Microporella browni, Harmelin, Jean-Georges, Ostrovsky, Andrew N., Cáceres-Chamizo, Julia P. & Sanner, Joann, 2011

Harmelin, Jean-Georges, Ostrovsky, Andrew N., Cáceres-Chamizo, Julia P. & Sanner, Joann, 2011, Bryodiversity in the tropics: taxonomy of Microporella species (Bryozoa, Cheilostomata) with personate maternal zooids from Indian Ocean, Red Sea and southeast Mediterranean, Zootaxa 2798, pp. 1-30 : 3-7

Microporella browni n. sp.

( Figs 1 A–G, 2A–E, Table 1 )

Material examined. Holotype: 2010-0001-0001 DPUV, on Haliotis mariae shell. South Oman, Salalah, near Mirbat, Kelp Bay, right side, 9 m, 16 January 2009. Paratypes: 2010-0001-0002 DPUV, 2010-0001-0003 DPUV, 2010-0001-0004 DPUV, 2010-0001-0005 DPUV, 2010-0001-0006 DPUV, 2010-0001-0007 DPUV, 2010-0001- 0 0 0 8 DPUV, on the same Haliotis mariae shell as the holotype. South Oman, Salalah, near Mirbat, Kelp Bay, right side, 9 m, 16 January 2009. Mounted on SEM stub: 2010-0001-0009 DPUV, 2010-0001-0010 DPUV, taken from bivalve shells. South Oman, Salalah, near Mirbat, Kelp Bay, right side, 9 m, 16 January 2009. Other material examined: M. browni n. sp. — Lebanon: Beirut, airport pier, 3–11 m, 2 colonies on serpulid tube, 25 September 2002; 4 colonies on shells, 16 July 2003. Indian Ocean: (1) Gulf of Aden, Tadjoura (1146’45 N, 4254’37’’ E), 20 m, 11 colonies beneath planar coral Pachyseris , October 1969; (2) South Oman, Salalah, near Mirbat, Kelp Bay, left side, 11 m, 5 colonies on bivalve shells, 23 January 2009; (3) Maldive Islands, North Male Atoll, Vabbinfaru Is., House Reef, 5–19 m, 4 colonies on bivalve shells, 12–13 January 2008; (4) Maldive Islands, North Male Atoll, Helengeli Is., March 1983, 4 colonies on bivalve shells, coll. F.F. Steininger. M. orientalis Harmer, 1957 — SEM photos of the holotype, NHM n 1986.2.1.2 (23.K1/2136) (courtesy of P.D. Taylor and S.F. Mawatari).

Etymology. Named in honour of the bryozoologist and geologist David A. Brown (1916–2009).

Description. Colony encrusting, unilaminar, small or medium-sized. Autozooids approximately pentagonal, hexagonal or oval, longer than broad (mean L/W = 1.32 in Lebanon, 1.28 in Oman and 1.35 in Maldives). Frontal shield moderately convex, entirely covered with small rounded nodes and small pseudopores intercalated between them (93–98 pores in Lebanon, 58–85 in Tadjoura, 70–95 in Oman, 31–51 in Maldives); areolae slit-like, oval or round, often poorly visible. Primary orifice wider than long, anter rounded, serrated with 11–19 denticles, these triangular with rounded summit, proximal border (poster) with an irregular, slightly corrugated edge between two low shoulder-shaped condyles at each corner, sometimes missing. Oral spines 4–5 in most cases, occasionally 3, 6 or 7, thin, often detached, sometimes particularly long (up to 600 µm) and curved outwardly in well-preserved zooids. Ascopore proximal to orifice at a distance equal to orifice length or shorter, surrounded by a rim, often more raised proximally, lumen C-shaped with median process relatively large, rounded, rectangular or triangular, both spinous, sometimes with anastomosed denticles forming bars. Avicularium normally single, on the right or left, proximolateral to ascopore, rostrum directed distolaterally, truncated with tapered tip, a little longer than the maximum width of the membranous proximal area, crossbar complete and robust, mandible setiform, thin, moderately long (0.5–0.8 Az L), with lower side gutter-shaped (when dry), bearing at a distance corresponding to rostrum tip 2 pointed lateral processes curved basally. Ovicells with no visible oral spines, personate, i.e. with tall, arched, granular collar, distally adjacent to ascopore, raised over orifice and distally joined to smooth, arched rim on proximal edge of ooecium to form a complete peristome. Entooecium globose, broader than long, coarsely granular, evenly ‘perforated’ with many ‘pseudopores’ a little smaller than those of frontal wall. Secondary orifice transversally oval and narrower than primary orifice. Ancestrula tatiform with 10 or 11 spines, with narrow cryptocyst, budding two distolateral autozooids. In youngest periancestrular zooids, denticles of primary orifice are poorly prominent, resembling small rounded knobs, spine number generally 6 or 7, up to 8 (in one zooid).

