Amynthas aeruginosus Kinberg, 1867

Bantaowong, Ueangfa, Somniyam, Pattana, Sutcharit, Chirasak, James, Samuel W & Panha, Somsak, 2014, Four new species of the earthworm genus Amynthas Kinberg, 1867, with redescription of the type species (Clitellata: Megascolecidae), Raffles Bulletin of Zoology 62, pp. 655-670 : 656-658

Amynthas aeruginosus Kinberg, 1867

( Fig. 2 )

Amyntas aeruginosus Kinberg, 1867: 101 . Type locality: Guam, sub

lapidibus prope rivulum. Michaelsen, 1899a: 434–437, fig. 2.

Michaelsen, 1899b: 4. Perichaeta aeriginosus: Beddard, 1891: 278 . Pheretima aeruginosa: Michaelsen, 1900: 253 . Amynthas aeruginosus: Sims & Easton, 1972: 211 .

Material examined. A holotype was not designated, and the original description was based on more than one specimen (see Kinberg, 1867: 101; Michaelsen, 1899a). The syntype lot from the Swedish Museum of Natural History consists of 4 specimens in ethanol. The complete and sexually mature specimen, which is similar to the original description and a later description in Michaelsen (1899a: 434, fig. 2) is designated here as the lectotype SMNH 154.1 ( Figs. 2A–C ). The other three specimens, two complete and immature, and one fragmented and mature specimen from the same lot are recognised as the paralectotypes SMNH 154.2. In addition, we examined one specimen originally from the Kinberg type series, which was examined by Michaelsen (1899a: 434) and housed in Biozentrum Grindel und Zoologisches Museum, University of Hamburg. It is now recognised as paralectotype ZMH V 5221 ( Figs. 2D–F ). This designation is to preserve the stability of the name and verify the unique characters of the type species, which were not mentioned in the original description.

Diagnosis. Quadrithecal with spermathecal pores in 7/8/9. Male pores paired, superficial in segment XVIII, each pore situated in the center of small round flat disc, genital markings lacking. Each spermatheca a large transversely oval sac and tubular diverticulum, its proximal end with a neck–like constriction. Intestinal caeca simple. Multilobed prostate gland with stout duct.

Description of lectotype. Dimension; 95 mm by 4.5 mm at segment X; body cylindrical with 99 segments. Setae regularly distributed around segment equators, numbering 49 at VIII, 57 at XX, 4 between male pores, setae formula AA:AB:ZZ:ZY=1.3:1:1:1 at XIII. Clitellum annular XIV– XVI, setae absent. Single female pore at XIV. Prostomium epilobic. Male pores are superficial in segment XVIII, 0.17 circumference apart ventrally; distance between male pores 2.5 mm, each pore situated in the center of small round flat disc. Genital markings absent. Spermathecal pores two pairs in 7/8–8/9, 0.16 circumference apart ventrally, distance between spermathecal pores 2.3 mm.

Septa 5/6–7/8 thick, 8/9–9/10 absent, 10/11–11/12 thin. Gizzard large behind 7/8, intestinal origin XV; the intestinal caeca originate in XXVII, simple and extend anteriorly to XXV. Typhlosole rudimentary. Lymph glands not observed. Oesophageal hearts four pairs in X–XIII. Holandric; testes and funnels in X and XI. Seminal vesicles paired in XI– XII. Prostate glands paired in XVIII, multi-lobed radiating fan-like from ental end of prostatic duct; ducts stout, thick muscular. Ovaries in XIII. Spermathecae two pairs in VIII and IX, ampulla large sac-shaped, diameter slightly greater than ampulla axis length, with a stout stalk, as long as ampulla. Diverticulum tubular, its proximal end with a neck-like constriction and iridescent.

Variation. The lectotype measures 95 mm body length, with 99 segments; the body lengths of four paralectotypes are 84, 85, 92, 100 mm, with 92, 94, 95, 96 segments.

Remarks. Michaelsen (1899a) records the history of A. aeruginosus type series, which comprises five spirit-preserved specimens. The adult and complete syntype specimen was examined and was used for the re-description of internal characters, but it was not designated as a lectotype ( Michaelsen, 1899a; ICZN, 1999). We have examined all the type specimens and found that the pseudohearts and gizzard of Michaelsen’s dissected specimen were missing. Therefore another complete adult specimen of Kinberg’s collection is here designated as the lectotype.

The description and measurements given herein are in agreement with those of Kinberg (1867) and Michaelsen (1899a). However, the species description published by Sims & Easton (1972) is slightly incongruent by having genital markings and 0.22 circumference apart ventrally of male pores. This difference is clear due to an expansion of the description to include another two nominal species, A. upoluensis ( Beddard, 1887) and A. rennellanus ( Gates, 1959) , which were recognised as junior synonyms (see Sims & Easton, 1972; Lee, 1981). Currently, these two nominal species are widely accepted as separate species ( Michaelsen, 1913; Gates, 1937, 1959; Blakemore, 1997). Amynthas rennellanus differs from A. aeruginosus by having single, presetal genital markings in some of IX–XI and XVII–XXI while, A. upoluensis from Western Samoa is distinct from A. aeruginosus in the presence of genital markings on VII–VIII and XVII–XIX.

Amynthas aeruginosus is still known only from the type specimens. Michaelsen (1899a) provided a brief illustration only of a spermatheca, but not other important features such as the male genital field, prostate glands and intestinal caeca. In this study, the completed description with schematic figures of the external ventral view and internal dorsal view are provided.

Figures

Fig. 2. External and internal morphology of Amynthas aeruginosus, the type species. A–C, lectotype (SMNH 154): A, external ventral view; B, internal dorsal view; C, spermathecae. D–F, paralectotype (ZMH V5221): D, spermathecal pores; E, male pores; F, incomplete internal dorsal view.