Adeonellopsis toyoshioae, Hirose, 2016

Hirose, Masato, 2016, Diversity and distribution of adeonid bryozoans (Cheilostomata: Adeonidae) in Japanese waters, European Journal of Taxonomy 203 (203), pp. 1-41 : 26-29

Adeonellopsis toyoshioae sp. nov.

urn:lsid:zoobank.org:act:B7DA81C8-D492-4AEA-A953-CB19EDF8EF45

Fig. 16

Adeonellopsis subteres – Hayami 1971: 87, pl. 11, fig. 4.

Diagnosis

Colony dichotomously branching; branches flat, or nearly cylindrical, slender, roughly 0.7–1.4 mm wide. Autozooids oval, distinct, delineated by deep groove; with single row of small marginal pores. Frontal shield entirely with granules and wrinkles, forming thickened ridge around spiramen. Peristome raised, transversely broad. Spiramen large, equal to or greater than secondary orifice in size, variable in shape, divided into 4–8 stellate pores. Suboral avicularia triangular, large, distal to spiramen; directed distally or distolaterally, rostrum tip extending over proximal margin of orifice. Gonozooids unknown.

Etymology

The specific name refers to the T/V Toyoshio-maru of Hiroshima University.

Material examined

Holotype

JAPAN: small colony collected at Takatori, southwest of Otsuki , Kochi Prefecture, ~ 32°30' N, 132°50' E, by coral fishing net, 118–120 m depth, F/ V Yuryo-maru, 29 Sep. 2010 (NSMT-Te777).

Paratypes

JAPAN: small colony, same collection data as for holotype (NSMT-Te779); small branches of colony, north of Amami Oshima, 28°52'38.40" N, 129°33'13.80" E, 178 m depth, by biological dredge, T / V Toyoshio-maru, 24 May 2009 (NSMT-Te776); several branches of colony, collected at Oshima Shin-sone, 28°52'24.60" N, 129°33'5.40" E to 28°53'1.20" N, 129°33'5.40" E, 169–172 m depth, by biological dredge, T / V Toyoshio-maru, 24 May 2011 (NSMT-Te778); colony collected by NSMT, north of Hachijo-jima Island, 33°26'48.00" N, 139°42'42.00" E to 33°27'0.00" N, 139°42'24.00" E, 170– 176 m depth, RV Shinyo-maru, 21 Oct. 2003 (NSMT-TeS23); colony collected by NSMT, north of Hachijo-jima Island, 33°25'60.00" N, 139°41'54.00" E to 33°26’6.00” N, 139°41’36.00” E, 160–190 m depth, RV Shinyo-maru, 21 Oct. 2003 (NSMT-TeS24); several branches of colony, Oshima Shin-sone, 28°52.511' N, 129°33.233' E to 28°52.631' N, 129°33.313' E, 165–200 m depth, by biological dredge, T / V Toyoshio-maru, 29 May 2012 (NSMT-Te808); several branches of colony, north of Tanegashima Island, 30°53.317' N, 131°02.565' E to 30°53.336' N, 131°02.747' E, 165–200 m depth, by biological dredge, T / V Toyoshio-maru, 30 May 2012 (NSMT-Te802).

Measurements

Autozooids. ZL: 437̅624 (530±43); ZW: 224̅312 (255±20); n = 37. SOrL: 36̅76 (56±8); SOrW: 63̅102 (75±10); n = 28. SAvL: 91̅174 (136±19); SAvW: 52̅97 (72±9); n = 56. SpL: 62̅262 (114±46); SpW: 35̅116 (72±16); n = 61.

Additional small frontal avicularia. L: 83–119 (97±10); W: 37–62 (48±6); n = 13.