Remarks. All specimens of M. browni n. sp. from Lebanon, Tadjoura, Oman and Maldives are remarkably similar in features of the primary orifice, particularly the shape and distribution of the denticles on the distolateral edge, and the proximal edge slightly corrugated between low condyles. These condyles can be poorly or not prominent in the colonies from Oman and Maldives. The number of denticles observed in SEM photos indicates that this parameter may range differently according to locality: 12–16 in Lebanon (Beirut), 10–16 in the Gulf of Aden (Tadjoura), 13–18 in south Oman, 10–13 in the Maldives. For the whole suite of specimens, 13 is the modal number of denticles, which represents only 26% of the distribution. However, the tiny morphological traits of the orifice can be considered as highly diagnostic for this personate Microporella species. Zooids of M. browni n. sp. typically bear a single avicularium, lacking in some zooids including periancestrular ones. However, paired avicularia can be exceptionally present, as observed in two non-ovicellate (i.e. not associated with distal ooecium) zooids from two different colonies of the Tadjoura material. The colonies from Tadjoura also differ in their zooidal dimensions, which are larger than those of specimens from the other localities. These two particular features in the Tadjoura material may correspond to a local geographical morphotype. The southeastern Mediterranean specimens are similar in all morphological features to those collected in the Indian Ocean.

Microporella browni n. sp. strongly resembles M. orientalis Harmer, 1957 , originally described from Indonesia and commented on by Tilbrook (2006) after examing the holotype (NHM 1986.2.1.2) and studying one specimen from the Solomon Islands. According to Tilbrook (2006), M. orientalis is clearly characterized by orifices with a denticulate distal border and personate ovicells, i.e. with a raised proximal collar fused to the proximal edge of the entooecium. These features also characterise our specimens. However, comparison with unpublished SEM images of Harmer’s holotype (made by S.F. Mawatari) show clear differences in the mandible shape, which is setiform, thin, moderately long and pointed in M. browni n. sp., while it is short, more robust and hooked in M. orientalis . Specimens with personate ovicells from the area of Cochin ( India) ascribed to M. orientalis by Menon and Nandini Menon (2006, fig. 90) bear the same type of short and robust mandible. These authors also mentioned specimens ascribed to M. ciliata having orifices denticulated distolaterally. This identification is obviously not correct, but cannot be interpreted given the lack of SEM illustrations. Microporella browni n. sp. and M. orientalis also differ in the shape of the proximal edge of the zooidal orifice. The primary orifice of M. orientalis illustrated by Tilbrook (2006, pl. 45B) presents a proximal edge that is smooth and without condyles, while in our material it is normally uneven and presents a pair of low shoulder-shaped condyles.

