New Recent foraminiferal genera and species from the lagoon at Madang, Papua New Guinea

Two new genera and eight new species of benthic foraminifera are described from the shallow water, tropical lagoon of Madang, Papua New Guinea. The new hauerinid genus Pseudolachlanella is characterized by juvenile cryptoquinqueloculine, adult almost massiline arranged chambers, and a slitlike, curved aperture with parallel sides and a long, slender, curved miliolid tooth. Pitella haigi n. gen., n. sp. is a new foraminifera with cryptoquinqueloculine arranged chambers, an almost entirely pitted shell surface (pseudopores) and a rounded aperture with a short simple tooth. Among the other species described as new are four hauerinids and two agglutinated foraminifera All new species described here occur sporadically in the shallow water back- and forereef environments of the lagoon (0–55m), and live infaunally and epifaunally in well-oxygenated, fine and coarse grained biogenic sediments. They are absent in muddy, organic-rich, low-oxygen sedimentary environments within bay inlets where variations of salinity are considerable.


MATERIAL AND METHODS
The present-day barrier, fringing and patch reefs of the lagoon at Madang, represent the largest reef system along the north coast of Papua New Guinea. The barrier reef parallels the N-S trending lagoon, is broken by three major passes, and extends over 17km from the Schering Peninsula in the S to the Ottilien Pass in the N (Fig. I). The lagoon is 1 to 4km wide and 10 to 52m deep. The central lagoon floor is covered by biogenic rubble, sand and calcareous silt. The reef crest is characterized by digitate, robust Acropora corals; the unconsolidated coral rubble floor has intervening sand channels and lacks extensive algal ridges. The four major inlet systems along the west coast of the lagoon (Madang, Nagada, Mililat Harbours and Bostrem Bay), are strongly influenced by the inflow of fresh water from rivers. The inlet bottoms are covered by a dark, organic-rich mud containing locally abundant scaphopods and a highly specialized foraminiferal fauna (Ammonia convexa, Spiroloculina attenuata, Parrellina hispidula and Elphidium sp. 1).
Fifty-seven samples covering major parts of the lagoon, the bay inlets and the forereef were collected in summer 1989 at depths ranging from 1 -52m (Fig. 1). The samples were collected by J.H. Lipps using SCUBA or a small rectangular pipe dredge. All sediment samples were washed over 63ym mesh sieves. Between 50 -450 specimens were picked out of each sample or sample split, identified to species level and counted. One hundred and eighty-two species were identified and photographed using SEM. The microhabitat distribution pattern of the foraminiferal faunal assemblages within the lagoon and a catalogue of the species identified will be published at a later date (Langer & Lipps, in prep.). In the following taxonomic note, a morphological description is given for the new genera and species. The taxonomy adopted here follows the classification of Loeblich & Tappan (1987 Description. Test free, heart-to fan-shaped in lateral view, broader than high in the adult stage, laterally compressed with subacute periphery. Initial chambers planispirally arranged and somewhat thickened (3-4 chambers), later chambers biserially arranged (15-17 chambers). Chambers rapidly increase in width as added. Sutures are curved and slightly depressed. Wall agglutinated by heterogenous material. The peripheral wall is penetrated by straight and branchingparapores (sensu Hottingeretal., 1990).Theaperture is a basal slit at the inner margin of the final chamber. Dimensions. Maximum test height of the holotype 0.57mm. Occurrence. Spiroplectinella hot tingeri is irregularly distributed in medium grained, backreef sediments (biogenic) in the lagoon of Madang, rare in the forereef area. Remarks. As has been shown by Bender (1989) and Cimerman & Langer (1991) the type species Spiroplectinella wrightiiis both initially planispiral and perforated by minute parapores. Spirorutilus became a junior synonym of Spiroplectinella (compare Hottinger et al., 1990a andBender, 1989). Therefore the species described here must be placed in Spiroplectinella Kisel'man. Description. Test free, subtriangular to wedge-shaped in lateral view, broader than high in the adult stage, laterally compres ed with subacute periphery. Initial part somewhat thickeneqC hambers are biserially arranged throughout and rapidly increase in width as added. In adult specimens