Gieysztoria queenslandica, Hochberg, Rick & Cannon, Lester R. G., 2001

Hochberg, Rick & Cannon, Lester R. G., 2001, A new species of Gieysztoria (Platyhelminthes; Rhabdocoela; Dalyelliidae) from a freshwater lake in Queensland, Australia, Zootaxa 11, pp. 1-8 : 3-6

Gieysztoria queenslandica n. sp.

Animals are up to 1.3 mm long and 560 µm wide, with a truncated head, wide trunk, and tapering caudal region ( Figure 1 ). Color of head region and lateral body margins pale orange; brown pigment spots are scattered randomly across trunk and tail. The head contains paired pigment cup ocelli located approximately 90 µm from the head tip. Posterior to the eyes is a pharynx doliiformis to 250 µm long. The oesophagus is short and leads to a globose intestine often containing lipid­like bodies and algal cells. Lateral to the intestine are the paired protonephridia, extending from the tip of the head to the tail, with at least one branch supplying the pharyngeal region. Small membrane­bounded packages (30­46 µm) of rhabdites are located at the posterolateral margins of the pharynx, at least one centered over the intestine, and two in the caudal region. Contained rhabdites are 3­4 µm long. Epidermis with polygonal cells containing up to 4 rhabdites, often in pairs; epidermal height to 8 µm with cilia 5­8 µm long.

The female reproductive system consists of a solitary ovary, Y­shaped oviduct, uterus, receptaculum seminis, bursa copulatrix, paired vitellaria, genital atrium and common gonopore ( Figure 2 ). The ovary, of variable size and often forming an S­shape, is located on the left side of the body. Medially, the ovary leads into a long oviduct that forms a Yshaped connection to both the genital atrium and receptaculum seminis; the posterior branch of the oviduct (ductus communis) connects to the genital atrium. The average diameter of the receptaculum seminis was 53 µm (4 specimens). Midway between the ovary and receptaculum seminis lies the bursa copulatrix, an elongate (60 µm) muscular bulb with thick muscular walls (8 µm) and a thinner but still muscular duct leading into the genital atrium. Paired vitellaria are finger­like in appearance and extend laterally along the bodywall to the edge of the pharynx. Posteriorly, the vitelline ducts join together to form a common vitelline duct before entering the genital atrium. Posterior to the genital pore is an elastic, sac­like uterus, often containing an egg from 96 µm to 170 µm long. The genital atrium opens to the exterior via the common gonopore that is surrounded by several finger­like glands.

The male reproductive system consists of paired testes, vasa deferentia, vesicula seminalis, vesicula granulorum, additional prostatic tissue, and a male copulatory organ (Figures 2­7). The paired testes are located in the posterior half of the body and often in variable positions. Several specimens had testes located along the lateral body wall and ventral to the vitellaria. Two specimens had testes located posterior to the intestine and close to the other reproductive organs. Each testis was relatively compact with vasa deferentia arising from the medial aspect. The vas deferens from the right testis was often coiled behind the vesicula seminalis. Both vasa deferentia lead to the anterior portion of the vesicula seminalis which is distinct from the posterior vesicula granulorum. The vesicula seminalis is a bilobed structure with thin walls and often filled with sperm. The vesicula granulorum is highly glandular and compact, sitting atop the male copulatory organ on the right side of the body. Additional prostatic tissue often surrounds the proximal region of the male copulatory organ.

The copulatory organ is oriented obliquely caudad and consists of two distinct regions: a belt­like girdle and numerous posteriorly­directed spines ( Figures 3­6 ). The girdle measures a maximum of 11 µm high (9­11µm, n= 10) by 88 µm wide (75­88 µm, n = 10). Dorsally, the girdle is semicircular, whilst ventrally the girdle folds inward at its center, giving the impression of a crescent shape. Arising distally from the girdle around its circumference are approximately twenty­seven to thirty­two spines (n = 10; Figure 4 ). There are up to twenty dorsal spines and six ventral spines on each side of the ventral infold; no spines arise from the infolded portion of the girdle ( Figure 4 ). The ventral spines on the left and right side are separated by the 3­4 µm infold. All spines are hollow with a narrow fingerlike base that is embedded in the girdle ca. 2 µm. From the base each spine widens to a maximum of 5 µm (3 µm hollow center with ca. 1 µm walls) and narrows distally forming a v­shaped tip. All spines are closely set and abut one another. Spine length is 45­48 µm long (n= 10), slightly concave and angled approximately 20° inward from the longitudinal axis, making the whole copulatory structure narrower by approximately 10% at its distal end. Spines around the lateral margin of the girdle appeared more concave than those on the dorsal and ventral aspect.

Type Repository: Queensland Museum, South Brisbane, Queensland, Australia.

Holotype: QM G218739, an adult specimen 1.3 mm long, de Faure’s wholemount of sclerotic male copulatory organ.

Type Locality: Shoreline of Clean Lake, University of Queensland, St. Lucia campus, Brisbane, QLD.

Etymology: The name refers to the state of collection

Figures

FIGURES 1 ­ 2. Gieysztoria queenslandica n. sp. 1, Features visible in live adult specimens; 2, Schematic of reproductive system. Scale bars = 150 m. BC, bursa copulatrix; DC, ductus communis; GA, genital atrium; GC, genital canal; GP, common gonopore; EG, egg; OV, ovary; RS, receptaculum seminis; T, testis; UT, uterus; V, vitellaria; VG, vesicula granulorum; VS, vesicula seminalis.

FIGURES 3 ­ 6. Male copulatory organ of Gieysztoria queenslandica n. sp. 3, Dorsal view of squashed male organ; 4, Ventral view of squashed male organ; 5, Schematic view of dorsal side of male organ. 6, Schematic view of ventral side of male organ.