Aiyeriella quadritheca Narayanan & Julka, 2025

Narayanan, S. Prasanth, Thomas, A. P. & Julka, J. M., 2025, A new earthworm genus with two new species (Clitellata, Megascolecidae) from the Western Ghats mountain ranges of south-western peninsular India, Zootaxa 5575 (4), pp. 520-534 : 523-524

Aiyeriella quadritheca Narayanan & Julka , sp. nov.

( Figure 1A–D ; 2 )

Type material. Holotype: Clitellate ( ZSIK Reg. No. ZSI/WGRC/I.R.INV.10328), Kottavasal (9°4’17.4” N, 77°12’24.5” E), 13 km from Achankovil and 85 km from Kollam (earlier Quilon), Kollam District, Kerala State, India, 474 m a.s.l., blackish loam soil in evergreen forest, 22 August 2013, collected by S. Prasanth Narayanan, Toms Augustine, S. Arun Sasi, S. Sathrumithra and Dinu Kuriakose. Paratypes. 5 clitellates ( ZSIK Reg. No. ZSI/ WGRC/I.R.INV.10329), same collection data as for holotype .

Other material. 16 specimens altogether. 5 clitellates, 1 aclitellate ( ACESSD /EW/846), between Kumbhavurutty and Kottavasal (9°4’26.7” N, 77°11’26.8” E), Kollam District , Kerala State, India, 241 m a.s.l., disturbed evergreen forest with blackish forest loamy soil with rocks, 23 August 2013, collected by Dinu Kuriakose, S. Sathrumithra, S. Prasanth Narayanan, Toms Augustine and S. Arun Sasi ; 4 clitellates ( ACESSD /EW/847), Pulachippara in Achankovil (9°5’59.9” N, 77°8’46.7” E), Kollam District, Kerala State, India, 288 m a.s.l., deciduous forest near to Tectona grandis plantation, with brownish hard soil, 23 August 2013, collected by S. Arun Sasi, Toms Augustine, Dinu Kuriakose, S. Sathrumithra and S. Prasanth Narayanan ; 4 clitellates ( ACESSD /EW/848), Aluvamkudy (9°16’7.8” N, 77° 0’16.8” E), Pathanamthitta District , Kerala State, India, evergreen forest stream side, blackish brown forest loam, 513 m a.s.l., 21 August 2013, collected by S. Prasanth Narayanan, S. Sathrumithra, Dinu Kuriakose and S. Arun Sasi ; 2 clitellates ( ACESSD /EW/849), Karippanthodu (9°8’55.2” N, 76°52’34.4” E), Pathanamthitta District , Kerala State, India, 421 m a.s.l., Tectona grandis plantation with secondary growth, blackish brown loamy soil, 21 August 2013, collected by S. Prasanth Narayanan, S. Sathrumithra, Dinu Kuriakose and S. Arun Sasi.

Diagnosis. Medium sized worm; length: 117–177 mm, width: 2–3 mm, 115–297 segments. Colour: light brown (unpigmented). First dorsal pore at 5/6. Clitellum annular, in segments 14–17 (= 4). Combined male and prostatic pores, paired, slightly median to a setal line, at posterior ends of fine seminal grooves on segment 18, just anterior to intersegmental furrow 18/19. Female pore single, median, presetal on segment 14. Spermathecal pores two pairs, close to midventral line, at the anterior margins of segments 8 and 9. Genital markings and penial setae absent. Gizzard muscular, barrel-shaped, in segment 5; intestine begins in segment 16. Last pair of hearts in segment 13. Holandric; testis and male funnels free, in segments 10 and 11; seminal vesicles paired, in segments 11 and 12. Prostates paired, tubuloracemose, strap-shaped, in segments 18–21, 22. Spermathecae two pairs, in segments 8 and 9, each with a shortly stalked club-shaped ectal diverticulum; duct about two-thirds the combined length of ampulla and duct.

Description. External. Body light brown, anterior end truncate. Dimensions: Holotype: length: 171 mm, width: 2.5 mm at segment 13, 263 segments; paratypes: length: 117–177 mm, width: 2–3 mm at segment 13, 115–297 segments. Prostomium proepilobic, retracted. First dorsal pore at intersegmental furrow 5/6. Setae lumbricine; setal formula aa = 2 ab = 0.57–0.8 bc = 0.88–1.33 cd = 0.33–0.4 dd at segment 12, aa = 1.75–2.5 ab = 0.77–1.11 bc = 1.75–2.5 cd = 0.20–0.27 dd at segment 24. Clitellum annular in segments 14–17 (= 4); intersegmental furrows indistinct; dorsal pores occluded. Male genital field with a medium-deep longitudinal depression, occupying one-third of segment 17 and whole of segment 18; depression bordered by longitudinal ridges ( Fig. 1A ). Combined apertures of male and prostatic ducts, paired, minute, slightly median to a setal line, at posterior ends of fine seminal grooves on segment 18, just anterior to intersegmental furrow 18/19; each seminal groove extends posteriorly, slightly diverge at about one third of segment 18 and converge posteriorly ( Fig. 1B ). Female pore minute, single, on midventral line, presetal on segment 14. Spermathecal pores tiny, paired, between setal lines aa, close to midventral line, at anterior margins of segments 8 and 9, just behind intersegmental furrows 7/8 and 8/9. Genital markings absent. Penial setae absent.

