Australobranchipus, Rogers, Christopher, Timms, Brian V, Jocquè, Merlijn & Brendonck, Luc, 2007

Rogers, Christopher, Timms, Brian V, Jocquè, Merlijn & Brendonck, Luc, 2007, A new genus and species of branchipodid fairy shrimp (Crustacea: Branchiopoda: Anostraca) from Australia, Zootaxa 1551, pp. 49-59 : 50-57

Branchipodidae Baird, 1852 sensu Daday, 1910 and Weekers, 2001 Australobranchipus gen. nov.

Etymology. The genus name underlines the Australian occurrence of this branchipodid genus. The name Branchipus refers to the type genus of the family. Gender is male.

Type species. Australobranchipus parooensis sp. nov.

Synonymy. Undescribed branchipodid genus and species. Timms, et al. 2004; New Genus A. Timms, 2004

Diagnosis. Rigid portion of gonopods inflated, slightly expanded over genital segments. Everted gonopods extending to third or fourth abdominal segment. Rigid basal portion of each gonopod subcylindrical, smooth, bearing a single medial rounded projection. Distal eversible portion of each gonopod subcylindrical with an anteriolateral longitudinal row and a posteriolateral longitudinal row of flattened, posteriorly directed spines, which unite at the apex of the gonopod at the gonopore. Gonopod with an anteriomedial and a posteriomedial longitudinal row of flattened, posteriorly directed spines on the distal quarter. Frontal appendages present. Female with brood pouch sub-cylindrical not extending beyond second abdominal segment. Amplexial groove present, more pronounced laterally. Female with rudimentary dorsal ornamentation. Cercopods margined with spines. Two species from eastern Australia.

Differential diagnosis. The family Branchipodidae contains six genera: Australobranchipus gen. nov., Branchipus Schaeffer, 1766 , Branchipodopsis Sars, 1989 , Rhinobranchipus Brendonck, 1995 , Metabranchipus Masi, 1925 , and Pumilibranchipus Hamer & Brendonck, 1995 . Australobranchipus lacks the ornamentation of the rigid proximal portions of the gonopods that characterize Metabranchipus and Rhinobranchipus . The basal portions of the gonopods in Metabranchipus bear lateral protrusions that are covered with fine spines and the ventromedial processes have a serrated medial margin ( Brendonck 1995a, Brendonck & Belk 1997). Conversely, in Rhinobranchipus , in addition to the ventromedial process, a lobiform ventral projection tipped with a small spine is also present. Otherwise the gonopod rigid basal portions of Australobranchipus are similar to Branchipus , Branchipodopsis , and Pumilibranchipus . In Branchipus the medial process tends to be elongated, curved, and apically acute, whereas in Branchipodopsis the medial process may be a small rounded protuberance, or an acute projection ( Brendonck 1995a, Brendonck and Belk 1997). Pumilibranchipus has an acute medial projection, and just posterior to the first projection is a small spiniform projection ( Hamer 1994, 1999, Brendonck 1995b, Brendonck & Belk 1997). In Australobranchipus the medial projection is short and hemispherical, similar to some Branchipodopsis .

The distal eversible portion of the gonopods in Australobranchipus bears four distinct, separated longitudinal rows of small denticuliform spines, whereas Rhinobranchipus , Branchipus , Branchipodopsis , and Metabranchipus have different arrangements of large papilliform spines.

The form of Australobranchipus gonopods is most similar to Pumilibranchipus . The eversible portion of the gonopod in Pumilibranchipus is subequal in length to the rigid basal portion, and bears a single, longitudinal row of 4 to 5 posteriorly directed subconical spines, each with a serrate apex ( Hamer 1994, 1999, Brendonck 1995b, Brendonck & Belk 1997). In contrast, Australobranchipus has the distal eversible portion twice as long as the basal portion, and four longitudinal rows of ten or more small, flattened, smooth spines.

Australobranchipus parooensis sp. nov. ( Figures 1 , 2 )

Synonymy. Undescribed branchipodid genus and species. Timms, Shepard & Hill, 2004; New Genus A. Timms, 2004.

Type material. Holotype, NEW SOUTH WALES: Bloodwood Station, 130 km nw of Bourke, Marsilea Pond (29° 33’ S, 144° 52’ E), male 5 August 1998, B.V. Timms, AM P67196; Allotype, same collecting data as holotype, female (ovigerous), AM P67197. Paratypes, same collecting data as holotype, one male and four females, P67198. All specimens very small, <10mm long.

