Amynthas castaneus ( Michaelsen, 1899 )

Amaliah, Rizki, Fahri, F. & Nguyen, Anh D., 2024, New species and new record of the genus Amynthas Kinberg, 1867 (Oligochaeta: Megascolecidae) from Sulawesi, Indonesia, Raffles Bulletin of Zoology 72, pp. 116-126 : 122-123

Amynthas castaneus ( Michaelsen, 1899)

( Table 1, Fig. 3 )

Amyntas [ sic] castaneus Michaelsen, 1899: 56–58 (type locality: Matinang-Kette, North Celebes).

Material examined. 2 clitellates ( UNTAD. Oli 0013), primary forests, near Lake Kalimpa’a , Lore Lindu National Park (01°19′35.27″S, 120°18′36.71″E), elevation of 1,674 m asl, South Kulawi, Central Sulawesi province, Indonesia, leg. Rizki Amaliah et al., 3 November 2016 .

Description. Small-sized worm, length 56–64 mm (n=2), diameter 1.5–2.0 mm, and segments 72–83. Prostomium epilobous. First dorsal pore in 12/13. Setal numbers: 28–31 in v, 32–38 in vii, 29–36 in viii, 34–38 in xxv, and 10–12 between male porophores in ventral xviii. Three pairs of spermathecal pores in lateroventral 6/7/8/9, distance between spermathecal pores about 0.35x body circumference ventrally ( Fig. 3A ). Male pores simple, distance between male pores about 0.2x body circumference ventrally. Genital markings present, small, widely paired in pre- and post-setal xvii, and pre-setal xviii–xix ( Fig. 3D ). Septa 8/9/10 absent. Spermathecae large, paired in vii–ix ( Fig. 3B ). Spermathecal ampulla rounded, duct enlarged, about 2/5 as long as ampulla. Diverticulum cylindrical, about 1/2 as long as ampulla, attached to ducts. Holandric. Prostatic duct C-shaped. Accessory gland present, stalked. Oesophageal gizzard large in viii–x. Oesophageal hearts paired in xi–xiii. Intestine beginning in xv; caeca originating from xxvii extending anteriorly to xxv ( Fig. 3E ), paired laterally. Typhlosole simple. Testes sacs yellowish, small, ventrally paired but separated in x–xi. Seminal vesicles in xi–xii. Ovaries paired in xiii; ovisacs paired in xiii. Prostate glands racemose, paired ( Fig. 3C ).

Habitat and ecology. Specimens were collected in primary forest near Lake Kalimpa’a, Lore Lindu National Park, South Kulawi, Central Sulawesi at the elevation of 1,674 m asl. This species was found at the depth of 15–20 cm in moist and sandy soils around rocks and decayed wood.

Remarks. This is the second record since it was first described by Michaelsen (1899) from Matinang-Kette, North Sulawesi. Specimens described by Michaelsen are slightly different from the present material in having diverticulum with slender stalk and an elongated rod-shaped seminal chamber.

Figures

Fig. 3. Amynthas castaneus from Lore Lindu National Park, Central Sulawesi (UNTAD. Oli 0014). A, spermathecal pores (sp) B, spermathecae, right side in vii–ix (amp = ampulla; dv = diverticulum) C, prostate gland D, male pore region (mp = male pore, gm = genital markings) E, intestinal caecum. Scale bars = 1 mm.