Testudinella elongata, De, Willem H., 2009

De, Willem H., 2009, A review of the marine and brackish-water species of Testudinella (Rotifera: Monogononta, Testudinellidae), with the description of two new species, Zootaxa 2092, pp. 1-20 : 5-8

Testudinella elongata sp. nov.

( Figs 4 & 5 )

Testudinella sp. n. in De Smet (2005)

Diagnosis. Testudinella elongata sp. nov. is characterized by its strongly elongate and striate lorica; dorsal anterior margin with broad, flat median part and rounded lateral parts; ventral margin almost straight, rounded laterally; foot opening sub-terminal, inverted U-shaped; distal and penultimate foot pseudosegments long; manubria with well developed sub-ventral chamber; fulcrum with proximal opening.

Type locality. Mediterranean, Bay of Hyères, Île Porquerolles, France: near wreck of Prosper Schiaffino (Donateur), depth 50 m, distance from shore ~ 4 km, 31 December 2001.

Holotype. A female in a permanent, glycerine glass slide mount deposited in the Royal Belgian Institute of Natural Sciences ( RBINS), Brussels, Belgium, No. IG. 30986, RIR 192.

Paratypes. One female from type locality in RBINS (RIR 193); two females from Bègur, Bay of Aiguafreda, Furio de Aiguaxelida, Spain in ANSP 1974; 5 SEM trophi preparations in department of Biology, University of Antwerp.

Additional material. 20 females collected in psammon from Mediterranean: Spain, Bègur, Bay of Aiguafreda, Furio de Aiguaxelida (2), depth 28 m, distance from shore ~ 250 m, water temperature 24 °C, 17 August 2006; Italy, Elba Island: Punta Madonna (1), Scoglio della Nave Enfola (7), La Fonza Esterna (1), La Formiche di Ponente (4), Punta della Madonna di Ponente (2), Scoglietto di Portoferraio (3), depth 30–40 m, distance from shore ~ 50–1000 m, 25–30 September 2006.

Etymology. The species name elongata is a Latin adjective, and refers to the elongate lorica.

Description of female. The lorica ( Fig. 4 ) is strongly elongate, truncate anteriorly and rounded posteriorly. Ratio length/width 2.22–2.72 (average 2.41). The dorsal surface is ornamented with ~15–20 faint longitudinal ridges. The dorsal anterior margin shows a broad, flat median part connected by shallow folds to smaller rounded lateral lobes. The ventral margin is almost straight with a very broad and shallow median sinus, and rounded lateral edges. The dorsal anterior margin does not or only slightly projects beyond the ventral margin. Ventrally two longitudinal furrows delimit a protruding median part, which is ornamented with very faint longitudinal ridges as well. In cross-sectional view ( Fig. 4 C) both the dorsal and ventral margin appear arched. The sub-terminal foot opening is a wide inverted U-shaped slit on the ventral side. The foot ( Fig. 4 D) is composed of a long wrinkled proximal part, and a relatively long penultimate and somewhat longer distal pseudosegment ending in a ciliated cup. The ratio lorica length/position of antennae relative to dorsal anterior margin varies between 2.11–2.40 (average 2.22) for the dorsal antenna and 1.77–1.93 (average 1.83) for the lateral antennae. Two red eyespots.

Trophi malleoramate ( Fig. 5 ). The rami are relatively short elongate-triangular with rounded lateroventral margins. Alulae ( Fig. 5 B: a) very weakly developed, pointing caudally. Basal and sub-basal chambers forming a single chamber, opening latero-ventrally by a large common fenestra. Median apophyses shallow, asymmetrical and interlocking. The inner margins of the distal rami sections bear ~13–14/11–12 (left/right) strongly webbed arched rami scleropili. The basal apophyses are moderately developed ridges, composed of a series of fused scleropili. The fulcrum is short, plank-shaped, and more or less trapezoid in lateral view. It is composed of a double layer of long and appressed sclerite bodies, the caudal series of which is involved in the formation of the junction with the rami, and an anterior series which proximally border a distinct opening ( Fig. 5 A: fo). The unci plates consist of 9–10/9–10 (right/left) strongly webbed teeth. There are three straight major teeth with distinctly offset head in each uncus; the head of the midst teeth is only slightly smaller than the others. The minor teeth are weakly curved and lie close to each other; their head is elongate-lanceolate. The crescent shaped manubria are weakly sclerotized and composed of the superimposed dorsal, median, ventral and well developed sub-ventral chamber (indistinct in the SEM photographs due to crumpling up of weak manubria).

Male unknown.

Measurements. Lorica length 144–166 µm (mean=159 µm, N=12), lorica width 61–72 µm (mean=66 µm, N=12), penultimate foot pseudosegment 13–18 µm (mean=15 µm, N=9), distal foot pseudosegment 18–20 µm (mean=19, N=10); trophi: length × width 14.5–20.5 × 19.5–23.5 µm, ramus 10.5–14.0 µm, fulcrum 4.0–7.0 µm, largest major tooth 10.5–12.5 µm, manubrium 12.0–12.5 µm.

Comments. Testudinella elongata sp. nov. can not be confused with any congener. It is a close relative of T. obscura by its generally similar shape of the dorsal anterior lorica margin, foot opening and trophi shape, but is easily differentiated from the latter by its elongate lorica and the absence of a distinct V-shaped anteromedian notch of the ventral plate. Minute differences in trophi morphology concern the minor teeth which appear slightly curved in the new species and straight in the latter. With T. clypeata and T. bicorniculata sp. nov. it shares a similar foot opening and fulcrum with proximal opening.

Distribution and ecology. The species is known only from psammon collected in the Mediterranean, at depths of 28–50 m and distances from the shore varying from 50 m to ~ 4 km, during August, September and December. Water temperatures varied from 18–24 °C. It was always present in small numbers and occasionally co-occurred with the related T. obscura and T. bicorniculata sp. nov..

Figures

FIGURE 4. Testudinella elongata sp. nov. A. Lorica, dorsal view. B. Lorica, ventral view. C. Lorica, cross-sectional view. D. Foot pseudosegments. Scale bars A – C: 50 µm, D: 25 µm.

FIGURE 5. Testudinella elongata sp. nov., scanning electron microscope photographs of complete set of trophi. A. Frontal view. B. Caudal view. Scale bar 10 µm. a: alula, fo: fulcrum opening.