The Fossil Record of the Haplosclerid Excavating Sponge Aka de Laubenfels J. REITNER and H. KEUPP Introduetion Only few publications deal with Recent species of the genus Aka or Siphono dietyon, a younger synonym of Aka (Johnson 1899; de Laubenfels 1936; Bergquist 1965; Rützler 1971; Thomas 1972; Pang 1973). In the literature, only' two publications figure and describe fossil Aka spicule arrangements -Müller (1978) and Reitner (1987a). Aka spicules are commonly found within burrows in Jurassie and Cretaceous shallow marine carbonates. The present chapter will document the stratigraphie occurrences, systematic and phylogenetic implications, as weIl as ecological interpretations, offossil Aka species (Fig. 1). Systematie Position of the Genus Aka The excavating sponge Aka is c1assified within the order Haplosclerida, family Adociidae, based on the oxea spicule type and its arrangement in bundles or brushes. The spicules of the inner parts of the sponge exhibit a typical adociid arrangement. Spongin is reduced and cortical spicule tracts are arranged perpendicular to the central spicule bundles. The whole sponge lives wholly inside calcareous material. Only prominent chimneys with apertures protrude from surfaces. Systematies and Stratigraphie Distribution of Fossil Aka Systematic Description ofEarly CamianAka Aka eassianensis n.sp. (Fig. 2a-d) Derivatio nominis: After the Lower Carnian Cassian Formation, named after the type locality, a small village near Cortina d'Ampezzo (Northern Italy). Holotype: Deposited in the Institut für Paläontologie der Freien Universität Berlin (IPFUB, JR5/89) Locus typicus: Seelandalpe near Schluderbach J. Reitner and H. Keupp (Eds.) Fossil and Recent Sponges © Springer-Verlag Berlin Heidelberg 1991 The Fossil Record of theHaplosc1erid Excavating Sponge A ka de Laubenfels Fig.l. Sketch oflivingA ka within Late Jurassic siliceous sponge habitats. Most sponges are dead and covered by bacterial crusts. The entire spicular skeleton is altered to ca1careous material. H Hexactinellid; L lithistid ; A Aka; C micritic crust Stratum typicum: Triassic, Early Carnian, Cassian Formation Material: 4 specimens Diagnosis: Encrusting and excavating Aka with relative short, but thick oxeas, arranged in brushes. Spicules connected with their end points as seen in Adocia Description ofthe holotype (Fig. 2a-d): Aka bores in a small chaetetid sponge. Six round-shaped to elongated boring cavities are visible. In two of these cavities cross-cut monaxonic spicules are visible. On the outer surface of the chaetetid sponge, Aka is cut obliquely. The sponge protrudes from the surface of the chaetetid sponge. The thick short oxeas are similar to those seen in the cavities. Therefore a dose relationship between the excavations and the protruding sponge is probable. The entire sponge is encrusted by dark, micritic, bacterial crusts. Spicule measurements: length: 620-900 /Lm, mean 740 p.m; width: 80-65 /Lm , mean: 70 /Lm. Diameter of the burrows: 16oo-400/Lm Diameter of the entire sponge: ca. 1.5 cm Description of the paratype (Fig. 3a-c): The described sponge is encrusting. Spicule type and arrangement are typical for Aka. The sponge is cut perpendicular to the axis of the spicule bundles and exhibits mostly cross-cut spicules. Onlya few spicules retain the entire shape. Within the center ofthe sponge, a hole is visible. The sponge remains are covered by dark, doudy, stromatolitic structures. The spicules are smaller than those measured in the holotype. Spicule measurements: length: 700-850 /Lm , mean 775 /Lm ; width: 75 /Lm 1. Reitner and H. Keupp Fig.2. Aka cassianensis n.sp. holotype; Cipit Boulders from the Cassian Beds near Seeland Alpe (Schluderbach, Northern Italy). a Entire sponge with boring cavities inside a small chaetetid sponge. Scale: 1 mm. b Spicular arrangement of the encrusting outer part of the sponge. Scale = I mm. e Elongated burrowing cavity with cross-sec ted spicule tracts. Scale = 500 I-'m . d Detail ofbshowing the short thick oxeas. Scale = 500l-'m The Fossil Record of the Haplosclerid Excavating Sponge Aka de Laubenfels Fig.3. Aka cassianensis n.sp. paratype; Cipit Boulders from the Cassian Beds near Seeland Alpe (Schluderbach, northern Italy). Specimen is covered by a dark micritic layer with stromatolitic affinities. Scale = 3a 400 Ilm, 3b 100 Ilm, 3e 200 Ilm Diameter of the entire sponge: ca. 10 mm Diameter of the central hole: 5 mm Differential diagnosis: The new species differs from all modern species by exhibiting significantly larger sc\eres. In modern A ka the spicules size varies from 100-200 I-tm. Within fossil Aka this particular type ofshort and thick oxea seen