Other material. Same locality as holotype, eight males and eight females, 7 October 1999, B.V. Timms, AM P67199. NEW SOUTH WALES, Muella Station, 125 km NW of Bourke, pond near homestead, (29° 31’ S, 144° 56’ E), 20 specimens, 7 October 1999, B.V. Timms, AM P67200. QUEENSLAND: Currawinya National Park, via Hungerford, ‘KA’ claypan (28° 51’ S, 144° 27’ E), one male, 9 December 1996, B.V. Timms, QM W27982. SOUTH AUSTRALIA: Katarapko Island, Murray River near Loxton, (34o 22’ S, 140o 35’E) 19 October 1984, C. Madden.

Description. Male. Head rounded. First antennae as long as clypeus, apex directed laterally, and bearing a few small aesthetascs. Eyes large, about half as wide as head. Frontal appendages present, fused proximally, and separating into two distinct branches extending beyond distomedial clypeal margin. Each frontal appendage branch spinose apically, and bearing two lateral spinose rami. Frontal appendage spines subconical. Clypeus rhomboidal. Distal part of clypeus chitinized and simple. Clypeus with pair of anteroposteriorly flattened ventral projections fused medially. Second antennal distal antennomere arcuate, curving medially and posteriorly, with distal most portion bent 90 degrees laterally, and apex slightly hooked posteriolaterally.

Praeepipodites evenly rounded. Epipodites oblong and rounded. Exopodites arcuate, apically rounded, and margined with long setae. Endopodites bilobed, each lobe broadly rounded; medial lobe slightly smaller than lateral lobe. Endopodite lateral lobe margined with long fine setae as long as the endopodite or longer; medial lobe margined with stout, straight spines. Endites with long setae.

Thorax and abdomen smooth except for segmentation. Gonopods as for the genus. Cercopods broad and triangular, lateral and medial margins with long spines, each bearing a setose fringe.

Female. Head rounded. Eyes large, more than half the width of the head. First antennae as long as second antennae. Second antennae lamelliform, abruptly narrowing to an acute apex. Labrum truncate, with medial process explanate. Thoracopods as in male, except endopodite reduced, especially the medial lobe with its spines greatly reduced.

Amplexial groove present laterally as a deep fold between thoracic segments XI and XII. Thoracic segment X with a ventrolateral protrusion, slightly chitinized, and directed posteriorly. Thoracic segment IX with a smaller ventrolateral protrusion. Brood pouch broadly ovate, fused entirely to thorax, gonopore projecting over base of abdominal segment I. Abdomen and cercopods as in male.

Egg. Resting eggs have an irregular spherical shape with polygonal sculpturing characterized by sharp upstanding ridges (Figures10, 11, 12 & 13 in Timms et al. 2004). Diameter: 250 μm.

Etymology. The species name refers to the Paroo region in eastern Australia where most collections of this new taxon came from.

Type locality. Marsilea pool on Bloodwood Station 130 km northwest of Bourke, NSW (29° 33’ S, 144° 52’ E), an oval shaped depression 33m by 25m and normally filling to 20–35 cm deep. This pool may fill twice a year in wet years (La Niña years) but then be dry for many years (during El Niño events); from 1987- 2004 it filled six times, but had some water about twice as frequently. When filled, water usually persists for only two to six weeks. Pool waters are generally clear, though on windy days may become turbid due to suspended clays (Secchi depth 15 cm). Water is always fresh and of very low conductivity (<100 uS/cm).

The pond is dominated by Nardoo, Marsilea drummondii A. Braun, 1853 . Other branchiopods present were Branchinella arborea Geddes, 1981 (matures two to three weeks after filling) and B. australiensis (Richters, 1876) (matures three to five weeks after filling). With A. parooensis maturing four to eight days after filling (see below), these three species usually form a succession of dominant species. Other large branchiopods present included Eulimnadia sp., Caenestheriella packardi (Brady, 1886) and Triops sp. There was also an abundance of coleopterans, culicids, chironomids and various notonectids and corixids. Odonates, ephemeropterans, plecopterans and molluscs have never been found in this pond. Branchinella wellardi Milner, 1929 has previously been reported from this pond ( Timms & Sanders, 2002)

Australobranchipus gilgaiphila sp. nov. ( Figures 3 , 4 )

Type material. Holotype, QUEENSLAND: Eringibba National Park SSE of Glenmrogan, gilgai pool along western boundary, 2 km N of SW corner of park (27° 17.85’ S, 149° 41.316’ E) male, 1 December 2001, Craig Eddie, QM W28232, Allotype, same collecting data as holotype QM W28233 female (ovigerous). Paratypes, same collecting data as holotype QM W28234 two males and two females. All specimens very small, <10mm long.