the number of chambers is between 18 and 24. Sutures are slightly curved and somewhat depressed. Peripheral walls arecoarsely agglutinated by heterogenous material. Apertural face more smoothly finished.Theperipheralwallispenetrated by straight Explanation of Plate 1 Langer and branching parapores (sensu Hottinger et al., 1990). The aperture is a basal slit at the inner margin of the final chamber with a short flaplike lip bordered at its ends by apertural reentrants. Dimensions. Maximum test height of the holotype 0.56mm. Occurrence. Sahulia lu tzei is irregularly distributed in medium grained (biogenic) backreef samples in the lagoon of Madang, rare in the perireefal area. The species is lacking in muddy, organic rich sediments and in the low-salinity bay inlets where freshwater input is high. Remarks. Resembles the specimen figured by Said (1949, P1.1, fig. 7) asTextulariaconicad'Orbigny,butdiffersdistinctlyfrom the original drawings of Textularia conica by dOrbigny (1839, PI. 1, figs 19,201 and the neotype selected by Le Calvez (1977, p. 18, figs 1, 2) in its more V-shaped outline and coarse agglutinationand by the form of theapertural face. Interestingly the "short variety" of Textuluria conicu depicted by Brady (1884 P1. 113, figs la-b) and collected off Hong Kong seems to represent a juvenile specimen belonging to the species described here. It differs, however, in its rather fine agglutination, the height of its chambers and in possessing a distinct rim bordering the entire apertural opening. Description. Test free porcelaneous and imperforate, longer than broad, somewhat compressed with subacute periphery. Chambers distinct, arranged in a quinqueloculine pattern, polygonal in section; five chambers visible from the exterior. Sutures are depressed. Wall calcareous; shoulders and lateral parts of the test surface ornamented by numerous anastomosing costae which are parallel to oblique to the periphery of the chamber. Carinate edges of the chambers often becoming sinuous. Aperture produced on a short, slightly tapering neck, bordered by a circular rim and provided with two minute teeth with short bifid termination. Dimensions. Maximum test height of the holotype 0.71mm. Occurrence. Cycloforina collinsi is common in medium grained (biogenic) backreef samples in the lagoon of Madang. The species is lacking in muddy, organic rich sediments and in the low-salinity bay inlets where freshwater input is high. Remarks. Resembles strongly the specimens figured by Koutsoukos and Falcetta (1987, Pl., 1 figs 1-7) described under the name Adelosina pascuaensis from Easter Island in the southeastern Pacific. The species described herein differs from the latter in having a second, short bifid apertural tooth, more distinctive shoulders, is slightly more sinuate in apertural view and slimmer in side view.  Fig. 1, apertural view, (holotype) x90; Fig. 2, side view, (paratype) x40; Fig. 3, apertural view (note anastomosing microridges), (Holotype) x33.  Fig. 11, apertural view, (holotype) x120; Fig. 12, oblique side view, (paratype) x80; Fig. 13, side view, (holotype) x80; Fig. 14, enlargement of the pitted shell surface, (holotype) x800.

Langer
Spiroloculina. Wall calcareous, porcelaneous, imperforate. Surface with minute anastomosing microridges. Aperture ovate, produced on a short neck, bordered by a thickened rim and provided with a long, simple tooth with slightly thickened termination. Dimensions. Maximum test height of the holotype 1.25mm. Occurrence. Massilinoides baccaerti is rare in medium grained (biogenic) backreef samples in the lagoon of Madang. The species is lacking in muddy, organic rich sediments and in the low-salinity bay inlets where freshwater input is high. Description. Test small, porcelaneous, imperforate, subrectangular in lateral view, and star-like in apertural view. Chambers one-half coil in length, arranged in a quinqueloculine pattern so that finally five chambers are visible from the exterior. Chamber margins carinate; sutures slightly depressed. Surface covered with minute microridges. Aperture terminal, subcircular, bordered by a peristomal rim and provided with a broad, anvil-shaped, bifid tooth. Dimensions. Quinqueloculina stellicarinata is very rare in medium grained, (biogenic) backreef samples in the lagoon of Madang. The species is lacking in muddy, organic rich sediments and in the low-salinity bay inlets where freshwater input is high. Remarks. Differs from Cycloforina crassicarinata (Collins) in lacking the produced neck.
