Amynthas carnosus carnosus Goto & Hatai, 1899

Han, Anne Charis N., Zhang, Yufeng, Miao, Pu, Wu, Shaolong, Xiao, Nengwen, Qin, Mingyan, Zhao, Huifeng, Wu, Donghui & Aspe, Nonillon M., 2024, Distribution and systematics of the cosmopolitan Amynthas carnosus complex (Crassiclitellata, Megascolecidae) from eastern Asia, Zoosystematics and Evolution 100 (3), pp. 1061-1073 : 1061-1073

Amynthas carnosus carnosus Goto & Hatai, 1899

Perichaeta carnosa Goto & Haitai, 1899: 15 .

Pheretima carnosa – Kobayashi 1936: 115.

Amynthas carnosus – Sims and Easton 1972: 235. Blakemore 2012: 36 ; 2013 a: 58; 2013 c: 101. Carrera-Martínez and Snyder 2016: 297 . Chang et al. 2016: 505.

Amynthas pingi ( Stephenson, 1925) – Sims and Easton 1972: 235. Blakemore 2013 c: 112.

Material examined.

Specimen IDs: 362 R 1 _ 01, 02, 04, 05, 06, 07, 09, seven matures from Nanshan Park, Jinzhou, Liaoning; 533 R 70 _ 08, 09, 10, three matures from Jinjiang Mt. Park, Dandong, Liaoning; LFXHR 7 _ 02, 04, 05, three matures from Zhuti Park, Xianghe County, Langfang, Hebei; LFSF _ 013, one mature from Langfang Normal University, Anci District Langfang, Hebei; E 29 _ 05, one mature from an anonymous park in Dongli District, Tianjin Municipality; HNLNR 2 _ 04, 05, 06, three matures from the tobacco field in Xiaojie Town, Luoning County, Luoyang, Henan; HNSQ _ 07, 13, 15, three matures under the bushes in Shangqiu Normal University, Liangyuan District, Shangqiu, Henan.

Diagnosis.

Length 105–210 mm. Spermathecal pores having four pairs in 5 / 6 / 7 / 8 / 9, rarely 3 pairs in 6 / 7 / 8 / 9, with pre-intersegmental hemispherical arc (spermathecal papillae). Dorsal pores typically from 12 / 13. Pre-clitellar genital markings typically with two pairs, pre-setal in VIII and IX; these genital markings paired either widely or closely apart (B 1 and B 2, Fig. 3 ); Post-clitellar genital markings prominent, up to three pairs median to male pores; first pair pre-setal on XVIII, slightly median to male pores; second pair post-setal and more medial than the first; third pair pre-setal in XIX (Fig. 4 ). Male pores superficially paired in XVIII close to the lateral margin on round or elliptical porophores (Fig. 4 ). Ampulla ovate to narrowly ovate (Fig. 2 D-F ). Intestinal caeca simple at XXVII.

Variations.

For the A. c. carnosus from China, the number of spermathecal pores and spermathecae are variable: 14 out of 16 specimens typically have four pairs in 5 / 6 / 7 / 8 / 9, one specimen has three pairs in 6 / 7 / 8 / 9 ( LFXHR 7 _ 05), and another one has five pairs in 4 / 5 / 6 / 7 / 8 / 9 ( HNLNR 2 _ 05) (Fig. 2 ). However, despite these variations, molecular analyses have shown them to belong in the same clade with little genetic divergence within the clade (Table 2 , Fig. 1 ). Two specimens from South Korea and one specimen from the USA have three pairs of spermathecal pores in 6 / 7 / 8 / 9 ( Kobayashi 1936; Carrera-Martínez and Snyder 2016). However, prior to this study, no other specimen with five pairs was recorded elsewhere.

Distribution.

China (Liaoning, Beijing, Tianjin, Hebei, Henan, and Shanghai), Japan (Kyushu, Honshu, and Hokkaido), and South Korea (Incheon, Jeju Island).

Remarks.