in Aka cassianensis is never observed. Remarks. From the Lower Carnian Cassian Formation of the Dolomites near Cortina d'Ampezzo (northern Italy), fore-reef debris flows are common containing excellently preserved coralline sponges. Most of these sponges are pre J. Reitner and H. Keupp served with their original mineralogy (aragonite, high Mg calcite) (Fürsich and Wendt 1977; Wendt 1979; Reitner 1987b; and others). The associated siliceous sponges are badly preserved because the siliceous spicules are dissolved very early. Only in few thin sections can the characteristic Aka spicules arranged in brushes and bundles be seen (Figs. 2-5). Systematic Descriptions ofJurassie and Cretaceous Aka Remarks. Most post Triassic Aka species possess a burrowing ability. Some encrusting specimens are observed within Bathonian siliceous sponge build-ups from St. Aubin-sur-Mer(Normandy).The spicule types and spicule arrangement ofthe encrusting and boring type are nearly similar. Only two new main types of Aka are described here. Based on the lack ofcharacters found in fossi l specimens, Fig.4. Aka cassianensis n.sp.; same locality as Fig. 2. Scale = 200 pm Fig.5. A ka cassianensis n.sp.; encrusting specimen. Same locality as Fig. 2. Scale = 2 mm The Fossil Record of the Haplosclerid Excavating Sponge Aka de Laubenfels it is always very difficult to erect new species, but the new observed forms significantly differ from modern ones and new species are justified. A ka muelleri n.sp. (Figs. 6-8) Derivatio nominis: After Walter Müller, a paleospongiologist who found and described the first, fossil Aka. Holotype: Deposited in the IPFUB, JR6/89 Locus typicus: Roß bach, north part of the Frankenalb in Bavaria Stratum typicum: Lower Kimmeridgian sponge mound facies Material: Numerous specimens from Jurassie and Cretaceous carbonate platforms and from calcareous organisms. Stratigraphie distribution: Bajocian-Late Cretaceous Geographical distribution: Middle and Western Europe, Arizona/Northern Mexico (Aptian/Albian Mural Limestone). Diagnosis: Irregularly shaped sponges ofvarious sizes which live exelusively in excavated burrows. The burrows are large and possess generally only one or two openings. The spicules (oxeas) are big and arranged in bundles and brushes. Sm aller ectosomal oxeas are observed in few specimens. Within the probable choanosomal area, the spicules exhibit typical haploselerid arrangements. The sponge bores only in calcareous material, such as corals, diagenetically altered siliceous sponges, coralline red algae, bivalves, and belemnites. Description of the holotype (Fig. 6): The sponge is located in an oyster shell wh ich is settled by thecidean brachiopods. The microfacies of the host rock is mudstone/wackestone. The micrite is eloudy and exhibits irregularly shaped elasts and tuberoids. Seven spicule tracts are visible which are cut vertically and oöliquely. A single spicule tract possesses more than 50 spicules. Two types of oxeas are observed: a rare smaller type in the outer part of the sponge remains, probably representing ectosomal seleres, and a bigger more common one in the center of the sponge. Small spicule types are observed also within the larger spicule tracts (bundles). Measurements: Big oxeas (3x): length: 1000-1600 /Lm; width: 60/Lm Small oxeas (2x): length: 800 -1200 /Lm; width: 20-25 /Lm Differential diagnosis: Aka muelleri n.sp. differs from Aka cassianensis n.sp. in the absence of an encrusting growth form and the possession of much larger seleres. The Recent Aka species have much smaller spicules (10 X smaller). Aka minima n.sp. (Figs. 9,10) Derivatio nominis: After the Latin word "minimus" small Holotype: IPFUB, JR7/89 Paratype: IPFUB, JR8/89 Locus typicus: Kasendorf, SW ofKulmbach, northern Bavaria (MFS 188); leg. T. Steiger, Munich Fig.6. Aka mue//eri n.sp. holotype; Kimmeridgian sponge mounds from RoBbach northern Frankenalb (southern Germany, Bavaria). Scale = 1 mm Fig.7. Aka muelleri n.sp. from Bajocian/ Bathonian sponge biostromes of Vilviestre (Sierra de la Demanda, northern Spain). Scale = 500 Ilm Fig.8. Aka muelleri n.sp. from a Late Albian reef (Albeniz/Eguino reef) near Araya (Prov. Alava, northern Spain). Aka bored within a specimen ofAcanrhochaeleles(deep fore-facies). Scale = 1mm The Fossil Record of the Haplosc\erid Excavating Sponge Aka de Laubenfels \09 Fig. 9. Aka minima n.sp. holotype; Kimmeridgian sponge mounds near Kasendorf (Southern Germany, Bavaria). Scale = 200 Jlm Fig. 10. Aka minima n.sp. paratype; Oxfordian/ Kimmeridgian from Laibarös (northern Frankenalb, South Germany, Bavaria). Aka bored in a belemnite guard. Scale = 500 Jlm J. Reitner and H. Keupp