Description

Colony yellowish white, dichotomously branching, small, up to 3 cm high. Branches flat or nearly cylindrical, slender ( Fig. 16A ); 0.7–1.4 mm wide (average 1.0 mm, n = 15). Autozooids all around branches; oval, distinct, delineated by deep groove, with single row of small marginal pores ( Fig. 16B ). Frontal shield raised from margin, entirely textured with small granules and wrinkles, forming a thickened ridge around spiramen; ridge often bears up to four low, smooth umbos 40–78 μm in diameter (average 60 μm, n = 52) ( Fig. 16D ). Peristome raised, thick-walled distally and laterally, transversely broad; secondary orifice semicircular to transversely oval ( Fig. 16B, D ). Primary orifice hidden in peristome in frontal view. Spiramen large, size roughly equal to or greater than area of secondary orifice; variable in shape, divided into 4–8 stellate pores ( Fig. 16 D–E). Single large, triangular suboral avicularium between orifice and spiramen, directed distally or distolaterally ( Fig. 16B, E ); rostrum acute, tip often extending over proximal margin of orifice ( Fig. 16D ); mandible elongate-triangular; opesial opening oval; crossbar lacking. Some zooids have additional, smaller frontal avicularium budded, near proximal margin of zooid, pointing in any direction. Marginal vicarious avicularia triangular, directed distally; 312 μm long by 134 μm wide (n = 1). Gonozooids unknown.

Remarks

Adeonellopsis toyoshioae sp. nov. resembles A. subteres ( Römer, 1863) in the number of alternate zooidal rows, raised margin of the frontal shield, and a large ascopore occupying a broad area of the frontal shield ( Römer, 1863: pl. XXXV, fig. 6). However, A. subteres was originally reported as a fossil from Germany and occurs in the Eocene ( Canu 1907; Braga 1963) and Oligocene ( David & Pouyet 1968) deposits of Europe. I therefore concluded that A. toyoshioae sp. nov. represents a new species. Moreover, the Recent Adeonellopsis distoma ( Busk, 1858) from the eastern N Atlantic is closely related to both species; Adeonellopsis distoma resembles A. toyoshioae sp. nov. in having a subtubular peristome and a large area of multiporous spiramen consisting of about seven pores. Adeonellopsis distoma , however, differs from A. toyoshioae sp. nov. in having an elongated spiraminal area, with usually two rows of pores, in having larger suboral avicularia and fewer zooidal rows comprising the branches, and in lacking the marginal umbos. Adeonellopsis toyoshioae sp. nov. also resembles A. sparassis in having a multiporous ascopore with more than four denticulate pores, and a single suboral avicularium extending over the proximal margin of the orifice. However, the ascopore in A. toyoshioae sp. nov. is not circular as in A. sparassis and occupies a much larger area of the frontal shield. In addition, A. toyoshioae sp. nov. has branches less than 2.0 mm wide, whereas those in A. sparassis are usually wider than 2.5 mm. Finally, the suboral avicularium is often directed slightly distolaterally in A. toyoshioae sp. nov., whereas it points directly distally A. sparassis .

The marginal umbos evident on younger zooids in A. toyoshioae sp. nov. are identical in size to those in A. pentapora ; these umbos are also a characteristic feature of younger zooids in these species.

Distribution

Japanese Pacific waters: north of Hachijo-jima Island, southwest of Kochi Prefecture, and the northern Nansei Islands (near Amami Oshima and Tanegashima); at depths of 118– 200 m. Hayami (1971) reported this species from fossiliferous sandstone in the Pliocene Shinzato Tuff (Shinzato Formation) on Okinawa Island, which is close to the Recent distribution in Japan.

Figures

Fig. 16. Adeonellopsis toyoshioae sp. nov. A. Colonies from Amami Oshima (NSMT-Te776). B. Branch showing autozooids with broad multiporous spiramen (NSMT-Te776). C. Branch showing crenulate periphery, with tubular peristomes and acute avicularia (NSMT-Te776). D. Branch bifurcation lacking vicarious avicularia (NSMT-Te776). E. Distal end of branch showing young autozooids with large multiporous spiramen (NSMT-Te776). F. Old autozooids with immersed spiramen (NSMT-Te776). A = optical photograph; B–F = SEM images. Scale bars: A = 5 mm; B, E = 300 μm; C, F = 500 μm; D = 200 μm.