Schizomavella adriatica, Reverter-Gil & Souto & Novosel & Tilbrook, 2015

Reverter-Gil, Oscar, Souto, Javier, Novosel, Maja & Tilbrook, Kevin J., 2015, Adriatic species of Schizomavella (Bryozoa: Cheilostomata), Journal of Natural History 50, pp. 281-321 : 309-314

Schizomavella adriatica sp. nov.

( Figure 13 ; Table 12)

? Schizoporella auriculata: Hincks 1886: 270 .

? Schizomavella rudis: McKinney and Jaklin 2000: 13 , 14.

Schizomavella rudis: Hayward and McKinney 2002: 61 , fig. 27D – H; Novosel 2007: 65, fig. 28E – F.

Type material

Holotype. CNHM Inv. br. 43: St. 16, Korčula Island (Sika), 42°94.973 N, 17°16.026 E, 24 April 2004, 30 – 40 m depth, one colony on a bivalve shell ( Figure 13G ).

Paratypes. CNHM Inv. br. 44: St. 2, Ćutin Islet (Cres), 44°72.393 N, 14°49.374 E, 17 October 2001, 12 m depth, one colony on a stone .

CNHM Inv. br. 45: St. 2, Ćutin Islet (Cres), 44°72.393 N, 14°49.374 E, 17 October 2001, 12 m depth, three colonies on a piece of metal .

CNHM Inv. br. 46: St. 2, Ćutin Islet (Cres), 44°72.393 N, 14°49.374 E, 15 June 2000, 11 – 15 m depth, a colony on a shell .

CNHM Inv. br. 47 – 51: St. 16, Korčula Island , 42°94.973 N, 17°16.026 E, 24 April 2004, 15 – 20 m depth .

MNCN 25.03 /3919: St. 2, Ćutin Islet (Cres), 44°72.393 N, 14°49.374 E, 15 June 2000, 11 – 15 m depth, a free fragment .

MNCN 25.03 /3920: St. 16, Korčula Island , 42°94.973 N, 17°16.026 E, 24 April 2004, 15 – 20 m depth, one colony on a gastropod shell ( Figure 13A ) .

MNCN 25.03 /3921: St. 16, Korčula Island , 42°94.973 N, 17°16.026 E, 24 April 2004, 15 – 20 m depth ( Figure 13B, D, E, H ) .

NHMUK 2015.3.4.4: St. 2, Ćutin Islet (Cres), 44°72.393 N, 14°49.374 E, 17 October 2001, 12 m depth, one colony on a stone ( Figure 13C, F ) .

NHMUK 2015.3.4.5: St. 12, Vis (Komiža Bay), 43°04.430 N, 16°07.213 E, 1 September 2001, 12 m.

Other material examined

NHMUK 1899.5.1.459, NHMUK 1899.5.1.468, NHMUK 1899.5.1.989: Adriatic, Hincks coll. as Schizoporella auriculata ; reidentified by P. Hayward as Schizomavella sp. indet.

Diagnosis

Frontal shield uniformly perforated by rounded pores, each in a depression. Primary orifice rounded; sinus wide and shallow, flanked by two shoulders; condyles smooth. Suboral avicularium small, oval, distant from the primary orifice – that is, unattached to the rim – but frequently missing from large areas of the colony. Ovicell evenly perforated, soon covered by granular secondary calcification.

Etymology

Pertaining to its only known occurrence – that is, only found in the Adriatic Sea.

Description

Colony encrusting, multilaminar, forming large, irregular patches.

Autozooids distinct, separated by fine sutures, arranged in radial series in the basal layer, randomly orientated in frontally budded patches. Autozooids in the basal layer rectangular or polygonal in shape, irregularly polygonal in successive layers. Frontal shield flat or slightly convex, uniformly perforated by rounded pores, each in a distinct depression in newly formed individuals. In older zooids, the increase in secondary calcification gives the frontal wall a rough, granular appearance and the pores appear larger ( Figure 13B ); in heavily calcified zooids, the medial pores may become occluded, with the exception of the row of marginal pores which become elongate ( Figure 13A ). Zooid lateral walls with small uniporous septula, placed in rows near the basal wall.

Primary orifice rounded, nearly as long as wide. Proximal border with a wide, shallow sinus, occupying half of its width, flanked by two shoulders. Condyles smooth, moderately developed, extending from the edges of the sinus to the lateral edges of the orifice and continuous with it.

Suboral avicularium small, oval, slightly longer than wide, quite distant from the primary orifice and unattached to the rim. Proximally directed, with rostrum almost parallel to frontal plane. Crossbar complete, slender, sometimes forming an open angle in the middle but without columella. Opesia transversely oval or subcircular; palatal foramen large, oval, with semielliptical mandible. However, avicularia are frequently missing from large areas of a colony.

Ovicell acleithral, initially prominent, globose, evenly perforated by several circular pseudopores. Soon covered by granular secondary calcification, that may sporadically occlude the pseudopores.