Stratum typicum: Sponge mounds of the Kimmeridgian Diagnosis: Aka with narrow long oxeas forming spicule bundles. Burrowing cavities elongated and in some cases branched. Description of the holotype (Fig. 9): Aka minima n.sp. is located within a thick brachiopod shell wh ich is totally bored with only thin walls between single sponge cavities. The new species Aka muelleri n.sp. is also common. Other fossils include brachiopods and lithistid sponges. Thebiogenetic pore space of the sponges filled up with pellets. The host microfacies is a tuberolithic filament-bearing wackestone/mudstone. Most bioclasts are surrounded by dark micritic crusts. The new A ka species is located in a large bore cavity ofa brachiopod and all cross-sections are visible. The spicules are arranged in loose bundles. The cavity ls elongated in contrast to the Aka muelleri cavities, wh ich are sack-shaped. The oxeas are thin and relatively long. Other spicule types are not observed. The inner zone ofthe sponge exhibits a dark micritic halo with rare spicules. The innermost zone of the halo is spicule free. The center of the sponge shows an elongated cavity, probably the main excurrent canal (spongocoel?). Measurements: Spicules: length: 300-600 /Lm, mean 400 /Lm; width: 15-25 /Lm, mean: 20/Lm Cavity: length: ca. 10 mm; diameter: 1-5 mm Paratype (Fig. 10): The paratype is located in a totally bored belemnite guard from the Oxfordian/Kimmeridgian boundary of Laibarös (northern Frankenalb, Bavaria). The sponge is relatively badly preserved. The spicules are concentrated in thick bundles. Only Aka minima n.sp. is observed within the belemnite guard. Measurements: Spicules: length: 400-640 /Lm, mean 500 /Lm; width: 15-25 /Lm , mean: 20/Lm Differential diagnosis: Aka minima n.sp. differs from Aka muelleri in having smalier spicules and more elongate burrowing cavities. Middle Jurassie Occurrences ofAka In the Celtiberic Ranges and the northern part ofSpain, vast carbonate platforms of Bajocian/Bathonian age are present (Hinkelbein 1975; Wilde 1988; Scheer 1988; and others). These platforms are constructed of rigid siliceous sponges, lithistid demosponges, and a smaller amount of hexactinellid sponges. Within these sponge build-upsAka muelleri n.sp. (Fig. 7) is a common boring organism. Measurements: Bigger oxeas: length: 1000-1500 /Lm ; width: 50-55 /Lm Smaller oxeas: length: 850-1000 /Lm; width: 50/Lm The Fossil Record ofthe Haplosclerid Excavating Sponge Aka de Laubenfels ' 111 Late Jurassie t Build-ups ofsiliceous rigid sponges are very common at this time in all ofEurope (especially in southern Germany) (Fritz 1958; Wagenplast 1972; Trammer 1982; Gaillard 1983; Flügel and Steiger 1981; Schorr and Koch 1985; and others). The main facies belts are more or less the same as those observed in the Dogger of Spain. The Late Jurassic occurrences are mostly in mud mounds and in some cases in mud banks ("Treuchtlinger Marmor"). The Oxfordian mounds are constructed main1y of hexactinellid sponges. The Kimmeridgian and Tithonian mounds and banks are composed mostly of lithistid demosponges. In both cases Aka is a common excavator within sponge skeletons. Aka muelleri n.sp. is the most common boring sponge. The smaller A ka minima n.sp. is rare and mostly associated together with Aka muelleri n.sp. Müller (1978) has reported Aka minima n.sp. within the lithistid sponge Pyrgochonina acetabulum (Goldf.) from the Lower Kimmeridgian of the Schwäbische Alb (southern Germany). He has found this new sponge also in hexactinellids, and therefore, he interpreted the new sponge as a parasitic organism. His observation was the first report of fossil A ka species. A ka bores exclusively in calcareous material. Therefore Aka is a postmortem inhabitant of siliceous sponges after a very early diagenetic replacement of the opal or cristobalite of the siliceousspicules into calcite. Aka bores in diagenetically altered sponge skeletons and in belemite guards. Measurements ofAka muelleri n.sp. (excI. holotype): Bigger oxeas: length: 1300-1550 /Lm, mean: 1450 /Lm; width: 55-60 /Lm, mean: 50/Lm Smaller oxeas: length: 700-1000 /Lm, mean: 900 /Lm; width: 15-20 /Lm, mean: 17/Lm Measurements ofAka minima n.sp. (excI. holotype): Oxeas of Müller specimen: lengt&: 350-470 /Lm , mean 450 /Lm ; width: 15 /Lm Oxeas offurther specimens: length: 320-620 /Lm , mean 500 /Lm ; width: 20/Lm Early Cretaceous In the Lower Cretaceous ofthe Tethyan realm ofEurope, as well as in the north part of the Cretaceous Gulf of Mexico, shallow marine carbonate platforms and reefs are widespread and called "Urgonian". The U rgonian facies of northern Spain is well studied, especially the facies