Haementeria depressa

External morphology

Size reaching up to 122 in fixed specimen. Body lanceolate to oval; in preserved specimens, the outline is elliptical. The dorsal surface is convex and rugose, while the ventral surface is flat and smooth A complete, three-ringed somite appears to consist of six rings on the dorsal side and five rings on the ventral side. The transverse furrow subdividing the primary rings a1 and a3 continues uninterrupted from the dorsal to the ventral side; however, the furrow subdividing the neural ring a2 terminates on the dorsal surface before reaching the margins. On the dorsal surface, subdivision begins at Va3 (ring 14) and continues up to the penultimate ring, i.e., XXVI (a1 + a2). Dorsal sensillae appear as small horizontal or slightly oblique bars, numbering 3 pairs on each neural ring a2; they are situated upon a more or less prominent papilla—variously termed a sensilliferous papilla, segmental papilla, tubercle, or Lang's organ—which collectively form an equal number of longitudinal rows: two paramedian rows (located on the inner side of the latero-internal papillae), two lateral or intermediate rows, and two supramarginal rows. Tubercles or warts are arranged in four or five longitudinal rows: two latero-internal rows on the middle or neural rings a2 (or b3 + b4), and two latero-external rows on rings a3 (or b5 + b6); in certain specimens, a dorso-median row on rings a1 (or b1 + b2) may be added to this arrangement. These warts are situated within the furrow that divides each primary ring; furthermore, each secondary ring bears a transverse row of minute papillae. Also visible on the primary or neural rings a2 are a small tubercle on each side—positioned externally to the intermediate sensilla—and another marginal tubercle; supplementary tubercles also appear on the marginal fields of the posterior rings

Habitat & range

Habitat

Freshwater

Region

South America

Recorded from

Argentina, Chile, Uruguay, Brazil

Junior synonyms

Hamenteria gracilis