Glyphidrilus kralanhensis Jirapatrasilp, Chanabun & Panha

Jirapatrasilp, Parin, Prasankok, Pongpun, Sutcharit, Chirasak, Chanabun, Ratmanee & Panha, Somsak, 2016, Two new Cambodian semi-aquatic earthworms in the genus Glyphidrilus Horst, 1889 (Oligochaeta, Almidae), based on morphological and molecular data, Zootaxa 4189 (3), pp. 543-558 : 549-551

2. Glyphidrilus kralanhensis Jirapatrasilp, Chanabun & Panha , sp. n.

( Figure 3 )

Type specimens. Holotype CUMZ 3400 (adult; Fig. 3 ), paratypes CUMZ 3401 (three adults and six juveniles), and ZMH 14586 (one adult), leg. P. Jirapatrasilp, C. Sutcharit, W. Siriwut and R. Srisonchai, 6 Feb 2015.

Type locality. Tapan River , Kralanh District, Siem Riep Province, Cambodia, 13º35’24.5”N, 103º24’27.8” E, 8 m amsl. ( Fig. 1 Loc. 14, Fig. 4 C).

Diagnosis. Wings between segment 23, 24, ½25, 25–26, 27, ½28, 29, 30, 31; clitellum in 19, 20–35, 37; genital markings paired or asymmetrical on bc in pre-wing 20, 22–24, and post-wing 26–29, 30; intestine enlarged in 16; ovaries in 13–15; spermathecae sessile, elongated oval or globular between 13/14–21/22 ( Table 2 ).

Description of holotype. Body length 107 mm, diameter 3.63 mm in segment 8, 4.06 mm in front of wings in segment 22, 2.71 mm behind wings in segment 43; body cylindrical in anterior part, quadrangular in cross-section behind clitellum. 314 segments. Body color pale brown with reddish tint from the first segment to clitellar portion. At posterior end dorsal surface broader than ventral. Clitellar wings on ventro-lateral part of clitellum, left wing in 25–30, right wing in 24–29, both 3.90 mm in height and 0.71 mm wide. Prostomium zygolobous. Dorsal pores absent. Clitellum annular but not totally fused in 20–37. Four pairs of setae per segment from 2, setal formula aa: ab: bc: cd: dd = 1.27: 0.59: 1.25: 0.74: 1.26 in segment 8 and 1.25: 0.46: 1.05: 0.52: 1.65 in postclitellar segments. Female, male and spermathecal pores not visible. Genital markings paired on bc in 23.

Septa 5/6–7/8 thickest, 8/9–11/12 thick and 12/13 to the last segment thin. Gizzard globular within 8. Intestine enlarged from 16. Dorsal blood vessel anterior to 7. Hearts in 7–11. A pair of nephridia in each segment, rudimentary in 13, small in 14, and normal in 15 onwards. Seminal vesicles in 9–12. Ovaries in 13–15. Testis in 10–11. Prostate and accessory glands absent. Spermathecae sessile, elongated oval or globular in 13/14–21/22, about 0.2 mm in diameter, one to eleven on each side per segment.

Variation. Body lengths of adult paratypes (4) ranged from 85–116 mm (mean ± S.D. = 100.5 ± 13.7), with 205–314 segments. Wings begin in 23, 24, ½25, or 25 and end in 26, 27, ½28, 29, 30, or 31; the most frequent position is 24–30, 31. Clitellum begins in 19 or 20 and ends in 35 or 37. All specimens have genital markings paired or asymmetrical on bc in pre-wing 23, some in 20–22, 24, and post-wing 26–29, 30. The most frequent position of spermathecae is 13/14–20/21; some occur in 21/22 ( Table 2 ).

Distribution. The new species is known only from the type locality.

Habitat. The species was found on river banks where the worm casts covered the surface. The earthworms occurred in the loamy sand topsoil at about 10 cm depth.

Etymology. The species was named after Kralanh district, the type locality.

Remarks. Glyphidrilus kralanhensis sp. n. is the only species in the genus to contain three pairs of ovaries in 13–15 (hypergyny), and also has spermathecae in more posterior segments compared to the other taxa. For further comparison of Mekong Glyphidrilus species, see Table 2 .

Figures

FIGURE 1. Map of sampling localities of Glyphidrilus spp. in the Mekong River Basin in Thailand, Laos and Cambodia. Locality numbers (1 – 14) correspond to those in Table 1 and 2. Numbers with an asterisk designate type localities. Loc. 1: Rice field at Ban Thatoom, Mueang, Mahasarakham, Thailand. Loc. 2: Huailuang waterfall, Najahlauy, Ubon Ratchathani, Thailand. Loc. 3: Mekong River, Khong Chiam, Ubon Ratchathani, Thailand. Loc. 4: Khut Khu Islets, Chiang Khan, Loei, Thailand. Loc. 5: Bueng Kan Mekong River pathway, Mueang, Bueng Kan, Thailand. Loc. 6: Salung Beach, Pho Sai, Ubon Ratchathani, Thailand. Loc. 7: Kang Saphue, Mun River, Phibunmangsahan, Ubon Ratchathani, Thailand. Loc. 8: Song River, Vangvieng, Vientiane, Laos. Loc. 9: Phonevichith Guesthouse, Houayxay, Bokeo, Laos. Loc. 10: Ban Arjsamart, Muang, Nakon Panom, Thailand. Loc. 11: Pakse Mekong River pathway, Pakse, Champasak, Laos. Loc. 12: Stream near Praduk Temple, Banteay Srei, Siem Riep, Cambodia. Loc. 13: Banteay Srei Temple, Banteay Srei, Siem Riep, Cambodia. Loc. 14: Tapan River, Kralanh, Siem Riep, Cambodia.

FIGURE 3. Morphology of the holotype (CUMZ 3400) of G. kralanhensis sp. n. A. External ventral view. B. Internal dorsal view after dissection; some anterior pairs of nephridia are not shown.

FIGURE 4. A. Type locality of G. jamiesoni sp. n. on the stream banks near Praduk Temple, Banteay Srei, Siem Riep. B. Same as A, casts. C. Type locality of G. kralanhensis sp. n. on the bank of Tapan River, Kralanh, Siem Riep. D. Paratype specimen of G. jamiesoni sp. n. (CUMZ 3398). E. Paratype specimen of G. kralanhensis sp. n. (CUMZ 3401). Both specimens photographed immediately after the first preservation in 30 % (v / v) ethanol.