New species and new records of earthworms of the genus Drawida from Kerala part of the Western Ghats biodiversity hotspot, India (Oligochaeta, Moniligastridae)

Abstract Two new species of Drawida Michaelsen, 1900, namely Drawida polydiverticulata Narayanan & Julka, sp. n. and Drawida thomasi Narayanan & Julka, sp. n., are described from material collected from the Indian state of Kerala, which lies in the Western Ghats biodiversity hotspot. Drawida elegans Rao, 1921, Drawida kanarensis Stephenson, 1917, Drawida modesta Rao, 1921, Drawida somavarpatana Rao, 1921, and Drawida thurstoni Gates, 1945 are recorded for the first time from the state.


Introduction
Kerala is a narrow coastal equatorial tract of India (between 8°17'-12°47'N and 74°52'-77°24'E). The steep sloping land of Kerala along the southwest corner of the Indian Peninsula has its own unique identity (Nair 2011). The dominating surface feature of the state is the Western Ghats, which is one of the eight 'hottest hotspots' of biodiversity in the world (Myers et al. 2000, Mittermeier et al. 2011. In a broad generalized approach, Kerala can be divided into three distinct physiographic regions, namely the coastal lowlands (< 75 m a.s.l.), midlands (75-500 m a.s.l.), and high ranges (500-2000 m a.s.l.) (Iype et al. 1991). The area experiences two rainy seasons, viz., the southwest monsoon (June to September) and northeast monsoon (October to November). Annual rainfall ranges from 1,520 to 4,075 mm, but it may be as high as 6,000 mm in certain pockets and as low as 600 mm in rain shadow areas (KSCSTE 2007). The general climate is mostly tropical but tends to be temperate in high mountainous areas (average temperature 19°C-37°C; minimum 0°C in high ranges). Major forest types are tropical evergreen and semi evergreen, tropical moist and dry deciduous, mountain 'sholas', grasslands and low land scrub jungles (Islam and Rahmani 2004).
A great variety of vegetation coupled with high rainfall and moderate temperature has created a cradle for earthworm diversity in Kerala, which harbours about 21% of country's known earthworm species (Narayanan et al. 2016). It is noteworthy that Kerala also possesses about 40% of earthworm species found in the Western Ghats that constitute India's mega earthworm diversity area with 200 species (Julka and Paliwal 2005, Julka et al. 2009, Narayanan et al. 2016) of the 505 species from the Indian region (Blakemore 2007).
Several species in Kerala are known only from the original description, and most of them were recorded more than 80-90 years ago (Narayanan et al. 2016). Hence, we conducted extensive survey of earthworms in diverse habitats in the coastal areas, midlands and various types of forests in the hilly regions of the state. This has revealed the presence of two new species and five new records of the genus Drawida Michaelsen, 1900. The details of the two new species Drawida polydiverticulata sp. n. and Drawida thomasi sp. n. and the newly recorded Drawida elegans Rao, 1921, Drawida kanarensis Stephenson, 1917, Drawida modesta Rao, 1921, Drawida somavarpatana Rao, 1921, and Drawida thurstoni Gates, 1945 are dealt with in this paper.

Materials and methods
Earthworms were obtained from soil by digging and hand sorting methods, and also searching organic microhabitats such as fallen tree trunks and leaf litter. Specimens were fixed in 5% formalin and subsequently transferred to ethanol. All anatomical observations were made by dissection under a stereomicroscope (Nikon SMZ800N), and illustrations were made by the attached drawing tube. Holotype and paratype specimens of the new species have been deposited at Zoological Survey of India, Western Ghats Regional Centre (ZSI-WGRC), Kozhikode (Calicut), Kerala, India. Other specimens are housed in Advanced Centre of Environmental Studies and Sustainable Development (ACESSD), Mahatma Gandhi University, Kottayam, Kerala, India. each pore at centre of oval porophore at about mid bc (Fig. 1A, B). Genital markings absent. Nephridiopores present from segment 3, aligned with setae d.
Etymology. The specific epithet 'polydiverticulata' is after multi-lobed condition of spermathecal atrium.
Ingesta. Coagulum comprising of mineralized soil, rootlets, tiny pieces of bark and leaves.
Habitat. Shola forest in vicinity of streams; near to stagnant pools or streams in grass lands.
Remarks. Drawida polydiverticulata sp. n. is distinguishable from all the known species of the genus in having spermathecal atrium with more than two lobes. In one specimen from Pettymudy, spermatheca on right side with one branch of atrium along with lobes extends to segment 8. Diagnosis. Length 55-66 mm, diameter 4.5 mm, segments 66-105. Colour bluish. Male pores in 10/11, large transverse slits, slightly lateral to b lines. Spermathecal pores in 7/8 at c lines. Genital markings absent. Gizzards number 3 in 15-17. Coiled vas deferens mass as large as testis sac; vas discharging directly into prostate dorsally at about its middle. Prostates glandular tubular, slightly bent, prostatic capsule tubular, bent entally. Spermath- ecal atria bilobed, one lobe in segment 7 and the other in segment 8; atrial lobes tubular, very long, 9-10 mm in length, coiled into compact masses. Nephridiopores aligned with d.

