Main Content
< Top page

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Aporrectodea

Aporrectodea Orley, 1855 (ref. ID; 6916)

Family Lumbricidae (ref. ID; 5925, 6023)

ref. ID; 6916

Besides failing to designate the type species, the material labelled by Eisen (1873) as Allolobophora included A. riparia (now a synonym of A. chlorotica), A turgida (now a synonym of Aporrectodea caliginosa), A. mucosa (now a synonym of Ap. rosea), A. norvegica (now a synonym of Dd. rubidus), A. arborea (now a synonym of Dd. rubidus), A. fetida (now the generotype of Eisenia) and A. subrubicunda (now a synonym of Dd. rubidus). When Omodeo (1956) designated A. chlorotica (Savigny, 1826) as the type of the genus, this resulted in the exclusion of the majority of the species previously attributed to it (Gates 1975). The third potential genus Nicodrilus proposed by Bouche (1972) is considered by Gates (1975) as a junior synonym of the genus Aporrectodea, which has been accepted by a high number of earthworm taxonomists (Easton 1983; Fender 1985; Mrsic 1991; Perel 1997; Zicsi and Csuzdi 1999; Blakemore 2007). However, it is difficult to separate Allolobophora from Aporrectodea on the basis of their morphological characters. The only anatomical difference is the opening of the calciferous sacs into the oesophagus in segment 10 (posterior and equatorially, respectively) and the shape of the nephridial bladders (J-shaped with the ental limb being anterior or J- or U-shaped with the ental limb being posterior) (Gates 1975; Fender 1985; Mrsic 1991; Sims and Gerard 1999). This together with several nomenclature problems associated to the number and validity of the synonyms included highlights the need for a well-defined diagnosis of Aporrectodea (Mrsic 991; Zicsi and Csuzdi 1999; Csuzdi and Zicsi 2003; Blakemore 2007). The twelve species belonging to these three putative genera and investigated in this study appear to be scattered in both trees, reflecting this taxonomical heterogeneity. In the case of the geographically widespread Ap. caliginosa, it is usually considered to comprise a complex or group of species (sensu Blakemore 2007, 2008), namely Ap. caliginosa (Savigny, 1826) (synonym Ap. turgida Eisen, 1873), Ap. trapezoides (Duges, 1828) (synonyms include Nicodrilus caliginosus meridionalis Bouche, 1972), Ap. tuberculata (Eisen, 1874) (synonym: N. c. alternisetosus Bouche, 1972) and A. nocturna Evans, 1946 (synonym: N. nocturns Bouche, 1972). To date there is no consensus on whether they should be ranked as closely-related species or different subspecies or morphs within a single species (Briones, 1996). This taxonomical problem is also aggravated by the fact that the material identified by Eisen as Allolobophora turgida f. tuberculata Eisen, 1874 includes specimens of Ap. trapezoides, Ap. tuberculata, A. nocturna, O. lacteum, O. cyaneum and others (Gates 1972). Similar misidentification situations were detected during a detailed revision of the test material deposited at the Natural History Museum of London and Canadian Museum of Nature in Ottawa (Briones 1991). Not only several labels with different expert opinions were inside the jars but also the same authority corrected its own identification years later. This, together with the fact that the some specimens were immature or badly preserved, made the confirmation of the species' assignments very difficult. However, dissection of some of this material allowed Briones (1991, 1996) to conclude that Ap. tuberculata is a synonym of Ap. caliginosa (see also Gates 1972; Blakemore 2007, 2008). The molecular information obtained in this study show that this complex of species appears to constitute a group with some support, with A. caliginosa (Savigny, 1826) and Ap. tuberculata clearly being very closely related (95% and 100% BS for 16S and COI, respectively), in agreement with their consideration as synonyms (Briones 1991, 1996; see also Blakemore 2007). Furthermore, Ap. longa Ude, 1885, Ap. trapezoides and A. nocturna Evans, 1941 seem to form a clade with moderate support (93% BS for COI but with less than 50% BS for 16S), which agrees with similarities in their morphology (dark brown pigmentation) and ecology (the three species are anecic worms and therefore, they show similar burrowing behaviour and feeding strategies; see also Briones, 1993). Another group with some phylogenetic support is the one formed for A. chlorotica (Savigny, 1826), A. molleri and Ap. icterica, (Savigny, 1826), three endogeic species with the same chromosome number but morphologically very different. Both trees display the close relationship of A. molleri with Ap. icterica with a high bootstrap value for the 16S (99%). Similar arrangements in which A. molleri clusters with Aporrectodea spp. have been observed previously (Pop et al. 2007). Furthermore, A. chlorotica is always in a sister-group position to this group with moderate confidence (76% and 53% BS for 16S and COI, respectively) adding more doubts about the phylogenetic separation of Aporrectodea from Allolobophora. Interestingly, the two colour morphos of A. chlorotica (green and pink based on the presence/absence of a bilin pigment Sims and Gerard, 1999) and with a putative different ecological behaviour (the green form is usually linked to aquatic habitats) seem to be very similar in their ribosomal and mitochondrial sequences, forming a well-supported clade (100% and 81% BS for 16S and COI, respectively). However, recent breeding experiments (Lowe and Butt, 2008) have shown that some degree of reproductive isolation exists and they should be regarded as two different species. This has been partly confirmed in a recent phylogenetic study (King et al. 2008), which revealed the existence of exclusive COI haplotypes in each of these colour morphs. It should be noted here, however, that several subspecies have been assigned to this species based on differences in the position of the clitellum, sucker-like tubercula pubertatis, and in the number and position of spermathecae (Blakemore 2007, 2008) and therefore, further studies determining the variability of this species and the validity of its numerous synonymic names are required. The three remaining species belonging to the Aporrectodea and Allolobophora genera and investigated here (i.e. Ap. rosea (Savigny, 1826), A. oliveirae Rosa, 1894 and Ap. limicola (Michaelsen, 1890)) show undefined positions in both trees, suggesting that more detailed morphological and genetic information is needed. (ref. ID; 6916)
  1. Aporrectodea caliginosa (Savigny, 1826) (ref. ID; 6653, 6916) reported year? (ref. ID; 4494) reported author and year? (ref. ID; 76)
  2. Aporrectodea icterica (Savigny, 1826) (ref. ID; 5925, 6023)
  3. Aporrectodea limicola (Michaelsen, 1890) (ref. ID; 6023)
  4. Aporrectodea longa (Ude, 1885) (ref. ID; 6023) or 1895 (ref. ID; 6653) reported year? (ref. ID; 4494)
  5. Aporrectodea rosea (Savigny, 1826) (ref. ID; 6023) reported year? (ref. ID; 4494) reported author and year? (ref. ID; 76)
  6. Aporrectodea trapezoides (Duges, 1828) (ref. ID; 6023, 6916)
  7. Aporrectodea tuberculata (Eisen, 1874) (ref. ID; 6023, 6916)
  8. Aporrectodea turgida (Eisen, 1873) (ref. ID; 6023, 6916)

