Microporella modesta Di Martino, Taylor & Gordon, 2020

Martino, Emanuela Di & Rosso, Antonietta, 2021, Seek and ye shall find: new species and new records of Microporella (Bryozoa, Cheilostomatida) in the Mediterranean, ZooKeys 1053, pp. 1-42 : 1

Microporella modesta Di Martino, Taylor & Gordon, 2020

Fig. 7

Microporella modesta Di Martino et al. 2020a: 23, fig. 11, table 8.

Microporella orientalis Harmer, 1957: Rosso 1996a: table 2.

Microporella ciliata (Pallas): Rosso 1989: tables 3, 4, 6; Di Geronimo et al. 1990: table 1; Di Geronimo et al. 1993b: table 3; Rosso 1996a: table 2; Rosso 1996b: table 1; Hayward and McKinney 2002: 83, fig. 37e-j.

Microporella cf. ciliata (Pallas): Chimenz Gusso et al. 2014: 189, fig. 101a-f.

Microporella gr. ciliata (Pallas): Rosso et al. 2019a: table 1.

Examined material.

Italy • 30 dead colony fragments, 8 of which bilaminar, 1 pseudovinculariform and the majority encrusting on Cellaria internodes; Ionian Sea, E Sicily, Ciclopi Islands MPA; Ciclopi 2000 cruise; sample 2G, 8I, 9G, 12E, 12F, 12G; 37°34'4"N, 15°10'51"E; 63-95 m; Jul. 2000; DC, DE-DL, DL Biocoenoses; A. Rosso leg.; dredging; PMC Rosso-Collection I. H. B. 86a . Italy • 1 living colony, Ionian Sea, E Sicily, Ciclopi Islands MPA; sample SM1Z25; 37°38'17"N, 15°10'53"E; 25 m; Jun. 2015; R. Leonardi leg.; scuba diving; IA Biocoenosis; PMC Rosso-Collection I. H. B. 86a1 . Italy • 2 living colonies fouling on a plastic bag; Ionian Sea, E Sicily, Gulf of Ognina, North of Catania ; 37°31'52"N, 15°6'59"E; 4 m; 11 Feb. 2012; V. Grado leg.; scuba diving; PMC Rosso-Collection I. H. B. 86b . Italy • 15 living colonies on Posidonia leaves; Ionian Sea, E Sicily, S of the Gulf of Catania, Castelluccio ; 37°18'32"N, 15°7'59"E; beached; 6 Feb. 2019; A. Rosso leg.; hand-collected; PMC Rosso-Collection I. H. B. 86c . Italy • 3 living and 1 dead colony fragments; Ionian Sea, SE Sicily, Plemmirio MPA, Granchi submarine cave; sample GR1; 37°00'18"N, 15°18'35"E; 23 m; 14 Sep. 2009; V. Di Martino leg.; scuba diving; C and GSO Biocoenoses; PMC Rosso-Collection I. H. B. 86d . Italy • 16 living and 32 dead colony fragments, nearly all on Cellaria internodes, Ionian Sea, SE Sicily, Gulf of Noto ; 36°41'45"- 36°57'47"N, 15°8'35"- 15°20'00"E; PS/81 cruise; samples CR1, 2XB, 4C, 4X, 9B, 9C, 9D, 10C, 11E; 45 m (living), 44-120 m (dead); I. Di Geronimo leg.; dredging; and 25 living and 25 dead colony fragments, nearly all on Cellaria internodes; Noto 1996 cruise; samples 3C, 5E, 7E, 10G, 10I, WP120; 20-82 m (living), 90-107 m (dead); 1996; E. Mollica leg.; dredging; C, DC, DE and DL Biocoenoses; PMC Rosso-Collection I. H. B. 86e . Italy • 2 living colonies, Ionian Sea, Gulf of Taranto, Amendolara Bank ; samples 1D and 5D; 39°51'42"- 39°52'54"N, 16°42'00"- 16°43'24"E; 30-40 m; Jun. 1991; R. Sanfilippo leg.; dredging; DC Biocoenosis; PMC Rosso-Collection I. H. B. 86f. Italy • 4 living and 3 dead colonies; Sicily Strait, Pelagie Islands MPA, Lampedusa Island ; submarine caves: Taccio Vecchio I, 35°31'29"N, 12°35'58"E, 20 m; Grotta della Madonna , 35°30'2"N, 12°33'25"E, 15 m; Grotta dello Scoglio di Fora , 35°30'25"N, 12°33'33"E, 10 m; Jun. 2009; V. Di Martino leg.; scuba diving; C and GSO Biocoenoses; PMC Rosso-Collection I. H. B. 86g . Italy • about 100 living colonies, mostly on Posidonia leaves, soft algae, light calcified Peissonnelia spp. and calcified thin-branched geniculate corallines; Sicily Strait, Egadi Islands, Marettimo Island ; sample ECE5; 37°56'59"N, 12°3'56"E; 8 m; summer 2007; A. Sinagra leg.; IA and HP Biocoenoses; scuba diving; PMC Rosso-Collection I. H. B. 86h . Italy • 6 living and 2 dead colony fragments, 2 of which bilaminar; southern Tyrrhenian Sea, SW Ustica, Apollo Bank ; 38°42'19"N, 13°7'58"E; 60 m; Jun. 1986, dredging and scuba diving; Laminaria rodriguezii Bornet, 1888 seagrass and associated DC; PMC Rosso-Collection I. H. B. 86i . Italy • 7 living colonies; Iberian-Provençal Basin, Asinara MPA; samples PSE and PSI1; 41°6'59"N, 8°18'6"E; 5-15 m; A. Sinagra leg.; scuba diving; IA Biocoenosis; PMC Rosso-Collection I. H. B. 86j . Italy • 1 dead colony, southern Adriatic Sea, off Apulia, Bari canyon; sample 1B1; 41°17'29"N, 17°9'14"E; 280 m; 29 May 2012; F. Mastrototaro leg.; dredging; PMC Rosso-Collection I. H. B. 86k .