distributions and the sponge communities (Pascal 1985; Reitner 1982, 1986, 1987a, 1987c; Reitner and Engesei 1983,1985,1987). The boring sponge Aka is common in the deeper part ofthe coralgal facies belt, within the Microsolena deeper water coral facies and within the Spirastrella (Acanthochaetetes) biofacies (Reitner 1987a, PI. 15, Figs. 5,6) (Fig. 8). Further occurrences ofAka are within micritic mud mounds which were formed by siliceous sponges, comparable with the Jurassic ones, and rarely:in rudist mud mounds. Within the beach facies and other permanently wavc;;-agi J. Reitner and H. Keupp tated faeies zones, typical pearl band borings of the hadromerid burrowing sponge Cliona are observed. Cliona borings are never seen within quiet water faeies in whieh Aka is dominant. Spieule type and spieule arrangements are eharaeteristie for the speeies Aka muelleri. The spieules are slightly smaller but they have the same shape and thiekness. Measurements: Oxeas: length: 800-1000 f.'m , mean 900 f.'m; width: 50-55 f.'m, mean 52 f.'m Midd/e Eocene Early Tertiary eoral reefs are rarely exposed and only few loealities are known. Generally the deeper parts of the fore-reefs of these distinet reefs are not preserved or exposed. From the Boltafia anticline in the southern Pyrenees Middle Eoeene debris flows are exposed, whieh bear eomponents of deeper fore-reef mud mound faeies. A strong freshwater diagenesis has dissolved out most ofthe aragonitie organi'sms, as evideneed by preserved ghost struetures. The faeies is eharaeterized by flat eorals, different enerusting eoralline red algae, enerusting rotaliid foraminifera, bryozoa, and sponges. A Spirastrella (Acanthochaetetes) eommunity eomposed of small S.(A.) eocena (Rios & Almela), different unidentified lithistid demosponges and Aka is observed. Nearly all larger ealcareous organisms are intensively bored by Aka and often only a vague reliet is preserved. TheA ka ea vities are often elongated or rarely saek-shaped. The living eavities of Aka exhibit a length of > 10 mm. Eaeh possesses one narrow opening. The spieules are enormous (1.5-2 mm) and are arranged in bundles. The number of spieule-bundles is highly variable and has therefore no taxonomie signifieanee. Two oxea size eategories are observed. A differentiation of spieules to dermal or ehoanosomal scleres are not seen. The spieule-bundles are eovered by dark mieritie halos. The sponge differs from all other fossil Aka in eavity size and shape, spieule size, and habitat. Therefore a new speeies is ereated. Systematic Description A ka boltanaensis n.sp. (Figs. 11-13) Derivatio nominis: After the loeus typieus the village Boltafia in the southern Pyrenees. Holotype: Deposited within IPFUB, JR9/89 Loeus typieus: Base ofthe Boltafia-anticline near a parking lot on the south side of the river. Stratum typieum: Middle Eoeene debris flow Material: 5 speeimens Diagnosis: Very big Aka exeavating single elongated or saek-shaped borings, opened at one end. The spieules exhibit two sizes, a large one with a mean size of Fig. 11. A ka bollanaensis n.sp. holotype; Middle Eocene elast within a debris !low of the same age from the Boltana Anticline near Boltana (southern Pyrenees). Aka boring in a large cora!. Scale = I mm Fig.12. Aka bollanaensis n.sp. Living cavity with a prominent bottle neck canal which serves as the connection between the outer and inner sponge tissue. Same locality as Fig. 10. Scale = 500/Lm Fig.13. Aka bollanaensis n.sp. Characteristic elongated canals in the living cavity ofthis particular species. Scale = 2 mm J. Reitner and H. Keupp 1600 ILm and a smaller one with a mean size of 500 ILm. The thickness of the spicules varies from 80-20 ILm. The ratio of length to thickness shows a long narrow spicule character. Description of the holotype (Fig. 11): The holotype ofAka boltanaensis is in a thin section from the Spirastrella (Acanthochaetetes) community mud mound facies. Flat coral remains are common, as weIl as larger rotaliid foraminifera (Nummulites sp.), and coralline red algae. The holotype is found in the remains of a thamnasteroid scleractinian coral. The coral is totally bored. The coral skeleton is preserved in granular neomorphic calcite. The big Aka-boring (living cavity) has a measured length of2 cm and a maximum diameter of9 mm. Several smaller blind cavities are observed extending from the main cavity are observed. These blind cavities are filled with spicules and probably served as mining areas for the sponge immediately before its death. The living cavity ofthe sponge is a complicated three dimensional network, as evidenced by vertical and oblique cuts of the spicule-bundles