The figures of M. monilifera Liu & Liu, 2003 (see also Liu et al. 2001) show that this species from the South China Sea is similar to Microporella browni n. sp. in several features, indicating a very close relationship. Both have ascopores bordered by a circular rim, single adventitious avicularia with similar shape, size, orientation and placement and, particularly, the primary orifices of non-ovicellate zooids are very similar in having a beaded distolateral border with similarly shaped denticles and a proximal edge presenting low condyles at the corners. In M. monilifera , however, the condyles are barely prominent and the proximal edge is smoother, the number of oral spines is only 3 vs 4–5 in M. browni n. sp., the ovicell is not described as personate and the figured one ( Liu et al. 2003, pl. II, fig. 3) has only lateral flaps that are abutted to the ooecium differently than the raised collar of M. browni n. sp.. Other differences are presented by the ooecium, which shows a flat, non-porous medioproximal area in M. monilifera while it is porous and edged by a proximal rim in M. browni n. sp., and by the ancestrula which is encircled with 18 spines in M. monilifera vs 10 or 11 in M. browni n. sp. Another difference is the mandible, described as "elongate triangular, without a horn at either side and with a flagelloid distal portion" ( Liu et al. 2001, p. 814).

Microporella browni n. sp. also strongly resembles M. maldiviensis n. sp., with which it shares the same type of personate ovicell, a single avicularium lateroproximal to the ascopore and orifices with the anter bearing denticles and poster slightly corrugated between two shoulder-shaped condyles. However, M. browni n. sp. differs from M. maldiviensis n. sp. in having denticles more prominent and the avicularium mandibles with a longer projection and not hooked at the tip.

The geographical distribution of M. browni n. sp. currently includes the Indian Ocean, with localities in the Oman Sea, the Gulf of Aden and Maldive Islands, and the Eastern Mediterranean.

Figures

FIGURE 1. M. browni n. sp., specimens from Oman, Indian Ocean (A-C: paratype 2010 - 0001 - 0009 DPUV; F: paratype 2010 - 0001 - 0009 DPUV). A: Distal half of a cleaned non-ovicellate zooid with five oral spines. B: Part of colony with a personate maternal zooid and ovicell and four zooids with initial stage of ovicell formation, two with a single avicularium and two without. C: Primary orifice with 4 oral spines, distal denticles, corrugated proximal edge and low condyles at the corners. D: uncleaned zooids with 5 or 6 oral spines, avicularium and setiform mandible folded over the frontal wall. E: gutter-shaped lower face of mandible bearing pointed processes near its basis. F: growing margin of a colony showing basal pore chambers. G: ancestrula and peri-ancestrular zooids. Scale bars: A, D, F = 100 µm; B, G = 200 µm; C, E = 50 µm.

Tables

TABLE 1. Morphometrics (in µm) of specimens of M. browni n. sp. from Lebanon, Tadjoura, Oman and Maldives. Length (L) and width (W) of autozooid (Az), ovicell (Ov), primary orifice (Or) and avicularium mandible (Md). Mean standard deviation, range and number of measurements (in brackets).

Lebanon	Tadjoura	Oman	Maldives
AzL 509.2 ±46.2	510.9 ±62.7	468.9± 40.9	413.0 ±42.7
- 415–605 (19)	390–615 (18)	410–550 (55)	340–520 (33)
AzW 383.6 ±45.4	363.4 ±50.7	367.5 ±39.7	307.3 ±39.9
- 320–510 (19)	300–485 (19)	300–470 (55)	230–380 (33)
OvL 211.5± 14.2	221.2 ±19.3	170.0± 30.2	194.7 ±15.9
- 185–230 (17)	195–250 (12)	140–210 (15)	170–230 (17)
OvW 249.4 ±17.1	248.8± 20.1	256.0± 25.3	230.0 ±10.6
- 220–290 (17)	220–280 (12)	230–300 (15)	220–260 (17)
OrL 78.1± 4.9	81.0± 4.3	71.9± 7.7	73.7 ±6.8
- 70–85 (21)	72–90 (18)	60–90 (55)	60–85(33)
OrW 108.8± 8.5	117.1± 4.4	96.5 ±12.0	93.3 ±9.6
- 80–108 (17)	110–125 (18)	80–130 (55)	80–110 (33)
MdL 218.6± 21.2	170.7 ±12.4	199.4 ±38.8	245.7± 7.9
- 185–240 (7)	150–190 (7)	150–277 (8)	240–260 (7)