . 3, f ig . 7) f r o m the Neocomian i n Chile i n h a v i n g larger coral l i tes .

Occurrence: I t occurs f r o m limestone i n the Upper Jurassic t o L o w e r Cretaceous Y u r a Group at 22 k m west of Cailloma, Arequipa Department , Southern Peru .

Collector: D a v i d D A V I L A . Repository: Reg. no. OKES810101 (holotype) (Department o f

E a r t h Science, Osaka K y o i k u U n i v e r s i t y ) .

A c k n o w l e d g e m e n t s

The w r i t e r s express t h e i r h e a r t y thanks to I n g . D a v i d D A V I L A ( I n s t i t u t o de Geologia, Miner ia y M e t a l u r g i a , Min i s ter i o de Energ ia y Minas, L ima) who p e r m i t t e d t h e m t o s tudy the present i n t e r ­est ing specimen, to Pro f . Shiro M A E D A (Chiba U n i v e r s i t y ) and Director Benjamin M O R A L E S A R N A O ( I n s t i t u t o de Geologia, M i n e r i a

43

N . Y A M A G I W A , C . R A N G E L Z A V A L A , E v a V I L L A C I C E N S I O de D A V I L A and T . K A W A B E

y M e t a l u r g i a , Min is ter io de Energ ia , L ima) f o r t h e i r k i n d advice and encouragement t h r o u g h o u t the present s tudy . Thanks are also due to D r . Sumio S A K A G A M I (Chiba U n i v e r s i t y ) and D r . Tomoki K A S E (Nat ional Science Museum, Tokyo) f o r t h e i r k i n d advice. Photographic w o r k was done by M r . Ken- i ch i N A R U H A S H I , Miss. N o r i k o M U R A K I and Miss K a o r u H I R O S E t o whom the w r i t e r s extend t h e i r thanks .

References

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B E N A V I D E S , V . ( 1 9 6 2 ) : Estratigrafia Pre-Terciaria de la region de Arequipa. Bol. Soc. Geol. Peru, 38.

F E L I X , J . ( 1 8 9 1 ) : Versteinerungen aus der Mexicanischen J u r a - und Kreide-Formation. Palaeontographica, B d . 37.

F R I T Z E , C . H . ( 1 9 2 4 ) : Neue Kreidefaunen aus Sijdamerika. N. Jahrb., B. B, 5 0 . G A R C I A , W . ( 1 9 6 8 ) : Geologia de los cuadrangulos de Mollendo y L a Joya. Bol. Cart.

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(23) .

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M O R A L E S , B . ( 1 9 7 7 ) : Sinopsis Expl icat iva del Mapa Geologlco del Peru (Escala 1: 1 , 0 0 0 , 0 0 0 ) . Bol. Cart. Geol. Nac. Peru, ( 2 8 ) .

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del Peru . Primer. Congreso. Latino Americano de Geologia. Lima. T I L M A N N , F . ( 1 9 1 7 ) : Die Fauna des unteren und mittleren L i a s in Nord- und Mittel-

Peru. N. Jahrb. Min., B. B., 4 1 . V A R G A S , L . ( 1 9 7 0 ) : Geologia del cuadrangulo de Arequipa. Bol. Cart. Geol. Nac.

Peru, ( 2 4 ) . W E L L S , J . W . ( 1 9 3 3 ) : Corals of the Cretaceous of the Atlantic and Gulf Coastal

Plains and western interior of the United States. Bull. Am. Pal., 1 8 . W E L L S , J , W . ( 1 9 4 6 ) : Some Jurassic and Cretaceous corals from Northern Mexico.

Jour. Pal., 20 , ( 1 ) . W E L L S , J . W . ( 1 9 5 3 ) : Mesozoic invertebrate faunas of Peru . pt. 3. Lower Jurassic

corals from the Arequipa Region. Amer. Mus. Novit., ( 1631) . W I L S O N , J . J . and G A R C I A , A . ( 1 9 6 2 ) : Geologia de los cuadrangulos de Pachia y Palca.

Bol. Cart. Geol. Nac. Peru, ( 4 ) .

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E x p l a n a t i o n o f P la te 1

F i g s . l a - c . Actinastrea caillomensis n. sp. l a . Transverse section x 4.0 ( O K E S 810101a) l b . Transverse section x 4.0 ( O K E S 810101b) I c . Longitudinal section x 4.0 ( O K E S 810101c)

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Y A M A G I W A et al.: A New Hexacoral Species in Peru Plate 1