and Y -shaped areas connecting the cavities. Measurements: Bigger oxeas: length: 1400-2200 ILm, mean 1700 ILm; width: 60-80 ILm, mean 75 ILm Smaller oxeas: length: 300-1000 ILm, mean: 560 ILm; width: 20-40 ILm, mean 35 ILm Differential diagnosis: A ka boltanaensis n.sp. differs in first order from all known A ka species in having very large, elonga ted two size ca tegories oxeas. A ka muelleri n.sp. has similar-sized spicules and also possessing two sizes of oxeas. The measured dimensions are slightly smaller and the length/thickness ratio is smaller, than in Aka boltanaensis. Nevertheless, both species are closelyrelated. The living cavity ofAka boltanaensis is much more complicated than seen in other fossil Aka. All RecentAka have spicules with length of 100-300 ILm. RecentAka Aka in Petrobiona massiliana Vacelet and Levi, 1958 One species is a common boring sponge inside the dead body of a pharetronid sponge Petrobiona massiliana Vacelet and Levi (Figs. 16,17) from submarine caves near M.lfseille (Mediterranean Sea). The spicule shape is typical for Aka minuta Thomas, a Pacific species, but the spicule size is bigger (mean 205 ILm), as Fig. 14. Aka coralliphaga (Rützler). Spicule bundles of the central part of an outdoor chimney. Curacao, Playa Kalki (10-20 m) CoLlected by van Soest. (Scanning electron microscope (SEM) micrograph) Fig. 15. Aka aff. coralliphaga inside the coralline sponge Astrosclera willeyana Lister exhibiting a pitted surface caused by boring activity. The dissolution marks are similarto those observed in Cliona. (SEM) micrograph) The Fossil Record of the Haplosclerid Excavating Sponge Aka de Laubenfels Fig. 16. Aka cf. minula Thomas inside the dead portion of Pelrobiona massiliana Vacelet & Levi. Submarine cave near Marseille. (SEM micrograph) Fig. 17. A ka cf. minuta Thomas inside the basal skeleton of Pelrobiona with living sponge in an endolithic chamber and narrow incurrent and outcurrent canals. Submarine cave near Marseille. Scale = 200 p.m J. Reitner and H. Keupp observed within the type material ofAka minuta (mean size of 120 /Lm) (Thomas 1972). ThereforeAka in Petrobiona are classified asAka cf. minuta. The spicules are arranged in bundles and brushes and the entire shape is comparable with the fossils species. Within the dead skeleton ofPetrobiona, many endolithic sponges are present. Beside Aka, Cliona is a rare excavating sponge. In cavities caused by the boring activity of excavating sponges, parasitic nonburrowing sponges settled. In the studied material Agelas sp., Geodia sp., and Clathrina sp. are found. The spicules ofAka cf. minuta are much smaller than those observed in all described fossilAka. The shape of the living cavities are comparable. In most cases sack-shaped cavities are observed. Measurements: Spicules: length: 170-215 /Lm, mean 200 /Lm; width: 7.5-10 /Lm, mean 8 /Lm Aka coralliphaga (Rützler) In Caribbean reefs Aka coralliphaga (Rützler) dominantly bores in fiat corals (Fig. 14). The species was erected by Rützler (1971) and described as "Siphonodictyon" coralliphagum (p. Siphonodictyon Bergquist 1965 is a younger synonym of Aka de Laubenfels 1936). Aka coralliphaga is also very common inside the dead parts ofIndopacific coralline sponges, e.g., Astrosclera willeyana (Fig. 15). Rützler (1971) has described different morphotypes of this species which he called "s." corlllliphagum forma typica, forma obruta, forma tubulosa, and forma incrustans. These morphotypes indicate that, as he considered, the various forms are different growth stages outside the living cavities. Beside ontogenetic growth stages an adaptation to water currents is probable. The morphotype forma tubulosa is here selected. The forma tubulosa is characterized by having a chimney-like main excurrent opening (spongocoel). The spicules in this area are arranged in thick bundles from which perpendicular smaller spicule tracts derive, forming the dermallayer. The center ofthe sponge exhibits typical adociid spicules connections. The spicules are arranged in bundles. For further descriptions see Rützler (1971). Measurements: Spicules: length: 150-200 /Lm, mean 170 /Lm; width: 7-9 /Lm, mean 7.5 /Lm Paleoecology and Biostratinomic Implications All observed fossil and modern occurrences of Aka are more or less found in protected habitats far from very turbulent water. Rützler (1971) noticed that the main depth distribution of Aka from the Caribbean is between 10-70 m, below the direct infi uence ofnormal wa ve action. Stead y wa ter currents were measured and are probably important for feeding. Aka is sometimes found in protected shallowerwaterenvironments (1-2 m waterdepth), e.g.,A ka