Detailed descriptions of A. carnosus were reported by Kobayashi (1936), Ohfuchi (1937), and Blakemore (2012, 2013 a, c). Rather than typical closely spaced mid-ventral pre-clitellar genital markings ( Blakemore 2012), widely spaced ones are mostly observed with the A. carnosus specimen from China, which resembles those Hikone specimens from Japan (Tokyo An- 460 - DNA JET- 112) [cf. fig. 3 by Blakemore (2013 a)]. In contrast, the closely spaced pre-clitellar genital markings of the Liaoning specimens (Dandong, DNA 533 R) match those of the South Korean specimen from Geoman ( NIBR IV 261234 - DNA w 37) and the Japanese neotype of A. carnosus (Tokyo An 435) [cf. fig. 2 by Blakemore (2013 a)].

A comparison of characters from the specimens of China, Japan (a neotype NSMT An 435 from the Tokyo Museum) ( Blakemore 2012), and the USA (Kansas) ( Chang et al. 2016) is presented in Suppl. material 1: table S 2. External characters such as the number of spermathecal pores and segment locations of pre-clitellar genital markings match among specimens from different countries. However, internal character variations are observed in the position of the intestinal caeca, which was reported to begin at XXVII and extend to XXIII or XXIV ( Blakemore, 2012; 2013 b; 2013 c; Chang et al. 2016), while the intestinal caeca in the Chinese specimens extends up to XX, XXI (or XXIII) (Fig. 5 ), 2–3 segments more anterior than those from the two previous accounts. Moreover, some character measurements that were not presented in the other two accounts, such as the ventral distances between male pores (0.25–0.29 mm), spermathecal pores (0.28–0.30 mm), and genital markings (latero-ventrally with 0.21–0.29 mm distance apart or mid-ventrally with 0.08 mm distance apart), were added to further aid species identification.

Kobayashi (1936), in his thorough investigation of A. carnosus , presented “ permissible ” variations on the pre-clitellar and post-clitellar genital markings [text-figs. 1–2 in Kobayashi (1936)]. The pre-clitellar genital making variations in the A. c. carnosus from China comply with Kobayashi’s Types IIII, VI, and VIII (see Fig. 3 ), while the post-clitellar genital marking variations comply with Kobayashi’s Types II, IV, and V (see Fig. 4 ). It is important to take note that genital marking patterns can also be considered a distinctive character for species identification (e. g., Nguyen et al. 2020; Aspe et al. 2021).

Figures

Figure 1. The geographical distribution of the A. carnosus complex in eastern Asia and its corresponding phylogenetic tree based on COI using the maximum likelihood method. Color coding: red for China, purple for South Korea, and green for Japan.

Figure 2. Amynthas carnosus carnosus variations on the number of spermathecal pores and spermathecae: four pairs (A, D) (specimen ID 362 R 1 _ 06), three pairs (B, E) (specimen ID LFXHR 7 _ 05), five pairs (C, F) (specimen ID HNLNR 2 _ 05). Scale bars: 1 mm.

Figure 3. Pre-clitellar genital marking (arrows) variations of Amynthas carnosus. A. Modified fig. 1 of the variations of pre-clitellar genital markings from Kobayashi (1936); B. This study. B 1. (specimen ID 362 R 1 _ 01); B 2. (specimen ID 533 R 70 _ 09), and B 3. (specimen ID HNLNR 2 _ 05) comply with the “ permissible variations ” [termed by Blakemore (2012)] of Kobayashi’s (1936) Type III (red), VI (blue), and VIII (green).

Figure 4. Post-clitellar genital marking (arrows) variations of Amynthas carnosus. A. Modified fig. 2 of the variations of post-clitellar genital markings from Kobayashi (1936); B. This study. B 1, B 2. (specimen IDs 362 R 1 _ 07 and HNLNR 2 _ 04); B 3 (specimen ID 362 R 1 _ 04); B 4, B 5. (specimen IDs 362 R 1 _ 01 and 533 R 70 _ 10) comply with the “ permissible variations ” [termed by Blakemore (2012)] of Kobayashi’s (1936) Type II (red), IV (blue), and V (green).

Figure 5. Amynthas carnosus carnosus intestinal caeca showing the segment length variations: A. (specimen ID 533 R 70 _ 10); B. (specimen ID 362 R 1 _ 05), and C. (specimen ID HNLNR 2 _ 05). Scale bars: 1 mm.