Holotype
Setae on left side Setae on right side setae on the left side setae on the right side lines. Genital markings absent. Nephridiopores, present from segment 3, aligned with setae d. Septa 5/6/7/8/9 slightly muscular. Gizzards 3 in segments 15-17 (holotype and paratypes); intestine begins in segment 24. Last pair of hearts in segment 9; commissures of extra oesophageal vessel present on posterior face of septum 8/9, not recognizable on posterior face of 9/10. Testis sacs paired, in segments 9 and 10, extending to segment 15 on left side and to segment 17 on right side; vas deferens long, coiled in hairpin loops, aggregated into a mass as large as testis sac, discharging directly at about middle of dorsal face of prostate. Prostates paired, glandular, tubular, slightly bent at ental end (Fig. 3B); prostatic capsule shining, smooth, tubular, slightly bent entally (Fig. 3C); prostatic duct about half as long as gland, thick, slightly narrowed before entering parietes. Spermathecae paired, in segment 8; atrium bilobed, one lobe in segment 7 and the other in segment 8, each lobe tubular, very long and coiled into a compact mass occupying entire body cavity of respective segment, 9-10 mm long (when uncoiled); spermathecal duct short with a few coils entering at junction of two atrial lobes (Fig. 3D) Distribution. Known only from the type locality (Fig. 2). Ingesta. Mostly silt, with tiny pieces of mica and organic material. Biology. Autotomy is very common. Infested with nematodes in the region of reproductive system.
Habitat. Bushes with grassy under growth, loamy soil, rich in organic matter, by the side of tuber cultivated field earlier used for coffee plantation.
Remarks. Range of the length, diameter, and number of segments in the Kerala specimens are 83-117 mm, 5-6 mm, and 161-171 respectively. Three gizzards in the present specimens in segments 12-14. Mass of vas deferens loops is shorter than testis sac.
Remarks. Range of the length, diameter, and number of segments of the Kerala specimens are 38-51 mm, 3 mm, and 166-177 respectively. Gizzards are in segments 14-17.
Biology. Spermathecae and male genitalia are absent in a number of worms from Kerala, indicating parthenogenetic mode of reproduction.
Remarks. The diagnosis is based on the present material from Kerala, description as given by Stephenson (1923) and re-examination of type material in Zoological Survey of India, Kolkata (Reg. no. W416/1). Worms from Kerala are longer and stouter, and have a greater number of gizzards than worms from Karnataka (Rao 1921). Body dimensions and number of gizzards in Kerala worms are: average length 94.61 mm (range = 82-133 mm; n =13); average width 5.38 mm (range 5-6 mm; n = 17); average number of segments 128.23 (range 111-154; n = 13), gizzards 3-5, mainly located between segments 15-20 (Table 4).
Remarks. Range of the length, diameter, and number of segments of the Kerala specimens are 171-176 mm, 7.5-8 mm, and 183-185 respectively.

Discussion
Earthworms of the primitive family Moniligastridae are believed to have originated somewhere in the region of Malaya Archipelago (Gates 1972, Blakemore et al. 2014Jamieson (1977) suggests their origin near Myanmar. Its natural range encompass, south, southeast and east Asia, from peninsular India to Japan through Myanmar, China, extreme southern portion of Far East Russia, Korea, the Philippines, Borneo, and Sumatra (Gates 1972). The large range is primarily due to the spread of Drawida, the most speciose moniligastrid genus that presumably colonized peninsular India after the collision of Indian plate with Asia during Caenozoic period (Gates 1972, Blakemore et al. 2014. Recent attempts to resolve conflicts within the taxonomy of the genus have used molecular mtDNA barcoding, where possible of primary types (Blakemore et al. , 2014. Drawida has undergone extensive radiation in India with 72 species listed by Blakemore (2007) but its greatest concentration (43 species) is found in the Western Ghats (Stephenson 1923, Gates 1945. Within the Western Ghats, the genus has an important centre of speciation in the southernmost state of Kerala, most species being endemic; there are 16 species, ten of which are endemic (Narayanan et al. 2016). The present discovery of two new species and five new records of Drawida further contribute to the vast species richness of the genus in the state.