coralliphaga is often found in boulder-like corals which are bored by Cliona spp. The Fossil Record of the Haploscierid Excavating Sponge A ka de Laubenfels Within the turbulent zones, the most species ofthe genus Cliona occupies the ecologi~al niche ofAka. Cliona is rarely observed in deeper water (Cliona viridis, Leptoseris reefs, 90 m), and within West Indies reefs Cliona delitrix, C. agrica, C. langue, and C. schmidti is common at 20 m water depth. The main depth distribution of Cliona is between 0-10 m (Rützler 1973, 1974; Schwarz 1981). Cliona is also observed in cooler, temperate water. Temperature seems also to be an important limiting factor ofthe Caribbean A ka communities. Within the northern Bermuda reefs A ka is not observed. From the Mediterranean, Aka is observed only in underwater caves, which are characterized by communities comparable with some Tethyan Cretaceous and modern Indopacific ones. These communities are primary Tethyan relicts (Reitner 1989). Perhaps Aka in Petrobiona is part ofthe primary Tethyan sponge community. This idea is supported by the existence ofAka as part ofthe Eocene Spirastrella/ Acanthochaetetes community from the southern Pyrenees. Aka in Petrobiona is a probable Tethyan survivor and specially adapted to moderate temperate water. Aka bores calcareous material, like Cliona. Aka produces the same type of boring chip as seen with Cliona and its boring method is comparable to Cliona (Pomponi 1980). The diameter ofthe etching chips ofAka varies from 14-40 I-tm, mean 30 I-tm and therefore comparable with the sponge chips of Cliona (Pomponi 1980). Similar ecological paleoenvironments of Aka are observed in all fossil Aka examples. Aka is also missing from high turbulent water facies zones. In this particular zone Cliona borings rarely exist (Reitner 1987a). Aka is common within the reef core, fore-reef, and mud mound facies which are always below normal wave base. In two reefs from the Late Albian Albeniz/Eguino platform in northern Spain, water depth of the coralgal reef core to fore-reef slopes was calculated as 30-100 m (Reitner 1987a) -the main distribution of Aka. The Late Carnian Aka are part of the highly diverse coralline sponge community ofthe Cassian reefs. These sponge communities are normally located in mound structures of the deeper fore-reef. The platforms are constructed of algae and oolite shoals. The bathymetric position of the Jurassic siliceous sponge mounds is still under discussion. The first studies on these build-ups mentioned a deeper water position based on the lack of true algae, and the presence of micritic sediments. Also the sedimentary megacycle of the Malm of southern Germany indicates a regressive sequence. On the top of sponge mounds, coral reefs were established during the Tithonian and demonstrate shallow marine water conditions. Based on "J. Walther's law" the sponge mounds must be situated in deeperwaters (Fritz 1958; Dwinner 1962; Nitzopoulos 1974; Ziegler 1977). New studies on the diagenetic seq uences of these mounds and bank facies indicate a contradictory bathymetric position within extremely shallow marine waters (intertidal). These conclusions are mainly based on marine vadose cements (Koch and Schorr 1986). Lang (1988) and Kott (1989) postulated a paleobathymetric position for the Oxfordian and Kimmeridgian sponge biostromes and mounds, based on sedimentological criteria, between normal wave base and storm wave base. All J. Reitner and H. Keupp these interpretations, however, indicate a restricted water movement: the optimal environment for A ka. Ofspecial importance is the boring activity ofAka in dead siliceous sponges which are often still in original life position. Aka and Cliona bore only in calcareous material; therefore, the siliceous skeletons ofsponges must be altered into calcite before A ka starts excavating. Most of the siliceous sponges are surrounded by dark micritic, partially stromatolitic halos. This feature indicates a reduced sedimentation rate; the siliceous sponges are not totally covered by sediment during this stage. The micritic crusts are called "Kalkmumien" (Fritz 1958). These micritic covers are cemented very early before the siliceous spicules are dissolved (cf. Brachert et al. 1987; Lang and Steiger 1984). The micritic layers are probably bacterial crusts decomposing the sponge soft tissue. One characteristic of these bacteria crusts is the synvivo lithification outside their cell walls. The dissolution ofthe siliceous scleres occurred after this early diagenetic event. Then the organic axial filaments were also decomposed by bacteria. These processes produced high pR values wh ich probably