Amynthas tontong Panha & Bantaowong

Bantaowong, Ueangfa, Chanabun, Ratmanee, Tongkerd, Piyoros, Sutcharit, Chirasak, James, Samuel W. & Panha, Somsak, 2011, New earthworm species of the genus Amynthas Kinberg, 1867 from Thailand (Clitellata, Oligochaeta, Megascolecidae), ZooKeys 90, pp. 35-62 : 40-41

Amynthas tontong Panha & Bantaowong sp. n. Figs 13

Description of Holotype:

Dimensions; 53 mm by 2.7 mm at segment X, 2.6 at segment XX, 2.2 mm at clitellum; body cylindrical with 80 segments. Setae regularly distributed around segmental equators, numbering 42 at VII, 52 at XX, no visible setae between mp, setae formula AA:AB:ZZ:ZY= 1.5:1:1:1 at XIII. Single fp at XIV. Prostomium epilobic. First dorsal pore at 5/6. Clitellum annular XIV–XVI with no setae.

A pair of indistinct rounded mp in XVIII, 0.19 mm circumference apart ventrally; distance between mp 1.0 mm at 5th seta line. Genital markings closely paired located medial to male pore level in intersegment 18/19. Sp paired in 7/8 at 4th seta line, each small, lip-like structure within porophore, 0.10 circumference apart ventrally; distance between sp 1.0 mm. Genital markings near sp absent.

Septa 5/6 and 6/7 thick, 7/8 thin, 8/9 and 9/10 absent 10/11-13/14 thin. Gizzard large within VIII–X, intestinal origin in XV, no lymph glands observed. Typhlosole small from XXVII. Ic originated from XXVII extending forward to XXV, simple finger-shape. Hearts esophageal in X–XIII. Holandric; testes and funnels in ventrally joined sacs in X–XI. Sv paired in XI–XII. Prostates in XVIII; prostatic ducts long slender with U-shape. Genital marking glands absent.

Ovaries in XIII. Sc one pair in VIII; ampulla thumb shape, duct stout, shorter than ampulla. Diverticulum slender stalk with spherical knob terminal, no genital marking glands observed.

All the key morphological characters of the holotype and paratype specimens are given in Table 3.

Variation:

The holotype measures 53 mm body length with 80 segments; the three paratypes range in size from 39-41 mm (40.33 ± 1.15 mm) body length with 71-74 segments (Table 3).

Type locality:

Tontong Waterfall, Nan province, Thailand, 19°12'35.9"N, 101°04'13.7"E, 1,128 meters elevation (10th October 2009).

Etymology:

This species was named after the type locality, Tontong Waterfall.

Type material:

The holotype (CUMZ 3206) and two paratypes (CUMZ 3207) are deposited in Chulalongkorn University, Museum of Zoology. Another paratype will be deposited in the Biozentrum Grindel und Zoologisches Museum, Hamburg, Germany (UHH).

Habitat:

Found in the top soil at about 10 cm depth, the soil surface covered with leaf litter of deciduous forest which originated at the Tontong Waterfall area. The soil was carefully dug close to surface casts. Most surrounding areas have been modified to agricultural fields.

Diagnosis:

Amynthas tontong sp. n. is a small sized terrestrial earthworm with a close indistinct pair of male pores with a pair of genital markings in intersegment 18/19. Spermathecae consists of a thumb shaped ampulla and a spherical terminal knob shaped diverticulum. Genital marking glands absent, first dorsal pore in 5/6, intestinal caeca simple, intestinal origin XV, septa 8/9/10 absent, testis sacs joined ventrally.

Remarks:

Amynthas tontong sp. n., along with Amynthas srinan sp. n. and Amynthas exiguus exiguus , is one of the smallest sized Amynthas ever recorded in Thailand. The basic external characters are easily seen in both newly collected and preserved materials. Compared with the two other closely related species from Laos, Amynthas chandyi Hong, 2008 and Amynthas namphouinensis Hong, 2008, which belong in the same zebrus-group, Amynthas chandyi is similar to Amynthas tontong sp. n. However, it differs in the specific details of the significant characters, such as the distance between the mp in Amynthas tontong sp. n. is 1.0 mm for the holotype and ranged from 1.0-1.2 mm (0.93 ± 0.12 mm), while in Amynthas chandyi it ranged from 1.5-2.4 mm. The distance between the male pores as a fraction of the estimated circumference of the 18th segment is 0.15-0.19 in Amynthas tontong sp. n., but 0.14-0.32 in Amynthas chandyi . The arrangement of the genital markings of both species are totally different, and the distance between a pair of sp is also different, being 0.8-1.0 mm (1.1 ± 0.1 mm) in Amynthas tontong sp. n. and 1.2-1.5 mm for Amynthas chandyi . Moreover, Amynthas tontong sp. n. has no genital markings near to the sp,whilst Amynthas chandyi exhibits circular genital markings in various locations, paired or single mid ventral in VII, VIII; usually 3 or 4 in total.

Alcohol-preserved paratype specimens of Amynthas tontong sp. n. belonged to a single DNA barcode cluster, with an intra-cluster divergence of 0.005 (N=3), and diverging from Amynthas phatubensis sp. n. by 0.294, and by 0.189 for an undescribed species. An undescribed morph at Tham Pha Tub diverged by 0.100, and may represent a subspecies. A consensus sequence is in Appendix 1.