Aiyeriella Narayanan & Julka, 2025

Genus Aiyeriella Narayanan & Julka gen. nov.

Diagnosis. Setae lumbricin. Combined male and prostatic pores, paired at posterior ends of fine seminal grooves on segment 18. Single large oesophageal gizzard, in segment 5; oesophageal calciferous glands or calciferous dilations absent; supra-intestinal glands, typhlosole, and intestinal caeca absent. Micromeronephridia astomate, exonephric paired tufts in 2–10; several avesiculate, exonephric on the body wall in 11, and posteriad segments. Prostates tubuloracemose, elongated, strap-shaped, paired. Penial setae absent.

Etymology. Aiyeriella , gender feminine, is named after the late Prof. K.S. Padmanabha Aiyer for his significant contributions to the taxonomy of earthworms in Kerala State, India, in the first half of the 20th century

Type species. Aiyeriella quadritheca Narayanan & Julka , gen. et sp. nov.

Description. External. Small to moderate-sized terrestrial earthworms (72–177 mm). Prostomium proepilobic. First dorsal pore in intersegmental furrow (4/5) 5/6. Setae lumbricin. Clitellum annular, on segments 14–17 (= 4); intersegmental furrows distinct or indistinct; dorsal pores occluded. A pair of combined male and prostatic pores at posterior ends of fine seminal grooves, on segment 18 in aa setal lines or slightly lateral to setal lines a. Female pore single, minute, conspicuous, on midventral line, presetal on segment 14. Spermathecal pores, segmental, paired, bithecal, or quadrithecal, at anterior margins of segment(s) 8 or 8 and 9, in a line or between setal lines aa. Nephridiopores not recognizable. Genital markings and 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; calciferous glands, intestinal caeca, supraintestinal glands and typhlosole absent. Dorsal and ventral blood vessels unpaired and complete; supraoesophageal vessel single, in segments 7–13; paired extra-oesophageal vessels median to hearts, in segments 5–13; lateroparietal vessels, paired, recognizable in 14–19 segments, turning upward along the anterior face of septum 13/14 to join extra-oesophageal vessels in segment 13. Last pair of hearts in segment 12 or 13. Nephridia meronephric, micromeronephridia astomate, exonephric paired tufts in segments 2–10, several avesiculate, exonephric on the body wall in segment 11, and posteriad segments. Holandric; testis and funnels paired, free, in segments 10 and 11; seminal vesicles paired, in segments 11 and 12, those of 12 larger. Ovaries paired, in segment 13; ovisacs paired, in segment 14. Prostates paired, tubuloracemose, elongated, strap-shaped, prostatic duct muscular, vasa deferentia joining the prostate ducts entally at the glandular portion. Spermathecae each with a single, unilocular, diverticulum.

Distribution. Western Ghats of Pathanamthitta, Kollam, and Thiruvananthapuram districts of the Kerala state in the south-western portion of peninsular India.

Remarks. Aiyeriella gen. nov., falls in an Indomalayan group of meronephric megascolecid genera with lumbricin arrangement of setae, combined male and prostatic pores on segment 18, an oesophageal gizzard anterior to septum 5/6, without intestinal caeca, typhlosole, calciferous and supra-intestinal glands, prostate tubuloracemose, strap-shaped, and lacking stomate mega- and micromeronephridia in segments posterior to clitellum. The most similar genera to Aiyeriella gen. nov., are Lennoscolex Gates, 1960 and Comarodrilus Stephenson, 1915 .

The genus Lennoscolex Gates, 1960 , has a complicated taxonomic history. Gates (1960) erected Lennoscolex , with Woodwardiella pumila Stephenson, 1931 as the type species from the Bhamo of Burma (now Myanmar). Gates (1972) stated that, its simplicity in the digestive system (perhaps primitive?) with a highly advanced sort of meronephry of the excretory system made this genus phylogenetically interesting. Nevertheless, Gates (1972) mentioned that the definition of this genus is incomplete. In the same works ( Gates 1960, 1972), he suggested that south-western Indian species, such as, Notoscolex tenmalai ( Michaelsen, 1910) , N. minimus Aiyer, 1929 , N. peermadensis Aiyer, 1929 , N. travancorensis Aiyer, 1929 , and Notoscolex kayankulamensis ( Aiyer, 1929) , appeared to be the possible candidates for inclusion in the genus. But he did not include them, because all these species needed accurate characterization of vascular, excretory, digestive systems, and prostate glands ( Gates 1972). The recent global checklist of earthworms by Brown et al. (2022) does not consider Lennoscolex as a valid genus, and the two species included in the genus are kept under Woodwardiella Stephenson, 1925 . Gates (1972) stated that the genus Woodwardiella is purely of Australian origin. However, according to Jamieson (2001), it is uncertain that the species credited to the genus Woodwardiella from south ( India and Sri Lanka) and southeast Asia ( Burma = Myanmar and Java Island of Indonesia) are congeneric with the Australian type species. Later, Blakemore (2013) affirmed that the Indian and Sri Lankan Woodwardiella species were moved to meroic Notoscolex and/or to Lennoscolex . The above-mentioned south-western Indian species of Notoscolex are retained under the genus Notoscolex Fletcher, 1886 (sensu lato) by Narayanan et al. (2016, 2023a). Jamieson (2001) stated that the Woodwardiella species from Australia had the following excretory system “nephridia exonephric, stomate, avesiculate holonephridia forming a single series on each side in c lines but (always?) replaced in anterior segments by tufts discharging into the buccal cavity or exonephrically in d lines”. But as per Gates (1972), in Lennoscolex it is “meroic, (in anterior segments?), behind the clitellum with one pair per segment of clusters of four to six small, exoic and astomate, parietal, and avesiculate nephridia”. Hence, based on the key difference in the condition of the excretory system, herein the genus Lennoscolex is revived as a valid genus with two species assigned to it by Gates (1960), namely, L. javanica and L. pumila .

Comarodrilus Stephenson, 1915 is a monotypic genus known only from the original description of C. gravelyi Stephenson, 1915 . However, it is a poorly understood genus, and we were unable to find any individuals of it in our latest collections at the type locality. According to Gates (1972), it has racemose prostates and so belongs in the Megascolecidae . Further, he added that so little is known about somatic anatomy that the status of the genus and relationships of C. gravelyi are not determinable. Even so, at present, the genus Comarodrilus is regarded as a valid genus assigned in the family Megascolecidae in the recent global checklist of earthworms (Brown et al. 2022) as well as in the Kerala ( Narayanan et al. 2016) and Indian checklists ( Narayanan et al. 2023a), Aiyeriella , gen. nov., can be distinguished from the closely related Indomalayan genera, such as Lennoscolex and Comarodrilus , by the characters given in Table 1 View TABLE 1 .