were responsible for dissolving the spicule cristobalite (Land 1976; Reitner 1986). The sclere molds were cemented rapidly by granular or single calcite crystals. After this diagenetic stage, Aka was able to bore inside the "siliceous" sponges. Aka is an important post mortem organism of siliceous sponge mounds. This diagenetic process is found in Jurassic as weIl as Cretaceous deeper water mud mound. Aka is therefoie an excellent indicator for a very early submarine cementation and diagenesis. The common Aka within the Middle Eocene reef rocks also indicate quiet water conditions of this particular biofacies. This biofacies is characterized by Spirastrella (Acanthochaetetes) , a sponge wh ich prefers dark and/or deeper water conditions. Conclusions I. The new Lower Carnian species A ka cassianensis is a dominantly encrusting sponge. Borings are only known from the holotype. Spicule shape and arrangement are similar to those in the modern genus Aka but the size is different. 2. Jurassic to Recent Aka are dominantly excavating sponges. 3. Two new species are described from the J urassic and Lower Cretaceous, A ka muelleri, and Aka minima. Aka muelleri n.sp. is the most common species. 4. From Middle Eocene fore reefsediments ofthe southern Pyrenees a further new species is described (Aka boltanaensis). 5. Recent species ofAka differ in having much smaller oxeas (100-200 /Lm) in relation to fossil ones (300-2200 /Lm) . 6. Aka prefers deeper, moderately agitated water conditions (20-100 m), as evidenced by modern occurrences and by facies analyses of fossil occurrences. The niches for boring sponges in shallower more agitated environ The Fossil Record of the Haplosclerid Excavating Sponge Aka de Laubenfels ments are preferred occupied by certain species of the hadromerid genus Cliona. 7. Aka is an excellent indicator for very early carbonate cementation and replacement ofthe siliceous spicules in calcite in fossil siliceous spünge mud mounds. Aka is an important post-mürtem faunal element in these particular build-ups (Fig. 1). A cknowledgments. The authors are indebted to Prof. Dr. R. van Soest (Amsterdam) for allowing the authors to study Recent Aka species and some donations. We thank Dr. E. Gierlowski-Kordesch (Freie Universität Berlin) for translation assistance and Dr. S. Pomponi (Harbor Branch Inst., Florida) for reviewing the ms. The Deutsche Forschungsgemeinschaft is acknowledged for financing this investigation (Re 6651-1 , Ke 32214). References Berquist PR (1965) The sponges of Micronesia, Part I: the Palao Archipelo. Pac Sci 9: 123-204 Brachert T, Dullo WC, Stoffers P (1987) Diagenesis of siliceous sponge limestones from the Pleistocene ofthe Tyrrhenian Sea (Mediterranean Sea). Facies 17:41-50 Oe Laubenfels MW (1936) A comparison of the shallow water sponges near the Pacific end of the Panama Canal with those at the Caribbean end. Proc US Natl Mus 83:441 -466 Flügel E, Steiger T (1981) An Upper Jurassic sponge-algal buildup from the Northern Frankenalb, West Germany. SEPM Spec PubI30:371-397 Fritz GK (1958) Schwammstotzen, Tuberolithe und Schuttbreccien in Weißen Jura der Schwäbischen Alb. Arb Geol Paläont Inst TH Stuttgart NF 13: 1-118 Fürsich FT, WendtJ (1977) Biostratinomy and palaeoecology ofthe Cassian Formation (Triassic) of the southern Alps. Palaeogeogr Palaeoclimat PalaeoecoI22:257-323 Gaillard Ch (1983) Les Biohermes a Spongiaires et leur Environment dans I'Oxfordien du Jura Meridional. Doc Lab Geol Lyon 90: 1-515 Gwinner MP (1962) Geologie des Weißen Jura der Albhochftäche (Württemberg). N Jb Geol Paläont Abh 115:137-221 Hinkelbein K (1975) Beiträge zur Stratigraphie und Paläontologie des Jura von Ostspanien, VIII : Stratigraphie und Fazies im Mitteljura der zentralen Iberischen Ketten. N Jb Geol Paläont Abh 148:139-184 Johnson JY (1899) Notes on some sponges belonging to the Clionidae obtained in Madeira. J R Microsc Soc 1899:461-463 Koch R, Schorr M (1986) Diagenesis of Upper Jurassic sponge-algal reefs in SW Germany. In : Schroeder JH, Purser BH (eds) ReefDiagenesis. Springer, Berlin Heidelberg New York Tokyo, pp 224-244 Kott R (1989) Fazies und Geochemie des Treuchtlinger Marmors (Unter-und Mittel-Kimmeridge, Südliche Frankenalb). Berliner Geowiss Abh 111: 115 pp Land LS (1976) Early dissolution ofsponge spicules from reef sediments, North Jamaica. J Sed Petrol 48 :337-344 Lang B (1988) Baffling, binding or debris accumulation? Ecology of Jurassic sponge-bacterial build-ups (Oxfordian, Franconian Alb). Berl Geowiss Abh 100:22 p Lang B, Steiger T (1984) Paleontology and diagenesis ofUpper Jurassic siliceous sponges from the Mazagan Escarpement. Oceanol Acta 1984 :93-100 Müller