Family Hauerinidae Schwager, 1876 Subfamily Miliolinellinae Vella, 1957 Genus Pseudolachlanella gen. nov. Description. Test free, elongate multilocular; chambers one half coil in length, early stage cryptoquinqueloculine (sensu Bogdanovich, 19691, later with planes of coiling increasing to almost 180. to become nearly planispiral; chambers without a floor, broadly overlapping so that only three chambers are visible from the exterior; wall calcareous, imperforate, porcelaneous; surface smooth, aperture a very narrow, curved, elongate slit with parallel sides, provided with a long slender tooth with short, thickened termination. Type species. Pseudolachlanella slitella gen. nov., sp. nov. Remarks. The apertural features of this species do not correspond to those of any published genus. The new genus Pseudolachlanella differs from Lachlanella Vella, 1957 in its coiling mode, in its narrow and rather slitlikeapertural opening and in lacking the everted apertural rim. It differs also from Tviloculinella Riccio, 1950 in having a slitlike aperture with a long, slender, curved tooth, rather than an arch-like aperture covered by a broad apertural flap.
Remarks. The pitted surface and the apertural features place this genus in the subfamily Miliolinae Ehrenberg, despite the fact that this subfamily is defined by a terminal aperture with a trematophore. Interestingly Loeblich & Tappan (1987) included in the Miliolinae the genus Rupertianella with its terminal aperture bordered by arched lips.
Pitella differs from Triloculinella Riccio, 1950 in having a short, simple tooth and a pitted shell surface rather than an arch-like opening covered by a broad apertural flap. The new genus Pitella differs also from Rupertianella Loeblich & Tappan, 1985 in having a rounded aperture provided with a short tooth rather than a simple narrow and elongate slit bordered by slightly arched lips.
Porcelaneous foraminifera with a pitted test surface belonging to the family Miliolidae Ehrenberg are known since the Eocene. The function of the pseudopores is unknown and needs further investigation.  Hottinger et al., 1992). Sutures very slightly depressed. Aperture rounded, bordered by a weakly developed, nonpitted, apertural rim and provided with a short, simple tooth with thickened termination. Dimensions. Maximum test height of the holotype 0.64mm. Occurrence. Rare, irregularly distributed in the lagoon. Occurs in patchreef, forereef and lagoonal samples between 10 and 50m.

ECOLOGY
All species described above are rare in sediment samples from shallow water (0-55m) fore-and back-reef environments at Madang (0-55m). In the lagoon they are patchily distributed in fine and medium grained, biogenic sand and coarse, coral rubble. In thanatocoenoses their distribution matches the distribution of most of the larger symbiont bearing foraminifera (Assilina spp., Heterostegina depressa, Alueolinella quoyi, Sorites spp., Amphisorus hemprichii, Marginopora uertebralis). However, due to the lack of symbionts in the protoplasm of the new species, their depth and microhabitat requirements are less specific. Furthermore their morphology suggests also different microhabitat preferences (predominantly epifaunal and infaunal, compare Lipps, 1975, Langer, 1988, Kitazato, 1981. In the well oxygenated, unconsolidated, coarse coral rubble they probably live sheltered within the pore space. An epifaunal way of life, however, is more probable on fine biogenic sand. They are absent in all bay inlets where fresh water influence is high and the muddy sediments contain a high amount of organic material of terrestrial origin. Fig. 1