Internal. Unpigmented. Septa 5/6 delicate, 6/7/8/9 muscular, 9/10–12/13 slightly muscular. Gizzard well developed, muscular, barrel-shaped, in segment 5; oesophagus tubular, calciferous glands absent; intestine begins in segment 16; intestinal caeca, supraintestinal glands and typhlosole absent. Dorsal and ventral blood vessels unpaired and complete; supra esophageal vessel single, in segments 7–13; paired extra oesophageal vessels median to hearts, in segments 5–13; latero-parietal vessels, paired, recognizable in 14–19 segments, turning upward along anterior face of septum 13/14 to join extra oesophageal vessels in segment 13. Last pair of hearts in segment 13. Holandric; testis and male funnels (iridescent) paired, free, in segments 10 and 11; seminal vesicles paired, grape-like, in segments 11 and 12, those of 12 large. Ovaries paired, each with several egg strings in segment 13; ovisacs paired, in 14. Prostates paired, tubuloracemose, elongated, strap-shaped, constricted by septa, in segments 18–21, 22; prostatic duct muscular, S-shaped, narrowed before entering the parietes ( Fig. 1C ). Spermathecae paired, in segments 8 and 9, each with a shortly stalked club-shaped ectal diverticulum (iridescent); duct longer than spermathecal diverticulum ( Fig. 1D ). Meronephric; paired tufts of astomate, micromeronephridia with ducts in sheaves; larger enteronephric tufts in segment 5 with ducts discharging into pharynx and in segment 6 with ducts extends anteriorly, discharging into buccal cavity in segment 2; smaller astomate, exonephric tufts in segments 7–15, discharging through composite ducts in their respective segments; astomate, exonephric clusters of 14–17 micromeronephridia on the body wall in segments 16–18; transverse band of 10–12 astomate exonephric micromeronephridia on body wall, just posterior to septa on segment 19 and posteriad segments, one band at ac setal lines and the other just lateral to d setal line ( Fig. 2 ).

Etymology. The specific epithet ‘ quadritheca’ is a combination of two Latin words, ‘ quadri ’ and ‘ thecae ’, which means “four thecae”. It denotes the condition of four spermathecae in the species.

Ingesta. Mineralized soil, silt (alluvium), pieces of quartz, mica, and very little organic matter.

Habitat. Evergreen forest, deciduous forest, and Tectona grandis plantation with secondary growth. The collection sites have blackish or brownish forest loamy soil.

Ecology. Appears to be endogeic, as indicated by few organic particles and a large quantity of mineralized soil in the intestine. It was found associated with the endemic native Moniligaster blakemorei Narayanan & Julka, 2021 , M. deshayesi Perrier, 1872 , M. keralensis Narayanan & Julka, 2021 , and exotic invasive Pontoscolex corethrurus ( Müller, 1857) and Metaphire houlleti ( Perrier, 1872) earthworm species at various collection sites.

Distribution. India: Kerala: Pathanamthitta District:Aluvamkudy, Karippanthodu; Kollam District: Kottavasal, between Kumbhavurutty and Kottavasal and Pulachippara. This species is widely distributed in the hilly regions.

Remarks. Aiyeriella quadritheca Narayanan & Julka sp. nov. can be easily distinguished from the only other known species of the genus, Aiyeriella longiprostata Narayanan & Julka sp. nov. (described elsewhere in this paper) by the body dimensions (length: 117–177 mm, width: 2–3 mm, 115–297 segments vs length: 72–78 mm, width: 1.5–2 mm, 144–166 segments), number of spermathecal pores (2 pairs vs 1 pair), characteristics of the male field, segmental origin of intestine (origin in segment 16 vs 17), extension of prostates in segments (extending to segments 21–22 vs 20–27, 30).

Figures

FIGURE 1. Aiyeriella quadritheca Narayanan & Julka, sp. nov., A. Ventral view of anterior region. B. Male genital field of a relaxed specimen, enlarged ventral view. C. Prostate, side view, right side. D. Spermathecae, dorsal view, left side. Cl—Clitellum, Fp—Female pore, Mf—Male genital field, Pd—Prostatic duct, Pr—Prostate, Sa—Spermathecal ampulla, Sd—Spermathecal duct, Sdi—Spermathecal diverticulum, Sg—Seminal groove, Sp—Spermathecal pore, Vd—Vasa deferens.

FIGURE 2. Aiyeriella quadritheca Narayanan & Julka, sp. nov., nephridial condition posterior to segment 19, right side, dorsal view. Ne—Nephridia.