Schizomavella stanislavi, 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 : 300-303

Schizomavella stanislavi sp. nov.

( Figure 9 ; Table 7)

Schizomavella asymetrica: Novosel 2007: 61 , fig. 26 A, B.

Schizomavella auriculata: Novosel 2007: 62 , fig. 26C, D.

Schizomavella cornuta: Novosel 2007: 62 , fig. 26 E (in part).

Type material

Holotype. CNHM Inv. br. 38: St. 8: Jabuka Shoal (PJ-1), 43°06.060 N, 15°26.210 E, 27 August 2001, 13 m, a colony on alga ( Figure 9D, F ).

Paratypes. CNHM Inv . br. 39: St. 8, Jabuka Shoal (PJ-1), 43°06.060 N, 15°26.210 E, 27 August 2001, 10 m.

CNHM Inv. br. 40: St. 8, Jabuka Shoal (PJ-1), 43°06.060 N, 15°26.210 E, 27 August 2001, 20 m .

CNHM Inv. br. 41: St. 8, Jabuka Shoal (PJ-3), 43°06.060 N, 15°26.210 E, 28 August 2001, 10 – 15 m depth, a small colony.

CNHM Inv. br. 42: St. 9, Jabuka Islet (J4), 43°05.500 N, 15°27.600 E, 29 August 2001, 20 – 25 m.

MNCN 25.03 /3907: St . 8, Jabuka Shoal (PJ-1), 43°06.060 N, 15°26.210 E, 27 August 2001, 13 m depth, several fragments on alga.

MNCN 25.03 /3908: St . 8, Jabuka Shoal (PJ-3), 43°06.060 N, 15°26.210 E, 28 August 2001, 10 – 15 m depth, a small colony, on alga.

MNCN 25.03/3909: St. 15, Lastovo Island (Struga), 42°72.378 N, 16°88.429 E, 07 March 2002, 20 – 35 m, some colonies on alga and one on Reteporella sp. ( Figure 9A, E ).

NHMUK 2015.3.4.2: St. 8, Jabuka Shoal (PJ-1), 43°06.060 N, 15°26.210 E, 27 August 2001, 10 m, some small free fragments.

NHMUK 2015.3.4.3: St. 9, Jabuka Islet (J4), 43°05.500 N, 15°27.600 E, 29 August 2001, 5 – 10 m, several small free fragments ( Figure 9B, C ).

Other material examined

Schizomavella hirsuta ( Calvet, 1927) n. comb.

MOM 421601 : Holotype of Schizoporella auriculata var. hirsuta Calvet, 1927 (by monotypy).

Diagnosis

Primary orifice rounded, without proximolateral notches; sinus small, quadrate or U-shaped, occupying one third of the proximal border; condyles small, inconspicuous; primary orifice surrounded by an even rim, including the suboral avicularium; three or four long and thick distal spines; avicularium median suboral, subrectangular; distalmost part of the avicularium (the opesia) covered by a raised, calcified opesial ‘ hood ’; rostral palate foramen triangular; frontal wall with minute processes between the pseudopores; ovicell prominent, rapidly covered by secondary calcification, becoming similar in appearance to the frontal shield – that is, covered in pores and minute processes.

Etymology

Named in honour of the senior author ’ s father, Estanislao Reverter Sequeiros.

Description

Colony encrusting, unilaminar, developing small, irregular, subcircular crusts. Autozooids rectangular to polygonal, in linear series, separated by fine ridges.

Frontal shield nodular, evenly perforated by round pseudopores, plus a row of conspicuous areolar pores; a single smaller pore on each side of the suboral avicularium. In young zooids the frontal wall is convex; in older zooids the frontal wall calcification increases until it reaches the same level as the top of the peristome and produces minute pointed processes between the pores, while the pores themselves become deeply immersed and larger.

Primary orifice rounded or somewhat quadrate, deeply immersed in well-calcified zooids; slightly wider than long; small median sinus, quadrate or U-shaped, occupying one third of the proximal border, concealed by the suboral avicularium, often difficult to see in frontal view; condyles small, inconspicuous, with a smooth, straight distal edge and rounded end, just reaching the edge of the sinus; proximolateral notches absent or poorly marked. Primary orifice surrounded proximally and laterally by a fine, even rim, into which the suboral avicularium is incorporated.

Three or four, or even five, distal spines, hollow, long and thick, but frequently broken; their bases are present underneath the ovicell along the distal orifice margin.