Aporrectodea caliginosa (Savigny, 1826) (ref. ID; 6653, 6916) reported year? (ref. ID; 4494) reported author and year? (ref. ID; 76)

Descriptions

Endogeic earthworm. (ref. ID; 76)

Aporrectodea icterica (Savigny, 1826) (ref. ID; 5925, 6023)

Descriptions

Color, white to greyish (formalin preservation). Live adults pinkish anteriorly, with clitellum bright yellow to orange-red, and post-clitellate region often yellow-orange owing to abundant mucus. Prostomium, closed epilobic. Setae, lumbricine, closely paired, all eight present on ii; ratio at xlix, 48:3:24:3:114. Dorsal pores begin at 4/5. Nephropores, minute, never identified with certainty except in xvi-xxxii, alternating irregularly from slightly above B to mD. Spermathecal pores, minute, three (rarely four) pairs in area of C, at 7/8, 8/9 to 10/11. Female pore, distinct though faint, in xiv, slightly dorsal to B. Male pore tumescences, xv, conspicuous, usually extending from just below A to mid-BC and often onto xiv or xvi. Male pores, minute, present in cleft of tumescence at median half of BC. Genital tumescences, pustules on individual A and B follicles, xxxii-xli (1), xxxii-xlii (3), xxxiii-xli (1), xxxiii-xlii (16), xxxiii-xlv (1), xxxiv-xlii (56); fused AB follicle pustules, x (10), xi (36), xii (8), xiii (43), xiv (21), xvi (16), xxix (7), xxx (6), xxxi(11), xxxii (24), xxxiii (13), xxxiv (1), xlii (3), xliii (77), xliv (75), xlv (22); fused CD follicle pustules, ix (77). Clitellum saddle shaped, xxxiii, xxxiv-xliii (rarely terminating on xlii). Tubercula pubertatis, bandlike, in clitellate specimens recognizable only as a colour variation of the clitellum, xxxiv-xli (1), xxxiv-xlii (5), xxxv-xlii (70), xxxvi-xlii (2). (ref. ID; 5925)
  • Internal Anatomy (n=20): Septa begin in 4/5, becoming increasingly muscularized until 9/10 or 10/11, then thin and membranous posteriorly. Hearts, five pairs, lateral in vii-xi. Holoic, nepharidia larger from xiii posteriorly than anteriorly. Califerous glands, one pair in x, vertical on each side of oesophagnus. Crop in xv-xvi. Gizzard in xvii-xix. Typhlosole beginning in xix-xxiii, reaching maximum size in segments lx-cxx, but terminating within 30 segments (mean 22) of anus. Seminal vesicles, four pairs, in ix-xii; pairs in xi and xii much larger than those in ix and x. Spermathecae, simple short duct, three (rarely four) pairs, in viii, ix-xi; occurrence in two specimens of unpaired spermathecae in xi. Ovaries, one pair in xiii, disclike, with four to nine ova in egg string. Ovisacs minute. (ref. ID; 5925)

    Remarks

    Similar variability in the positions of the spermathecae, the genital tumescences, the tubercula pubertatis, and the clitellum of the Guelph material have been noted in European collections of A. icterica by Gates (1969) and Bouche (1972). However, unlike Bouche's (1972) specimens, hearts in vi were never present, and the calciferous glands are restricted to x. Key external characters that should quickly and consistently separate mature specimens of A. icterica from other Canadian Lumbricidae are as follows: (1) clitellum originating behind xxxii and continuing for at least 10 segments; (2) genital tumescences in CD region of ix. Aporrectodea icterica is the 19th earthworm species to be recorded from Ontario and the 17th European earthworm species to become established in the province. (ref. ID; 5925)

    Measurements

    Length, all specimens strongly contracted, 46-91 mm (mean 65.07, SD 9.91); width at xlix 3-6 mm. Segments 123-184 (mean 157.32, SD 11.68). Secondary annulation may begin at vi or vii (n=78). (ref. ID; 5925)

    Aporrectodea rosea (Savigny, 1826) (ref. ID; 6023) reported year? (ref. ID; 4494) reported author and year? (ref. ID; 76)

    Descriptions

    Endogeic earthworm. (ref. ID; 76)