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 Author Cáceres-Chamizo, Julia P. Author Sanner, Joann Author Tilbrook, Kevin J. Author Ostrovsky, Andrew N. text Zootaxa 2017 4305 1 1 79 journal article 32505 10.11646/zootaxa.4305.1.1 24ae3650-4b27-4fcb-9f51-1787fd8aa2a4 1175-5326 842587 1192C3A0-5CCB-4A86-903C-A2B82906A5F9 Exechonella variperforata n. sp. ( Fig. 4 , Table 4 ) ? Exechonella tuberculata : Scholz & Cusi 1991 , p. 412, 428, pl. 4, fig. 1. Material examined. Holotype : MTQ G 100217 (mounted on SEM stub and coated with gold), on coral. Coral Sea , Great Barrier Reef , Lizard Island , Pigeon Point , depth 8–10 m , 9 October 2012 . Paratype : MTQ G 100218 , two fragments (mounted on SEM stub and coated with gold). Coral Sea , Great Barrier Reef , Lizard Island , Pigeon Point , depth 8–10 m , 9 October 2012 . Other material studied : MTQ G 100220 (mounted on SEM stub and coated with gold). CReefs Heron Island 2010. Coral Sea , Great Barrier Reef , Heron Island , Site HI 10-051, 23° 27’ 37.764’’ S , 151° 55’ 45.444’’ E , depth 16 m , 24 November 2010 , collected by K.J. Tilbrook , G. Cranitch. Etymology . The name was given because of the variations in shape and size of the frontal foramina in comparison with the other species of this complex. Derived from the Latin word “variis” (various). Description. Colonies encrusting, unilaminar, multiserial. Autozooids bottle-like: convex, oval-elongated, separated by deep grooves and pits in the ‘corners’ between zooids. Primary orifice oval, wider than long, anter wall underlain by an inner lamina (only visible in oblique view) ending in small rounded distolateral condyles. Long tubular peristome is pustulose externally and with longitudinal grooves on its internal surface, the rim is flared often with short pointed spikes. Frontal shield pustulose, with 8‒20 foramina of various shapes: from round and oval to irregular. In some zooids from one to six foramina bear the short triangular, blunt or pointed, process. Each process has mostly gymnocystal surface connected with vertical gymnocystal walls of its foramen. The area around a foramen is a slightly elevated narrow ring with an internal wall surface. Gymnocystal walls of neighbour lateralmost foramina often confluent with each other thus making the edge of frontal shield zigzag-like in outline. In this case the areas between foraminal luminae are closely apposed to the frontal shield of the neighbour zooid. The proximal part of the frontal shield is ‘reduced’ in some zooids making a sort of ‘gap’ in the ‘corner’ between zooids. 1‒2 rows of small, rounded marginal pores are seen mainly in the peripheral zooids. The distalmost part of zooid below peristome can be bear up to three rows of such pores. In the central part of the colony zooids are closely appressed and the marginal pores are not seen. No avicularia. Adventitious kenozooids with 2‒4 pores, each having cuticular plate. Vertical zooidal walls narrow or wide, represented by multiporous mural septula with communication pores arranged in two or several rows. Ancestrula unknown. TABLE 4. Measurements (in µm, except number of foramina) of the holotype specimen of Exechonella variperforata n. sp. Abbreviations: autozooid length (AzL), autozooid width (AzW), diameter of a foramen including rim (FoD), number of frontal foramina (FoN), diameter of the opening of a foramen (OD), primary orifice length (OrL), primary orifice width (OrW), peristome length (PeL), peristome width (PeW). Mean (m), standard deviation (sd), range (r) and number of measurements (n). Lizard Island, Great Barrier Reef Remarks. Exechonella variperforata n. sp. is characterized by its comparatively fewer foramina with narrow rim, by the irregular shape of some of them and by small rounded condyles.

m±sd	r	n
AzL	794±100	600–1000	26
AzW	536±53.3	433–650	26
OrL	154	143–164	2
OrW	226	210–233	2
FoN	15±2.5	8–20	27
FoD	80±13.2	50–109	45
OD	50±11.1	31–78	45
PeL	325±25	313–375	6
PeW	285±18.3	260–313	6

FIGURE 4. Exechonella variperforata n. sp. Great Barrier Reef, Lizard Island (A, B: holotype MTQ G100217; C‒F: paratype MTQ G100218). A, general view of the colony from above. Ancestrular zone is overgrown by calcareous algae. B, autozooid showing various foraminal shapes. C, general view of the colony fragment from above (‘gaps’ between zooids are clearly seen; peristome of left zooid bears two spikes). D, lateral view of the same fragment showing marginal pores arranged in 2‒3 rows and multiporous septula. E, primary orifice with condyles (arrows) visible. F, distolateral view of the frontal shield with foramina, two of which bear short pointed process. Scale bars: A = 1 mm; B‒ F = 100 µm. Most of the species of this complex are characterized by relatively high number of frontal foramina ( 16–41 in E. ampullacea , 13–45 in E. reniporosa n. sp. , 23–46 (Safaga) and 30–58 (Jeddah) in E. safagaensis n. sp. , and 13– 37 in E. maldiviensis n. sp . ) (see below). E. variperforata n. sp . is the only species with 8–20 foramina per zooid. The variability of the foraminal shape is rather prominent character of this species that is also met (though in lesser degree) in E. maldiviensis n. sp. Apart of our material from the Lizard Island, north part of the Great Barrier Reef, an additional colony of E. variperforata n. sp. has been collected at the Heron Island, south part of the Great Barrier Reef. Scholz and Cusi (1991) , described and illustrated a colony from Leyte, Philippines, identified as E. tuberculata , but it shows all the major characters of E. variperforata n. sp. , including shape of the peristome margin, and reduced number of foramina and their shape. Distribution. Despite of the above suspicions, the current distribution of E. variperforata n. sp. is restricted to the Great Barrier Reef.