Collotheca orchidacea, Meksuwan, Phuripong, Pholpunthin, Pornsilp & Segers, Hendrik, 2013

Meksuwan, Phuripong, Pholpunthin, Pornsilp & Segers, Hendrik, 2013, The Collothecidae (Rotifera, Collothecacea) of Thailand, with the description of a new species and an illustrated key to the Southeast Asian fauna, ZooKeys 315, pp. 1-16 : 3-7

Collotheca orchidacea sp. n. Figs 2 C–F, 5E

Type locality.

Thale Noi Lake, Phatthalung Province, Thailand: 7°47.378'N, 100°8.969'E, on Utricularia sp., mostly on the surface of the bladder traps, 18 March 2012, P. Meksuwan leg.

Type specimens:

Holotype female mounted in permanent microscope slide, in Princess Maha Chakri Sirindhorn NaturalHistory Museum, Prince of Songkla University, Songkhla, Thailand, PSUZC-PK5PM2-1. Original label: " Rotifera , Family Collothecidae , Collotheca orchidacea Meksuwan & Segers, Locality: Thale Noi Lake, Phattalung Province, Thailand, Collected by P. Meksuwan 18-3-2012, Holotype"; two paratype females in permanent microscope slides, inRoyal Belgian Institute of Natural Sciences, Brussels, Belgium, IG 32158 RIR 204-205. Original label: " Rotifera , Family Collothecidae , Collotheca orchidacea Meksuwan & Segers, Locality: Thale Noi Lake, Phattalung Province, Thailand, Collected by P. Meksuwan 18-3-2012, Paratype".

Differential diagnosis.

The presence of a five-lobed corona separates the new species from most of the known members of genus Collotheca . In comparison with other Collotheca species having a five-lobed corona ( Collotheca algicola (Hudson), Collotheca ambigua (Hudson), Collotheca annulata (Hood), Collotheca bilfingeri Bērziņš, Collotheca ferox and Collotheca campanulata (Dobie)), Collotheca orchidacea sp. n. can be distinguished by its uniquely well-developed thumb-shaped lateral and semi-circular ventral corona lobes. It has a relatively broad infundibulum, and short foot and trunk, similar only to Collotheca ambigua and Collotheca ferox . In addition, Collotheca orchidacea sp. n. and Collotheca ferox hold their infundibulum and corona towards the substratum, whereas most other species including Collotheca ambigua and Collotheca campanulata normally hold their body and corona upright.

Description.

Habitus (Fig. 2 C–F): infundibulum funnel-shaped, trunk and corona opening held horizontally. Infundibulum and proventriculus about twice as long as the trunk. Infundibulum large, more than twice as wide as trunk. Foot short, length about half of trunk, contractile, with a short peduncle. Corona five-lobed: single dorsal, and a pair of well-developed lateral and of ventral lobes. Infundibulum with a weak line running parallel to the edge of the corona, and at least four ring-shaped structures (circular muscles?). Dorsal lobe large, elongate, basally with straight and converging lateral margins; parallel-sided medially, with smoothly curved antero-lateral corners. Tip of dorsal lobe transversally sinuate. Lateral lobes relatively the smallest, thumb-shaped, about half as wide as the dorsal lobe. Ventral lobes broadest, smoothly rounded, separated by a large and deep sinus. A group of setae present on the tip of all corona lobes.

Trophi (Fig. 5E) uncinate. Two pairs of subequal unci teeth relatively equal in length. All arrow head unci with middle groove.

Measurements.

Females total length ca. 340 µm. Length of infundibulum plus proventriculus ca. 190 µm, trunk ca. 100 µm, foot ca. 50 µm. Trunk width ca. 70 µm. Infundibulum width ca. 180; dorsal lobe length ca. 75 µm, width ca. 30 µm; ventral lobe width ca. 120 µm, ventral sinus depth ca. 30 µm.

Etymology.

The species name - orchidacea is a noun in apposition, and refers to the shape of the new species’ corona, which is reminiscent of the flower of certain orchid species. As such, the name of the species also refers to the biodiversity of Thailand, characterized by an abundance of orchid species.

Distribution.

The species is known from its type locality only.