Glyphidrilus gatesi, Shen & Yeo, 2005

Shen, Huei-Ping & Yeo, Darren C. J., 2005, Terrestrial Earthworms (Oligochaeta) From Singapore, Raffles Bulletin of Zoology 53 (1), pp. 13-33 : 16-18

Glyphidrilus gatesi , new species

( Fig. 1 )

Glyphidrilus sp. Gates, 1938: 221.

Material examined. – Holotype – 1 mature (clitellate), amputated specimen (dissected)( ZRC 1974.12.2.51), Sungei Kayu , swamp forest near River Sedili, Johore, Malaysia, Feb.1937.

Paratypes – 9 mature and 2 immature specimens (7 mature and 1 immature specimens amputated; one of the amputated mature specimens dissected by Gates with parts of the digestive tract and blood vessels removed) together with three body fragments in the bottle ( ZRC 1974.12.2.52-62) .

Description. – Length 46+ mm, segments numbering 65+ for holotype. For two intact mature specimens (one nearly broken between segment 42/43, the other macerated), 95 mm and 83 mm in length, and 122 and 119 in segment number. For the other seven amputated mature specimens, 34-65 mm in length, and 42-90 in segment number. Wing width for mature specimens 2.1-3.0 mm. For two aclitellate specimens, 115 mm and 70 mm in length, and 262 and 157 in segment number. Prostomium zygolobous. Dorsal pores absent. Clitellum from XVII, 1/2XVII or XVIII to XXV, 1/2XXVI or XXVI. Wings lateral to b, from posterior XVIII or 18/19 to 1/2 XXIV, or entire segment XXIV. Setae paired, preclitellum: aa = 2ab, bc = 1.47cd, aa = 0.88dd; postclitellum: aa = 2.57ab, bc = 2cd, aa = 0.62dd. Preserved specimens brown in colour with yellowish clitellum.

Female pores inconspicuous on XIV, in line with b near 13/ 14 segmental furrow. Male pores and spermathecal pores not visible. Genital papillae postsetal (except one mature specimen with presetal genital papillae in XXIV-XXVI); lateral series paired or asymmetrical, lateral to b or medial to c on XV-XVIII, in line with b or lateral to b or medial to c on XXIV-XXVI; unpaired median series between aa on XIII-XIX and XXIV-XXVII; number and position variable among specimens. For 10 mature type specimens examined, prewing lateral papillae on XVII for 1 specimen, XVII-XVIII for 4 specimens, XVI-XVIII for 1 specimen, XV-XVIII for 3 specimens, not recognizable for 1 macerated specimen; prewing median papillae absent from 1 specimen, present on XIII-XVIII for 1 specimen, XIV-XVII for 1 specimen, XIV-XVIII for 1 specimen, XIV-XIX for 1 specimen, XV-XVIII for 2 specimens, XV-XIX for 1 specimen, XVI-XVIII for 2 specimens; postwing lateral papillae on XXIV for 2 specimens, XXV for 1 specimen, XXIV-XXV for 1 specimen, XXIV-XXVI for 5 specimens, not recognizable for 1 macerated specimen; postwing median papillae absent from 4 specimens, present on XXIV for 1 specimen, XXIV-XXVI for 1 specimen, XXIV-XXVII for 2 specimens, XXV-XXVI for 1 specimen, not recognizable for 1 macerated specimen. Each papilla round, prewing papillae 0.4-0.5 mm and postwing papillae 0.3-0.35 mm in diameter .

Gizzard mainly in VIII. Intestine enlarged from XVIII. Dorsal blood vessel aborted anterior to segment IX. Hearts IX-XI. Nephridia holoic. Seminal vesicles four pairs in IX-XII: smallest in X, large in XI, and largest in XII occupying two segments. Testes shiny in X and XI. Prostate and accessory glands absent. Spermathecae sessile, elongated oval or globular, 0.35-0.45 mm long, three on each side per segment in XV-XVII.

Etymology. – The name “ gatesi ” is given to this species in honor of Dr. Gordon Enoch Gates who made great contributions to taxonomy and systematics of earthworms, particularly of South and Southeast Asia, and described the collection (ZRC 1974.12.2.51-62) as an anonymous species ( Glyphidrilus sp. )( Gates, 1938).

Remarks. – For mature Glyphidrilus specimens, genital papillae are always present on the segments or adjacent segments where wings begin and end. The presence of genital papillae in the middle of the wing region is rare. Therefore, the position of genital papillae shows some association with location of wings. The presence or absence of median (medio-ventral) papillae has been used as one of the key characters for species identification ( Gates, 1958; Chen & Xu, 1977), but this character is highly variable among individuals. For example, four of the 10 mature specimens of G. gatesi lack postwing median papillae. The position of wings is less variable among specimens as compared to genital papillae ( Gates, 1958), and is perhaps a more reliable external character for species distinction (see Table 3).

Glyphidrilus gatesi , new species, is similar to Glyphidrilus spelaeotes ( Stephenson, 1924) from Assam, India in the location of wings (see Table 3). The position and arrangement of genital papillae are highly variable in both species so that they are not used for the distinction between the two species. G. gatesi has a clitellum from XVII or XVIII to XXV or XXVI, three pairs of hearts in IX-XI, and three spermathecae on each side per segment in XV-XVII, whereas G. spelaeotes has a longer clitellum in XVI-XXX, four pairs of hearts in VIII-XI, and four to five spermathecae on each side per segment in XIV-XVI (see Table 3).

Glyphidrilus gatesi differs from Glyphidrilus malayanus

( Michaelsen, 1902), the only species of this genus reported from the Malay Peninsula, by having wings extending from XVIII or XIX to 1/2XXIV or XXIV, three spermathecae on each side in XV-XVII and four pairs of seminal vesicles in IX-XII, whereas the latter has wings from XVII or XVIII to 1/3XXI or 1/3XXII, spermathecae in XIV-XVI and two pairs of seminal vesicles in XI-XII (see Table 3).

Figures

Fig. 1. Glyphidrilus gatesi, new species, holotype (46+ mm). A, right latero-ventral view of wings and genital papillae (gp); B, left lateral view of wings and genital papillae.