Remarks.

Microporella modesta has been recently established ( Di Martino et al. 2020a) for some Mediterranean specimens collected off Algeria and growing as erect, narrow, bilaminar fronds. However, SEM images in Hayward and McKinney (2002) and Chimenz Gusso et al. (2014) reveal that a large part of the figured Mediterranean specimens seem to be conspecific with M. modesta , although none of them has been described as erect bilaminar. This is also the case for most colonies and colony fragments in the collection of one us (AR), mostly previously assigned to M. ciliata , which allowed us to assess the intraspecific variability of M. modesta .

Strap-like branches including up to 11 or 12 longitudinal series of zooids occur only occasionally (Fig. 7A ), while bilaminar arched fronds narrowing proximally are rare, and encrusting sheets are the most common. Branches are always broken off so that the way they form from the putative encrusting base remains unknown. Lateral edges often consist of extremely elongate autozooids covering the length of three regular autozooids, with the proximal two thirds about half the width of the distal part (Fig. 7A ). Apparently cylindrical branches result from colonies encrusting thin, cylindrical substrata (Fig. 7B, E ), either mineralised and persistent (mostly internodes of Cellaria in deep-water samples, and geniculate coralline algae in shallow-water samples), or organic and ephemeral. In this latter case, the resulting pseudovinculariiform colonies are found in the sediment as hollow tubular fragments after substratum decay. A great number of colonies were observed encrusting soft algae, small Peissonnelia spp., and leaves of Posidonia oceanica (Linnaeus) Delile 1813, usually developing relatively small colonies, occasionally reaching 1-2 cm2.

