Exechonella erinacea ( Canu & Bassler, 1929 )

Cáceres-Chamizo, Julia P., Sanner, Joann, Tilbrook, Kevin J. & Ostrovsky, Andrew N., 2017, Revision of the Recent species of Exechonella Canu & Bassler in Duvergier, 1924 and Actisecos Canu & Bassler, 1927 (Bryozoa, Cheilostomata): systematics, biogeography and evolutionary trends in skeletal morphology, Zootaxa 4305 (1), pp. 1-79 : 10-11

Exechonella erinacea ( Canu & Bassler, 1929)

( Fig. 2 , Table 2)

Coleopora erinacea: Canu & Bassler 1929 , p. 268–269, pl. 19, figs 5–8.

Material examined. Lectotype: USNM 7967 , encrusting on shell. Philippines, Jolo Island , Jolo Light, 6o 4´25´´N, 120o 58´30´´E, Albatross Station D. 5137, depth 20 fathoms, 14 Febuary 1908.

Description. Colonies encrusting, unilaminar, multiserial. Autozooids convex, oval, separated by grooves. Very narrow gymnocystal rim is seen between some zooids. Primary orifice oval, wider than long, anter wall underlain by an inner lamina (only visible in oblique view) ending in distolateral triangular condyles with their tips directed to the orifice midline. Long and tubular peristome is pustulose externally. Frontal shield pustulose, with 32–46 rounded or oval foramina. Lumen of each foramen has vertical, wide gymnocystal walls, whereas an area around is a slightly elevated, wide ring with an inner wall surface. In old zooids foramina distally or distolaterally bear a large thick spike-like process. Marginal pores small and rounded, predominantly visible in the distal part of zooid. No avicularia. Adventitious kenozooids of various shapes are seen between autozooids; with 2‒6 pores, each having centrally perforated cuticular plate. Vertical zooidal walls narrow, represented by multiporous mural septula with communication pores arranged in two rows. Ancestrula is unknown.

Remarks. Although E. erinacea was described by Canu and Bassler (1929) as Coleopora , it was suggested later that this species belongs to Exechonella ( Cook & Bock 2004) . It is characterized by the presence of its large thick spike-like process associated with foramina, and its closest relative is E. tuberculata ( MacGillivray, 1883) whose holotype and additional specimens were examined and figured by Cook and Bock (2004) (see above). Although both species show similar foramina structures and large zooids (approximately 1 mm in length), there are a number of differences between them as follows: (1) E. erinacea has a bigger range of the foramina number, 32– 46, whereas it is 16–27 in E. tuberculata ; (2) frontal shield is less prominent and swollen in E. erinacea which makes marginal pores visible, the condition that is absent in E. tuberculata ; (3) there is very narrow gymnocystal rim between zooids in E. erinacea , and it is absent in E. tuberculata ; (4) foraminal processes are pointed in the former species and blunt in the latter; (5) finally, a presence of kenozooids with 2–6 pores is recorded in E. erinacea and not in E. tuberculata .

Philippines

m±sd r n AzL 938.4±60.8 861–1055 7 AzW 754.1±100.3 639–917 7 OrL 190±7.8 181–195 3 OrW 245.3±16.7 236–264 3 FoN 41±4.8 32–46 8 FoD 48.6±7.28 42–61 21 OD 94.19±7.4 79–109 21 Specimen USNM 7967 was mentioned among two cotypes of E. erinacea (as Coleopora ) by Canu and Bassler (1929). We selected it as lectotype. Our check of the second specimen (USNM 7968) showed it does not belong to Exechonella .

Harmer (1957, pl. 54, figs 13, 14) figured two specimens from the New Guinea as E. tuberculata (see also above). One of them is more similar to E. erinacea because the foramina number exceeds 30 and the frontal processes are pointed. Its restudy is required before more definite conclusion can be made. Distribution. The present species is found near the Philippines.

Figures

FIGURE 2. Exechonella erinacea (Canu & Bassler, 1929). Philippines, Jolo Island (A ‒ D: lectotype USNM 7967). A, B, general view of the colony from above. C, three autozooids showing opercula and a shape of the primary orifice. Kenozooids with pores pointed by arrows. D, close-up of two zooids showing the shape of foraminal luminae and a condyle (arrowhead). Scale bars: A, B = 500 µm; C, D = 200 µm.