W (1978) Beobachtungen zur Ökologie von Kieselspongien aus dem Weißen Jura der Schwäbischen Alb. Stuttg Beitr Naturkd Ser B 37: 15 Nitzopoulos G (1974) Faunistisch-ökologische, stratigraphische und sedimentologische Untersuchungen an Schwammstotzen-Komplexen bei Spielberg am Hahnenkamm. Stuttg Beitr Naturkd B 16:1-143 120 J. Reitner and H. Keupp: The Fossil Record ofthe Haplosclerid Excavating Sponge Pang RK (1973) The systematics of some Jamaican excavating sponges. Postilla Peabody Mus Yale Univ 161 :1-75 Pascal A (1985) L'Urgonieu, systemes biosedimentaires et tectogenese. Mem Geol Ann Dijon 9 :45-72 Pomponi SA (1980) Cytological mechanisms ofcalcium carbonate excavation by boring sponges. Int Rev CytoI65:301-319 Reitner J (1982) Die Entwicklung von Inselplattformen und Diapir-Atollen im Alb des BaskoKantabrikums (Nordspanien). N Jb Geol Paläont Abh 165:87-101 Reitner J (1986) A comparative study of the diagenesis in diapir-infiuenced-reef atolls and a fault block reef platform in the Late Albian of the Vasco-Cantabrian Basin (Northern Spain). In : Schroeder JH, Purser BH (eds) ReefDiagenesis. Springer, Berlin Heidelberg New York Tokyo, pp 186-209 Reitner J (I987a) Mikrofazielle, palökologische und paläogeographische Analyse ausgewählter Vorkommen fiachmariner Karbonate im Basko-Kantabrischen Strike Slip Fault-Becken-Systein (Nordspanien) an der Wende von der Unterkreide zur Oberkreide. Doc Nat 40:248 Reitner J (\987b) A new calcitic sphinctozoan sponge belonging to the Demospongiae from the Cassian Formation (Lower Carnian; Dolomites, Northern Italy) and its phylogenetic relationship. Geobios 20:571-589 Reitner J (l987c) Phylogenie und Konvergenzen bei rezenten und fossilen Calcarea (Porifera) mit einem kalkigen Basalskelett ("Inozoa, Pharetronida"). Berl Geowiss Abh 86:87-125 Reitner J (1989) Lower and Mid-Cretaceous Coralline Sponge Communities of the Boreal and Tethyan Realms in Comparison with the Modern Ones -Palaeoecological and Palaeogeographic Implications. In: Wiedmann J (ed) Cretaceous of the Western Tethys. Proceedings 3rd International Cretaceous Symposium, Tübingen 1987 pp 851-878. E Schweizerbart'sche Verlagsbuchhandlung Stuttgart Reitner J, Engeser T (1983) Contributions to the systematics and the palaeoecology of the family Acanthochaetetidae (Fisher 1970) Order Tabulospongida, Class Schlerospongiae. Geobios 16:773-779 Reitner J, Engeser T (1985) Revison der Demospongier mit einem thalamiden aragonitischen Basalskelett und trabekulärer Internstruktur ("Sphinctozoa" pars) Berl Geowiss Abh 60: 151 -193 Reitner J, Engeser T (1987) Skeletal structures and habitates of Recent and fossil Acanthochaetetes (subclass Tetractinomorpha, Demospongiae, Porifera). Coral Reefs 6: 151 -157 Rützler K (1971) Bredin-Archold Smithsonian Biological Survey of Dominica: Burrowing Sponges, Genus Siphonodictyon Bergquist, from the Caribbean. Smith Contrib Zool77:17 Rützler K (1973) Clionid sponges from the coast ofTunisia. Bull Inst Natl Sci Tech Oceanogr Peche Salammbo 2(4):623-636 Rützler K (1974) The burrowing sponges from Bermuda. Smith Contrib ZooI165:203-216 Scheer U (1988) Infiuences of the paleogeographic position and sea-Ievel changes on· spongiolithic limestones in the lower Bajocian in northern Spain. Berl Geowiss Abh 100:36-37 Schorr M, Koch R (1985) Fazieszonierung eines oberjurassischen AIgen-Schwamm-Bioherms (Herrlingen, Schwäbische Alb). Facies 13:227-270 Schwarz A (1981) Zur Taxonomie und Ökologie der Bohrschwämme (Clionidae) im Felslitoral am Capo Caccia (NW-Sardinien) und deren geographische Verbreitung. Hausarbeit der Ersten Staatsprüfung rur das Lehramt am Gymnasium Wiss Prüfungsamt Bochum, pp 133 Thomas PA (1972) Boring sponges of the reefs of the Gulf of Mannar and Palk Bay. Proc I. Symp Corals and Coral Reefs 1969 Mar Biol Assoc India, pp 333-362 Trammer J (1982) Lower to Middle Oxfordian sponges ofthe Polish Jura. Acta Geol Pol 32: 1-39 Valelet J,oLevi C (1958) Un cas de survivance en mediterranee du groupe d'eponges fossiles des Pharetronides. CR Acad Sci 246 :318-320 Wagen plast P (1972) Paläoökologische Untersuchungen der Fauna aus Bank-und Schwammfazies des Weißen Jura der Schwäbischen Alb. Arb Inst Geol Paläont Univ Stuttg NF 67: 1-99 Wendt J (1979) Development of skeletal formation, microstructure, and mineralogy of rigid calcareous sponges from the Late Palaeozoic to Recent. Coll Int CNRS 291 :449-457 Wilde S (1988) The Vpper Bajocian-Lower Bathonian (Middle Jurassic) of the Northwest Iberian Range (Spain) -a spongiotuberolithic platform environment. Berl Geowiss Abh 100:52 Ziegler B (1977) The "White" (upper) Jurassic in southern Germany. Stuttg Beitr Naturk Ser B 26:79