In addition to colony morphology, variability includes also autozooidal characters. The orificial condyles were less prominent and more laterally placed in specimens from the Apollo Bank; the number of spines is usually five in encrusting colonies from the Ionian Sea (e.g., Amendolara and Ognina), but up to six or seven on some autozooids in colonies from the Sicily Strait (e.g., Madonna cave); spines also tend to be thicker, and the proximal pair more visible on ovicellate autozooids (e.g., in colonies from caves of the Ionian Sea and Sicily Strait) than in the holotype; a prominent central umbo can develop on the ovicell of some zooids (Fig. 7C, D ). As in Microporella ichnusae sp. nov., irregularly shaped elongated autozooids develop when lobes of a colony join, mostly in colonies on cylindrical substrata (Fig. 7B ). Intrazooidal budding frequently occurs in avicularia, while repair of autozooids was rarely observed.

The ancestrula was observed for the first time only in two colonies (sample PSI1 and ECE5), seemingly because it is soon overgrown. It is tatiform, with 10-12 spines surrounding a very thin, raised rim without apparent cryptocyst. It is rebudded as a kenozooid with a row of at least eight pores in one case (Fig. 7F ). A comparable structure was figured in Kukliński and Taylor (2008) for M. ciliata and can be also observed in M. browni from the Maldive Islands (https://www.univie.ac.at/Palaeontologie/Sammlung/Bryozoa/Maldive_Islands/Cheilostomata/Microporellidae/Microporella/Microporella-browni.html). The ancestrula buds two distolateral autozooids with 5-7 oral spines.

Ovicells are very numerous in this species, occurring in the majority of autozooids in some colonies (Fig. 7A, C, E ). Ovicell tubercles when developed, along with the mucro associated to the ascopore, and the raised rostrum of the avicularium give to the colony a characteristic knobby or spiky appearance.

The majority of specimens recorded from the Mediterranean previously assigned to M. ciliata , as well as some isolated colony fragments attributed to M. orientalis seem to belong to M. modesta .

Distribution and ecology.

Microporella modesta was previously reported exclusively from off Algeria ( Di Martino et al. 2020a), but the material studied here as well as specimens figured in recent literature ( Hayward and McKinney 2002; Chimenz Gusso et al. 2014) widen its geographical distribution. The species appears to be widely distributed in the Mediterranean where it occurs in the Iberian-Provençal basin, the Tyrrhenian, Ionian, and Adriatic seas as well as in the Sicily Strait. The species seems widely distributed in shallow shelf habitats with preference for the vegetate bottoms of the infralittoral zone and the Coralligenous Biocoenosis, with the possibility to extend into semi-dark caves. Findings from deeper (mid-shelf) particulate bottoms are largely represented by dead colonies/fragments possibly indicating a displacement.

Figures

Figure 7. Microporella modesta Di Martino, Taylor & Gordon, 2020 from several localities A Ionian Sea, Ciclopi 2000, PMC Rosso-Collection I. H. B. 86 a B Ionian Sea, Gulf of Noto, PMC Rosso-Collection I. H. B. 86 e C Sicily Strait, Egadi Islands, PMC Rosso-Collection I. H. B. 86 h D Ionian Sea, Castelluccio, PMC Rosso-Collection I. H. B. 86 c F Iberian-Provencal Basin, Asinara MPA, PMC Rosso-Collection I. H. B. 86 j A bilaminar branch with elongate autozooids along branch edge and a cluster of ovicells B apparently cylindrical branch resulting from a colony encrusting an internode of Cellaria. Note the formation of irregularly elongate autozooids C unbleached colony encrusting a soft algal frond. Prominent avicularian rostra and mucros associated with ascopore contribute to the spiky appearance of the colony. Note the co-occurrence of ovicells with and without frontal tubercles D bleached colony on algae with ovicells with different degrees of frontal tubercle development E ovicellate zooids of a tubular " pseudovinculariiform " colony originally developed on a thin ephemeral substratum F originally tatiform ancestrula regenerated as a kenozooid, budding two distolateral autozooids lacking avicularia. Scale bars: 1 mm (A); 200 µm (B, E, F); 500 µm (C, D).