Metaphire bununa var. glareosus, Tsai & Tsai & Liaw, 2000

Tsai, C. - F., Tsai, S. - C. & Liaw, G, 2000, Two new species of protandric pheretimoid earthworms belonging to the genus Metaphire (Megascolecidae: Oligochaeta) from Taiwan, Journal of Natural History 34, pp. 1731-1741 : 1738-1740

Metaphire bununa var. glareosus subsp. nov.

Type material

HOLOTYPE: A mature specimen collected 20 March 1998 from Taiwan Forest Recreation Park at the east side of Central Mountain Ridge , Chupun, Taitung Prefecture (®gure 1) by C. S. Lu, a park ranger (coll. no. 1998-18).

PARATYPES: Two mature specimens (one amputated, dissected; same collection of holotype).

Other material

A mature specimen (330 mm, dissected) collected 21 September 1998 at the type locality by C. S. Lu (coll. no. 1998-63).

Characters

The subspecies glareosus is distinguishable from var. typica by having fewer setae, segments and annulets, and in the presence of seminal vesicle vestiges in XII and wrinkled caecae ( table 2). On the other hand, glareosus shares most of its characters with typica: C-shaped male pore, four pairs of spermathecae in VI ±IX with their pores in 5/6±8/9, no genital papillae in the male pore and spermathecal pore regions, a pair of testis sacs in X, a pair of seminal vesicles in XI, septa 8/9 and 9/10 absent and 10/11 and 12/13 greatly thickened, gizzard round in VIII±X, and racemose prostate glands with slightly curved duct.

Locality and habitat

Type locality was at the mountain slope where soil was composed primarily of small gravel and sand covered with grasses. Intestines of the type specimens were ®lled with sand and small gravel visible outside the bodies.

Remarks

Metaphire bununa sp. nov. is one of the largest hill-dwelling pheretimoid earthworms in Taiwan. Its large size, octothecae and absence of genital papilla are shared by Amynthas yushi ( Tsai, 1964) and Amynthas formosae ( Michaelsen, 1922) of Taiwan and Metaphire riukiuensis ( Ohfuchi, 1957) of the Riukiu Islands. The close resemblance in external features between M. riukiuensis and A. formosae was noted by Ohfuchi (1957). However, with the presence of copulatory pouches, M. bununa of Taiwan is more closely related to M. riukiuensis of the Riukiu Islands than to A. yushi and A. formosae of Taiwan. Metaphire bununa sp. nov., particularly its subspecies glareosus subsp. nov., shares most characters with M. riukiuensis ( table 2). The primary diOEerence between the two species is that M. bununa is protandric, while M. riukiuensis is holandric ( Ohfuchi, 1957).

With respect to octothecae and protandry, M. bununa shares these characters with M. stephensoni (Michaelsen) of southern Indochina ( Michaelsen, 1934). However, M. stephensoni is small (65 mm) and has a transverse-ova l male pore and genital papillae, and is easily distinguishable from M. bununa ( table 2).

Ohfuchi (1957) indicated that the setal number of M. riukiuensis gradually increases in anteclitellar segments but suddenly decreases in XX (72±74 in VII and 48±51 in XX). He further stated that this tendency is usually observed in earthworms in South Sea islands but not in Japanese species. In M. bununa and M. paiwanna in Taiwan, the setal number gradually increases in the head region, but unlike M. riukiuensis the number remains as high as or slightly increases in XX ( tables 1, 2). For the 266 mm specimen of M. bununa typica (coll. no. 199-21) which has 221 segments, the setal numbers are 103 in V, 114 in VII, 125 in XX, 132 in C and 111 in CC. Apparently, the setal number seems to be species-speci®c, and there is no tendency to a sudden decrease in XX for M. bununa and M. paiwanna in this study.

Three mature specimens (coll. no. 1999-2) have a vestige of a horizontal ridge in the male pore region, barely visible under the dissection microscope. It extends from XVIII setal line to the posterior end of the male pore, instead of extending to the middle of the male pore as in M. paiwanna (®gures 2A, B, 3A). In addition to this character, M. bununa shares protandry and octothecae with M. paiwanna , suggesting the close phylogenic relationship between the two species.

The species name `bununa ’ is given with reference to the native` Bunun tribe’ living in Nantou, Taiwan. The subspecies name `glareosus ’ is given to indicate the habitat of its type locality .

Two geographical subspecies were identi®ed for both M. paiwanna sp. nov. and M. bununa sp. nov. in Taiwan. Typica of both new species occur on the west side of the Central Mountain Range, whereas the subspecies liliumfordi of M. paiwanna and the subspecies glareosus of M. bununa occur on the eastern side of the range (®gure 1). Apparently, the Central Mountain Range which runs from north to south in the middle of the island is an important mechanism (geographical barrier) for the allopatric subspeciation of the two species.