Ancestrula unknown.

Remarks

Schizomavella adriatica sp. nov. was previously reported as Schizomavella rudis ( Manzoni, 1869) by Hayward and McKinney (2002) from the Northern Adriatic, by Novosel (2007) from several Croatian localities, and probably by McKinney and Jaklin (2000). Reverter-Gil et al. (2012) recently re-examined many Mediterranean records of S. rudis and as a result described a new species, Stephanotheca watersi . However, the record of Hayward and McKinney (2002) has been considered to correspond to another, as yet, undescribed species of Schizomavella . Among other differences with S. rudis , the zooidal orifice of S. adriatica sp. nov. has a proximal edge with a shallow sinus flanked by two shoulders and smooth condyles, the ovicell is uniformly perforated and is not closed by the operculum and S. adriatica sp. nov. does not exhibit a dimorphic orifice in ovicellate zooids.

Schizomavella adriatica sp. nov. shows some similarities with S. sarniensis and S. grandiporosa , as recently redescribed by Souto et al. (2013); for instance, it has the rounded orifice with a shallow, wide sinus, the frontal shield evenly perforated by large pores and the ovicell immersed by secondary calcification. However, the shape of the condyles is different amongst these three species: in S. adriatica sp. nov. they are smooth and continuous with the lateral walls of the orifice; in S. grandiporosa they are smooth, oval, with a lateral notch; and finally in S. sarniensis they are large, finely toothed and also notched. Differences are also seen in the avicularia amongst these three species. In S. adriatica sp. nov. the suboral avicularium is frequently absent from large areas of a colony, but when present it is distant from the primary orifice – that is, unattached to the orificial rim, with the rostrum parallel to frontal plane, the crossbar lacking a columella. In the other two species the avicularia are nearly always present, close to the sinus and continuous with the orificial rim, almost perpendicular to the frontal wall, and their crossbars have a well-developed columella.

Hincks (1886) reported the presence of S. auriculata in the Adriatic and defined the new variety S. auriculata var. spathulata . It is unclear if he considered all his Adriatic material to belong to this variety, or whether part of it represented the ‘ typical ’ morphology. We have examined three samples from the Adriatic in the Hincks collection (NHMUK 1899.5.1.459, NHMUK 1899.5.1.468, NHMUK 1899.5.1.989), originaly labeled as Schizoporella auriculata (later reassigned as Schizomavella sp. indet. by P. Hayward); this material is here assigned to S. adriatica sp. nov.

Other species previously reported from the Adriatic Sea

Schizomavella asymetrica ( Calvet, 1927)

Hayward and McKinney (2002) upgraded Calvet ’ s (1927) variety asymetrica to species status and reported it for the first time in the Adriatic. Schizomavella asymetrica was originally recorded from Monaco ( Calvet 1927) and subsequently reported by Gautier (1962) from Marseille and Tunis. Novosel ’ s (2007) record corresponds to S. stanislavi sp. nov. (see above). Schizomavella asymetrica was not found during the present study.

Schizomavella auriculata ( Hassall, 1842)

Several authors have reported S. auriculata from the northern and central Adriatic (see Novosel and Požar-Domac 2001; Novosel 2007). However, it must be stated that S. auriculata is an Atlantic species that is absent from the Mediterranean. Its diagnostic characters, previously confused with those of S. cuspidata (= S. cornuta ) as outlined above, were established by Hayward and Thorpe (1995). Previous records of S. auriculata in the Mediterranean correspond to various other species of Schizomavella , most often S. cornuta (see Reverter-Gil and Fernández-Pulpeiro 1996); however, the revision of all original material is necessary to validate the identifications.

Schizomavella discoidea ( Busk, 1859)

This species has previously been reported from the northern and central Adriatic ( Hincks 1887; McKinney 2000; McKinney and Jaklin 2000; Zavodnik et al. 2000; Novosel 2007). Lepralia discoidea was originally described from Madeira. Its type material was not found at the NHMUK, but we have examined Madeiran material in the Norman Collection. Comparison of this Madeiran material with European continental shelf records (from Great Britain to the Iberian Peninsula in the Atlantic, as well as the Western Mediterranean: see Hayward and Ryland 1999; López de la Cuadra and García-Gómez 2001; Reverter-Gil and Fernández-Pulpeiro 2001), strongly suggests that these records actually correspond to at least one new undescribed species, but a thorough revision of the material will be necessary to elucidate this any further. Notwithstanding, S. discoidea s. l. and S. halimedae (found during the present study) are morphologically similar species that have only recently been clearly separated (see López de la Cuadra and García-Gómez 2001). As stated by these authors, many previous records of S. discoidea s. l. in the Mediterranean are probably referable to S. halimedae , a species restricted to the inner Mediterranean. In fact Hincks (1887, p. 303), who first reported S. discoidea from the Adriatic, stated that ‘ In specimens from the Adriatic the small avicularium on the front of the cell is sometimes replaced by a long spatulate form. The dependent lateral appendages were not noticed ’. This description clearly corresponds to S. halimedae . However, S. discoidea , or another very similar undescribed species, seems to be present at least in the western Mediterranean. Therefore, the presence of S. discoidea in the Adriatic cannot be discounted, but needs further investigation to be confirmed. No colonies of S. discoidea were found during the present study.

