Glyphidrilus champasakensis Chanabun & Panha

Chanabun, Ratmanee, Inkavilay, Khamla & Panha, Somsak, 2017, New species of semi-aquatic freshwater earthworm genus Glyphidrilus Horst, 1889 from Thailand and Laos (Oligochaeta, Almidae), ZooKeys 672, pp. 1-34 : 15-18

Glyphidrilus champasakensis Chanabun & Panha sp. n. Figs 1, 11, 12, Table 1

Type material.

Holotype: One adult (CUMZ 3426) in the banks of Mekong River at Ban Khonkhen, Champasak, Laos (15°02'21.2"N, 105°51'20.4"E), 106 meters elevation on 17 April 2014. Paratypes: 17 adults (CUMZ 3427), 2 adults (ZMH 14584), 2 adults (NHMUK), and 2 adults (RMBR), all specimens collected from type locality.

Diagnosis.

Glyphidrilus champasakensis sp. n. is a large sized earthworm with distinct expanded tissues of the clitellar wings on the sides of the body in XXIII, XXIV–½ XXXII, XXXII, XXXIII. Clitellum in XIX, XX– XLIX, L, LI, LII. Female pores, male pores and spermathecal pores not visible. Genital markings: medium paired or asymmetrical on aa in XII, XIII, XXXIII, XXXIV; paired or asymmetrical on bc in XVII, XVIII, XIX–XXII, XXIII, XXIV and XXXII, XXXIII, XXXIV, XXXV. Four pairs of seminal vesicles in IX–XII. Intestinal origin in XVI. Large ovaries in XIII–XIV. Spermathecae between 14/15-19/20.

Description of holotype.

Dimensions: body length 301 mm, diameter 5.0 mm in segment VIII, 5.0 mm before the clitellar wing in segment XXII, 5.0 mm after wing in segment XXXIII in clitellar region; body cylindrical in anterior part, quadrangular in transverse section behind clitellum. 424 segments. Body color pale brown with variations from red to pink at adjacent tissues of wing portion in different individuals of newly collected specimens. Clitellar wing on ventro-lateral part of clitellum in XXIII–XXXII, 10.0 mm in height, and 0.2 mm in width on both sides. Prostomium zygolobous. Dorsal pores absent. Clitellum annular in XIX– XLIX. Four pairs of setae per segment from II, setal formula aa:ab:bc:cd:dd = 2.0:1.0:2.0:1.0:3.0 in segment VIII and 2.0:1.0:2.0:1.0:2.5 in postclitellar segments. Female pores, male pores, and spermathecal pores not visible. Genital markings: medium paired or asymmetrical on aa in XIII, XXXIV, laterally paired or asymmetrical on bc in XIX–XXII and XXXIII, XXXIV.

Septa 4/5-8/9 thicker than between other segments others segment, 9/10-11/12 thick and 12/13 to the last segment thin. Gizzard small, globular in VIII. Intestine enlarged from XVI. Hearts, five pairs in VII–XI, first in VII and last in XI. A pair of holonephridia in each segment from segment XIV onwards. Seminal vesicles, four pairs in IX, X, XI, XII. Ovaries, two pairs in XIII and XIV. Testis free in X and XI. Prostate and accessory glands absent. Spermathecae sessile and diverticula absent, small elongated oval or globular between 14/15-19/20, about 0.1-0.3 mm in diameter, five to thirteen on each side per segment.

Variations.

Body lengths of adult (n = 24) ranged from 167-301 mm (212.75 ± 42.15), with 248-424 segments. Wings in XXIII, XXIV–½ XXXII, XXXII, XXXIII, clitellum in XIX, XX– XLIX, L, LI, LII. Genital markings: paired or asymmetrical on aa in XII, XIII, XXXIII, XXXIV; paired or asymmetrical on bc in XVII, XVIII, XIX–XXII, XXIII, XXIV and XXXII, XXXIII, XXXIV, XXXV.

Distribution.

The new species was found only on the banks of the Mekong River at Ban Khonkhen, Champasak, Laos.

Etymology.

The new species was named after Champasak, Laos, the type locality.

Remarks.

Here we compare Glyphidrilus champasakensis sp. n. to the species with spermathecae and a clitellum beginning from segment XIX. It differs from G. namdonensis sp. n. by G. namdonensis sp. n. having shorter wings in XXIV, XXV–XXVIII, XXX, and spermathecae between 14/15-18/19 (see Table 1).