Glyphidrilus sekongensis 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 : 12

Glyphidrilus sekongensis Chanabun & Panha sp. n. Figs 1, 9, Table 1

Type material.

Holotype: One adult (CUMZ 3422) in a stream at Ban Kiangkong, Lamarm, Sekong, Laos (15°33'30.6"N, 106°19'19.4"E), 472 meters elevation on 17 October 2013. Paratypes: 2 adults and 11 juveniles (CUMZ 3423) all same collection data as holotype.

Diagnosis.

Glyphidrilus sekongensis sp. n. is a small sized earthworm with the clitellar wings on the lateral side of the body in XXV–XXXI. Clitellum in XVI, XVII–XXXVI, XXXVII. Female pores, male pores and spermathecal pores not visible. Genital markings: paired or asymmetrical on bc in XVI, XVII–XXIV and XXXII. Four pairs of seminal vesicles in IX–XII. Intestinal origin in XVI. Ovaries in XIII–XIV. Spermathecae between 12/13-15/16.

Description of holotype.

Dimensions: body length 134 mm, diameter 2.4 mm in segment VIII, 2.3 mm before the clitellar wing in segment XXIV, 2.4 mm after wing in segment XXXII in clitellar region; body cylindrical in anterior part, quadrangular in transverse section behind clitellum. 329 segments. Body color pale brown with variations from red to pink on adjacent tissues of wing portions in different individuals of newly collected specimens. The posterior end on the dorsal surface is considerably broader than the ventral. Clitellar wing on ventro-lateral part of clitellum in XXV–XXXI, 4.0 mm in height, and 0.5 mm in width on both sides. Prostomium zygolobous. Dorsal pores absent. Clitellum annular in XVI–XXXVII. Four pairs of setae per segment from II, setal formula aa:ab:bc:cd:dd = 1.0:0.3:1.0:0.5:1.3 in segment VIII and 1.8:0.8:1.3:0.6:1.5 in postclitellar segments. Female pores, male pores, and spermathecal pores not visible. Genital markings: laterally paired or asymmetrical on bc in XVI–XXIV, XXXII.

Septa 5/6-8/9 thicker than between other segments, 9/10-14/15 thick and 15/16 to the last others segment, 9/10-14/15 thick and 15/16 to the last segment thin. Gizzard small, globular in VIII. Intestine enlarged from XVI. Hearts, four pairs in VIII–XI, first in VIII and last in XI. A pair of holonephridia in each segment from segment XIII 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 12/13-15/16, about 0.1-0.3 mm in diameter, two to seven on each side per segment.

Variations.

Body lengths of adult (n = 3) and juvenile paratypes (n = 11). Adults ranged from 90-134 mm (109.6 ± 12.2), with 237-337 segments. Juveniles ranged from 86+-130 mm (104.2 ± 14.0), with 209+-329 segments. Wings in XXV–XXXI, clitellum in XVI, XVII–XXXVI, XXXVII. Genital markings: laterally paired or asymmetrical on bc in XVI, XVII–XXIV, XXXII.

Distribution.

The new species was found in a stream at Ban Kiangkong, Lamarm, Sekong, Laos. Soils are slightly sandy mixed with black organic matter.

Etymology.

The species was named after Sekong, the type locality in Laos.

Remarks.

(see Table 1). Glyphidrilus sekongensis sp. n. differs from other species by the locations of external and internal characteristics such as wings, clitellum, the arrangement of genital markings, and spermathecae. The new species differs from G. vangviengensis Chanabun & Panha, 2011 from Song River, Vientiane, Laos by the latter having a shorter clitellum in XIX, XX–XXXV, XXXVI, XXXVII, widely paired genital markings in bc XVIII, XIX, XX, XXI–XXIV, XXXIII, XXXIV, paired on aa in XII, XIII, XIV, XV, and lacks spermathecae. Differences from G. yunnanensis Chen & Xu, 1977 reported from China are that G. yunnanensis has longer wings in XXII–XXXII, clitellum in XVIII–XXXVIII, and lacks spermathecae. Differences from G. mekongensis Panha & Chanabun, 2012 are that G. mekongensis has longer wings in XXIV–½ XXXIII, XXXIII, XXXIV, ½ XXXV, and lacks spermathecae. It differs from G. huailuangensis Chanabun & Panha, 2013 recorded from Najahlauy National Park, Ubon Ratchathani, northeast Thailand by the latter having a larger body size, clitellum in XII, XIII, XVI–XXXII, XXXIII, and lacks spermathecae. It differs from G. champasakensis sp. n. from Mekong River at Ban Khonkhen, Champasak, Laos by the latter having longer wings in XXIII, XXIV–½ XXXII, XXXII, XXXIII, longer clitellum in XIX, XX–XLIX, L, LI, LII, and spermathecae between 14/15-19/20.