Schizomavella gautieri Reverter-Gil and Fernández-Pulpeiro, 1997

This species was originally described from Algeria, and later found in Isola Vulcano ( Italy) (J.-G. Harmelin unpublished data: MNHN 20204). It was wrongly reported from the Adriatic by Novosel (2007); her original material has been re-examined and belongs to S. cornuta (see above). Schizomavella gautieri was not found during the present study.

Schizomavella hastata ( Hincks, 1862)

This species was previously reported in the Adriatic by Brusina (1907), Friedl (1918), and Novosel (2007). However, the specific characters of this species were unclear until its redescription by Hayward and Thorpe (1995). Material documented by Novosel (2007) is here reassigned to S. linearis (see above). It should be stressed that the most useful character for distinguishing S. hastata from other species of Schizomavella is the shape of the primary orifice, not the size and position of the suboral avicularium. In a reexamination of reference illustrations and material assigned to S. hastata from the Mediterranean, we have noticed that many orifices actually resemble those of S. linearis rather than S. hastata – that is, they never show the characteristic shallowly concave proximal border seen in S. hastata . In conclusion, S. hastata is probably absent from the Adriatic, and perhaps from the whole Mediterranean, although it was previously considered to be present in the area ( Reverter-Gil and Fernández-Pulpeiro 1996; Hayward and Ryland 1999). All previous records will need to be reassessed with reference to their original material to ascertain its true distribution.

Schizomavella ochracea ( Hincks, 1862)

This species was erroneously cited by Novosel and Požar-Domac (2001) when compiling previous records from the Adriatic. Friedl (1918) actually cited ‘ Smittina auriculata var. spathulata ( Hincks, 1886 = var. ochracea Hincks ) ’ from near Banjol (Rovinj), around Brijuni islands and near Muggia ( Italy); subsequently, Vatova (1928) compiled this record. The variety spathulata actually corresponds to S. cornuta (see above). Lepralia ochracea has been redescribed recently and reassigned to the genus Stephanotheca . Irrespective of this, it seems to be absent from the Mediterranean anyway (Reverter- Gil et al. 2012).

Schizomavella rudis ( Manzoni, 1869)

This species was reported in the Adriatic by McKinney and Jaklin (2000), Hayward and McKinney (2002) and Novosel (2007). As stated above, all of these records probably correspond to S. adriatica sp. nov.

Schizomavella subsolana Hayward and McKinney, 2002

This species, described by Hayward and McKinney (2002) from the northern Adriatic, was later reported by Novosel (2007). Unfortunately, her original material has been lost, and so was not included in the present study.

Schizomavella triangularis Reverter-Gil and Fernández-Pulpeiro, 1997

This species was reported by Chimenz Gusso et al. (2007) from the northern Adriatic, but it was a typographical mistake (Chimenz Gusso pers. comm.); it was deleted from that area in a subsequent paper ( Rosso et al. 2010). Schizomavella triangularis was not found during the present study.

Figures

Figure 13. Schizomavella adriatica sp. nov. (A, B) Groups of zooids with variably calcified frontal wall (A MNCN 25.03/3920, paratype, St. 16, Korčula Island; B MNCN 25.03/3921, paratype, St. 16, Korčula Island); (C, D) primary orifices (C NHMUK 2015.3.4.4, paratype, St. 2, Ćutin Islet; D MNCN 25.03/3921, paratype, St. 16, Korčula Island); (E) suboral avicularium with crossbar forming an open angle (MNCN 25.03/3921, paratype, St. 16, Korčula Island); (F) developing ovicells, from initial stage (up) to completely covered with secondary calcification (down; NHMUK 2015.3.4.4, paratype, St. 2, Ćutin Islet); (G) group of ovicellate zooids (CNHM Inv. br. 43, holotype, St. 16, Korčula Island); (H) group of ovicellate zooids (MNCN 25.03/3921, paratype, St. 16, Korčula Island).

Tables

Table 12. Measurements (in mm) of Schizomavella adriatica sp. nov. (paratypes, Korčula Island and Ćutin Islet).

	Mean	SD	Minimum	Maximum	N
Autozooid length	0.458	0.0439	0.360	0.590	32
Autozooid width	0.369	0.0551	0.217	0.488	32
Orifice length	0.106	0.0096	0.090	0.127	32
Orifice width	0.117	0.0118	0.089	0.137	32
Ovicell length	0.210	0.0227	0.179	0.266	26
Ovicell width	0.266	0.0268	0.203	0.307	26
Avicularium length	0.069	0.0081	0.057	0.087	25
Avicularium width	0.052	0.0061	0.038	0.063	25

Note: SD, standard deviation; N, number of measurements.