Other material. QUEENSLAND: 25 km west of Bollon, pool besides Balonne Highway (28° 01’ S, 147° 03’ E), 26 June 2005, B.V. Timms, QM W27983. QUEENSLAND: Southwood National Park, 30 km WSW of Moonie, gilgai pool (27° 48.372’ S, 150° 05.028’ E), three males, 9 females, 8 December 2005, R. Johnson, QM W W28235.

Description. Male. Head rounded. First antennae as long as clypeus, apex directed laterally, and bearing a few small aesthetascs. Eyes large, about half as wide as head. Frontal appendages present, fused proximally, and separating into two distinct branches extending beyond distomedial clypeal margin. Each frontal appendage branch spinose apically, and bearing one lateral spinose ramus. Frontal appendage spines digitiform, becoming subconical apically. Distal part of clypeus chitinized and simple. Clypeus with pair of anteroposteriorly flattened ventral projections broadly separated and each bearing a lateral ridge on the anterior surface. Second antennal distal antennomere arcuate, curving posteriorly in the basal fourth and medially in the medial third. Distal antennomere distal fifth anterolaterally and posteromedially expanded with rounded margins, tapering to apex, which is slightly curved laterally.

Praeepipodites evenly rounded. Epipodites oblong and rounded. Exopodites oval, and margined with long setae. Endopodites arcuate, margined with long setae, and a few small spines apically. Endites with long setae.

Thorax and abdomen smooth except for segmentation. Cercopods broad and triangular, lateral and medial margins with long spines, each bearing a setose fringe.

Female. Head rounded. Eyes large, more than half the width of the head. First antennae 1.5 times as long as second antennae. Second antennae lamelliform, abruptly narrowing to an acute apex. Labrum truncate, with medial process explanate. Thoracopods as in male.

Amplexial groove present laterally and dorsolaterally as a deep fold between thoracic segments XI and XII. Thoracic segment 11 slightly chitinized dorsally with rows of small spinules. Thoracic segment X with a ventrolateral rounded lobe, slightly chitinized, with rows of small spinules, and directed posteriorly. Thoracic segment IX with a smaller ventrolateral protrusion. Brood pouch broadly ovate, fused entirely to thorax, gonopore projecting over base of abdominal segment I. Abdomen and cercopods as in male.

Egg. Resting eggs have an irregular spherical shape with polygonal sculpturing characterized by sharp upstanding ridges. Diameter: 250 μm.

Etymology. The species name refers to the typical wetland habitat (gilgai, a native Australian word) and lover of (philios, from Greek) where this species is found in eastern Australia.

Type locality. The type locality is a gilgai pool about 20 m in diameter and <50 cm deep in Brigalow ( Acacia harpophylla F. Müller ex Bentham, 1864 ) woodland. It contains clear water of low conductivity. No other large branchiopods were present at the time of collection. The roadside pool near Bollon had Branchinella arborea and juvenile B. australiensis present as well as the new fairy shrimp.

Little is known of the ecology of Australobranchious gilgaiphila . In the Bollon pool adults were collected within two weeks of rain, so its life cycle is probably short also. So far it has been found only in clear water pools, thus joining a small number of Branchinella species ( Timms & Sanders, 2002) that prefer clear waters compared to the ubiquitous turbid waters of the inland.

Figures

FIGURE 1. Australobranchipus parooensis n. sp.: male, head, left side, anterior view.

FIGURE 2. Australobranchipus parooensis n. sp., A-F male, G egg: A) head, anterioventral view; B) head and anterior portion of thorax left lateral view; C) right second antenna, detail of apex, dorsal view; D) cercopods, ventral view; E) detail of coiled frontal appendage rami, right lateral view; F) gonopods, retracted, left lateral view; G) egg.

FIGURE 3. Australobranchipus gilgaiphila n. sp.: A) female, head, left side, anterior view; B) male, head, left side, anterior view; C) female brood pouch; D) male right cercopods, ventral view; E) male gonopods (left gonopod everted), ventral view.

FIGURE 4. Australobranchipus gilgaiphila n. sp., A-G male, H egg: A) head, posterioventral view; B) head, anterioventral view; C) head and anterior portion of thorax right lateral view; D) right second antenna, detail of apex, anterior view; E) right second antenna, detail of apex, dorsal view; F) detail of coiled frontal appendage branches, anterior view; G) detail of coiled frontal appendage rami, right lateral view; H) egg.