Zooid lateral walls with small, uniporous septula, placed in rows near the basal wall.

Avicularium median, suboral, monomorphic, placed within the oral rim and nearly perpendicular to the frontal wall; rostrum subrectangular, directed frontally; complete crossbar with a small, median columella; distalmost part of the avicularium (the opesia) covered by a raised calcified opesial ‘ hood ’ which may conceal the orificial sinus; palatal foramen triangular, with inner edges slightly denticulate.

Ovicell acleithral, prominent, recumbent on the frontal wall of the succeeding zooid, broader than long; surface with several scattered circular ectooecial pseudopores, smaller than those in the frontal shield; rapidly covered by secondary calcification, becoming similar to the frontal shield, with small processes between scattered pores, but with a small, smooth, vertical area, just distal to the primary orifice.

Ancestrula unknown.

Remarks

Some European species of Schizomavella also develop a frontal wall covered by pointed processes, especially around the orifice, for instance: the Atlantic species S. sarniensis Hayward and Thorpe, 1995 and S. teresae , the Atlanto-Mediterranean S. grandiporosa Canu and Bassler, 1925 and the Mediterranean Schizoporella auriculata var. hirsuta Calvet, 1927 .

Schizomavella sarniensis differs from S. stanislavi sp. nov. in having larger condyles with finely toothed distal edges, a less-developed orificial rim that just touches the suboral avicularium but does not include it, and the larger avicularium without the distal calcified ‘ hood ’, which is occasionally enlarged and occupying most of the frontal wall.

Schizomavella teresae differs from S. stanislavi sp. nov. in the shape of the primary orifice, with its almost drop-shaped outline and narrower proximal edge, its broad condyles with pointed corners projecting above the sinus, and its smaller avicularium, without a palate or distal calcified ‘ hood ’, that does not project above the peristome.

Schizomavella grandiporosa , as recently redescribed by Souto et al. (2013), differs from S. stanislavi sp. nov. in having a wider and shallower sinus, a less developed orificial rim, which is in contact with the shorter suboral avicularium but not engulfing it, and the distinct larger pores in the frontal wall.

Calvet (1927) described Schizoporella auriculata var. hirsuta based on a single colony from Monaco, characterising it based on the development of frontal calcification covered by minute pointed processes on both the autozooids and ovicells. We have revised the holotype of this variety ( MOM 421601 , Figure 10 ), and believe it should be upgraded to species level as Schizomavella hirsuta . This species differs from S. stanislavi sp. nov. mainly due to the primary orifice, with its straight lateral borders, the distinct shoulders on each side of the sinus and the larger condyles producing lateral notches ( Figure 10 B, C ). Other differences include a suboral avicularium which projects well above the frontal surface on a somewhat quadrangular prominence (the distal calcified ‘ hood ’ of the avicularium is frequently asymmetrical; see Figure 10D ), and the heavily developed process-covered peristome that conceals the primary orifice; in S. stanislavi sp. nov. the primary orifice is always clearly seen.

However, it must be noted that all four of these species may appear quite similar when studied using only binocular microscope; a clear differentiation is only made possible by using an SEM on thoroughly cleaned material.

The primary orifices of S. stanislavi sp. nov. and S. tubulata sp. nov. are similar in the absence of proximal notches but S. tubulata sp. nov. differs in the stout oral spines forming an arch, and its stouter condyles. Moreover, the peristome in S. tubulata sp. nov. is more highly developed, forming a tube, and its ovicell is also different from that of S. stanislavi sp. nov.

Figures

Figure 9. Schizomavella stanislavi sp. nov. (A) Part of a lightly calcified colony (MNCN 25.03/3909, paratype, St. 15, Lastovo Island); (B, C) heavely calcified colony, showing frontal wall, with pointed processes, reaching the same level as the peristome (NHMUK 2015.3.4.3, paratype, St. 9, Jabuka Islet); (D) primary orifices (CNHM Inv. br. 38, holotype, St. 8, Jabuka Shoal); (E) ovicellate zooids (MNCN 25.03/3909, paratype, St. 15, Lastovo Island); (F) ovicellate zooids (CNHM Inv. br. 38, holotype, St. 8, Jabuka Shoal).

Figure 10. Schizomavella hirsuta (holotype: MOM 421601). (A) Growing edge of the colony showing developed suboral avicularia; (B, C) primary orifices; (D) development of the oral spikes concealing the primary orifices; note the asymetrical avicularian calcified ‘hood’.