Chaetosalpinx tapanilai

Ernst, Andrej, Taylor, Paul D. & Bohatý, Jan, 2014, A new Middle Devonian cystoporate bryozoan from Germany containing a new symbiont bioclaustration, Acta Palaeontologica Polonica 59 (1), pp. 173-183 : 177-179

Chaetosalpinx tapanilai ichnosp. nov.

Fig. 5 .

Etymology: Named for Leif Tapanila (Idaho State University) in recognition of his work on bioclaustrations.

Type material: Holotype: SMF 21.118 , specimen shown in Fig. 5C . Paratypes: SMF 21.117 , SMF 21.119 - SMF 21.125 .

Type locality: Üxheim-Ahütte , abandoned Müllertchen Quarry , Hillersheim Syncline , Eifel, western Rhenish Massif (UTM: 50°20’05.16’’N, 6°46’15.19’’E) .

Type horizon: Set 2 “Wurmweide”, Olifant Member, Müllert Subformation (Ahbach Formation, lowermost Lower Givetian, Middle Devonian; Polygnathus hemiansatus Conodont Biozone ).

Diagnosis.— Chaetosalpinx bioclaustrated by bryozoans

Stellatoides muellertchensis gen. et sp. nov.), cylindrical, averaging 0.7 mm in diameter, ranging from 0.4–1.3 mm, aperture circular, less commonly elliptical or reniform, edges raised slightly above surface of host bryozoan.

Description.—Cylindrical embedment trace (bioclaustration) found within colonies of cystoporate bryozoan Stellatoides muellertchensis gen. et sp. nov. Cylinder up to at least 4 mm long, oriented vertically (i.e., parallel to upward bryozoan growth direction) for most of length; straight, parallel sided, infilled either with calcite cement ( Fig. 5B ) or fine-grained sediment ( Fig. 5C ). No internal structures observed. Originating at or very close to the base of bryozoan colony, basal part of cylinder apparently horizontal in some examples. Cylinder bounded by wall formed by bryozoan skeleton (?interior wall calcification), up to 0.06 mm thick but usually about 0.03 mm thick, other bryozoan skeletal walls deflected upwards in vicinity of tube (cf. the downwards deflection of walls around autozooecial tubes); cystose skeleton often concentrically arranged around the tube when viewed in transverse section. Tube diameter ranging from 0.4–1.3 mm, averaging 0.7 mm. Numerous individuals of varying diameters opening on surface of same host bryozoan colony, locat- ed in intermacular areas, arranged semiregularly. Apertures circular, less commonly elliptical or reniform, edges raised by up to 0.3 mm above surrounding colony surface ( Fig. 5A ).

Remarks.—The new species fits within the concept of the ichnogenus Chaetosalpinx as applied by Stel (1976), Tapanila (2002, 2005, 2006), and Tapanila and Ekdale (2007) for tubular, vertical embedment traces with margins defined by skeletal walls secreted by biomineralized host organisms. Seven species of Chaetosalpinx have been described: the type species C. ferganensis Sokolov, 1948 , and its subjective synonyms C. khatangaensis Sokolov, 1948 , C. huismani Stel, 1976 and C. groningae Stel, 1976 (see Tapanila 2002, 2005), C. siberiensis Sokolov, 1948 , C. rex Tapanila, 2002 , and C. alamo Tapanila, 2006 . Tubes of C. siberiensis , C. rex , and C. alamo are conical, narrow basally, unlike the parallel-sided C. tapanilai ichnosp. nov. The diameter of C. tapanilai (0.4–1.3 mm) contrasts with the larger tubes of C. alamo (2.5–12.8 mm) and C. rex (up to 5 mm), whereas the smaller tubes of C. ferganensis range from 0.05–0.4 mm in diameter according to Tapanila (2002). Only C. siberiensis has a tube diameter (0.3–0.9 mm according to Stel 1976) overlapping that of C. tapanilai in diameter. However, as previously noted this species is conical and furthermore the tubes are described as being sinuous in longitudinal sections whereas those of C. tapanilai are straight.

Host symbionts for previously described species of Chaetosalpinx include rugose and tabulate corals ( Tapanila 2005: table 1) as well as stromatoporoid sponges ( Tapanila 2006). This Ordovician (Caradoc)–Devonian (Givetian) ichnogenus has not been described previously in bryozoans. Perhaps the closest similarity among bryozoans is with an un-named bioclaustration described from mid-Cretaceous cyclostomes ( Taylor and Voigt 2006). This has a similar diameter to C. tapanilai but is distinctly funnel shaped rather than cylindrical. Incipient tubular bioclaustrations are present in some Recent bryozoans growing around symbiotic spionid worms and tanaiid crustaceans (see below).

Figures

Fig. 5. Cylindrical embedment trace (bioclaustration) Chaetosalpinx tapanilai ichnosp. nov., Middle Devonian (Lower Givetian) of the Rhenish Massif, north-western Rhineland-Palatinate, Germany. A. Paratype SMF 21.115, colony surface of fistuliporid bryozoan Stellatoides muellertchensis gen. et sp. nov. showing tubes of C. tapanilai. B. Paratype SMF 21.122, tangential section of tubes of C. tapanilai. C. Holotype SMF 21.118, longitudinal section of a tube.