Cognettia Nielsen & Christensen 1959
Creators: name: Martinsson, Svante
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Clitellata
Enchytraeida
Enchytraeidae
Cognettia

description: 3. Key to the species of Cognettia
1. 1-2 enlarged chaetae in lateral bundles of 2-3 segments within III-VII. ............................................... 2
- No enlarged chaetae. .................................................. 3
2. 2 enlarged chaetae per bundle, spermatheca with ectal gland and ampulla divided into two chambers (see Fig. 1D). ....................................... C. cognettii (Issel, 1905)
The enlarged chaetae are not mentioned as such in the original description, but the length range of chaetae given include them (see Schmelz & Collado 2010). The position of the enlarged chaetae are somewhat variable, they have been observed in III-V or IV-VI in material from the former Yugoslavia (Cernosvitov 1945), in V-VII in material from Britain (Cernosvitov 1945), in IV-VI or V-VII in material from Germany (Römbke 1989), and in V-VII in material from Scandinavia (pers. obs.). The species is distributed widely in Europe.
- 1 enlarged chaeta per bundle, spermatheca without ectal gland, and ampulla not divided into two chambers. ................. C. hayachinensis Nakamura, 2001
So far only found in Japan.
3. At least 3 chaetae in all bundles. .............................. 4
- All or some bundles with two chaetae. ......................10
4.Somebundleswith4chaetae................................................ ...... C. quadrosetosa Christensen and Dózsa-Farkas, 1999
An Arctic species, recorded from the Siberian tundra and N Greenland.
- 3 chaetae in all bundles. ............................................. 5
5. With well-developed secondary pharyngeal glands (see Fig 1A). .................................................................. 6
- Without secondary pharyngeal glands, but ventral lobes may be present (see Fig 1B). ................................ 9
6. Dorsal blood vessel arises in X, spermathecal duct without ectal swelling, but ectal gland well-developed (see Fig. 1D). ...................... C. lapponica Nurminen, 1965
An Artic species, recorded widely from the N Palaearctic region.
- Dorsal blood vessel arises in XIV, spermathecal duct with or without ectal swelling. ..................................... 7
7. Spermathecal duct without ectal swelling, ectal gland well developed. 3 pairs of pharyngeal glands, the two posteriormost with well-developed secondary glands, first pair of nephridia at 6/7, male pores in XII. ............................. C. zicsii Dózsa-Farkas, 1989
A South American species, known from the Ecuadorian Andes.
- Spermathecal duct with ectal swelling, ectal gland missing or rudimentary. ................................................ 8
8. Spermathecal duct with ectal swelling (see Fig. 1C), and a rudimentary ectal gland, spermatheca with ampulla divided into two chambers. Sperm funnel 2-3 times as long as wide. First nephridia at 6/7. ...... C. baekrokdamensis (Dózsa-Farkas, Felföldi, Nagy & Hong, 2018)
An E. Asian species, found in S Korea and Yunnan, China.
- Spermathecal duct with ectal swelling (see Fig. 1C), without ectal gland, spermatheca with ampulla not divided into two chambers. Sperm funnel 4-5 times as long as wide. First nephridia at 6/7. ....................................... C. floridae Healy, 1996
Only known from Florida, USA, this species is described to have 3 chaetae per bundles, in all body regions, occasional only two, therefore this species found in two places in the key.
9. First pair of nephridia at 4/5, four pairs of pharyngeal glands, male pores in X, spermathecal ectal gland absent. ............... C. paxi (Moszyńsk, 1938)
A doubtful species, the spermathecae indicate that it was possibly described from submature specimens. However, the position of the first pair of nephridia is unique for the genus, and if this is correct it is most likely a valid species. Described from C Europe.
- First pair of nephridia at 7/8-10/11, 3-5 pairs of pharyngeal glands, 0-2 with ventral lobes, dorsal blood vessel arises in X-XIV, male pores shifted forward to VIII-IX. ............................................... C. sphagnetorum (Vejdovský, 1878) / C. pseudosphagnetorum (Martinsson, Rota & Erséus, 2015b)
A cryptic species pair that can only be separated using molecular methods, both species found in Europe. Due to the recent split-up of the C. sphagnetorum complex it is in many cases impossible to know which species older records of ‘ C. sphagnetorum ’ refer to.
10. 2 chaetae per bundle in most or all bundles, both ventral and lateral. .....................................................................11
- 3 chaetae in a majority of the bundles, particularly postclitellarly. ................................................................12
11. Spermathecal ampulla not divided into two chambers, ectal duct with ectal gland present. Three pairs of pharyngeal glands, the two posteriormost with well-developed secondary glands, and the two anteriormost fused dorsally. .................................................. ........................................................ C. hibernica Healy, 1975
Found in Ireland, Portugal and NW Spain, possibly an Atlantic species.
- Spermathecal ampulla divided into two chambers, ectal gland absent. Three pairs of pharyngeal glands, the two posteriormost with well-developed secondary glands, and the two anteriormost fused dorsally. ........................... .............. C. bisetosa Christensen and Dózsa-Farkas, 1999
An Arctic species, recorded from the Siberian tundra.
12. Well-developed secondary pharyngeal glands in 2-4 pairs. ..............................................................................13
- Secondary glands absent, but ventral lobes may be present in 1-3 pairs. ............................................................ 16
13. 3 chaetae in all lateral bundles, 2 chaetae in some ventral bundles. ............................ C. ozensis (Torii, 2015)
So far only known from Japan.
- 2 chaetae in some lateral bundles, 2 or 3 chaetae in ventral bundles. .........................................................................15
14. First nephridia at 6/7, 3 pairs of pharyngeal glands, the two posteriormost with well-developed secondary glands, spermatheca with ampulla not divided into two chambers, ectal gland absent, duct with glandular swelling (Fig 1C). ................................. C. floridae Healy, 1996
Only known from Florida, USA, this species is described to have 3 chaetae per bundles, in all regions, occasional only two, therefore this species found in two places in the key.
- First nephridia at 7/8-11/12, 3-4 pairs of pharyngeal glands, 2-4 with secondary glands, spermatheca with ampulla divided into two chambers, ectal gland present (Fig 1D). ................................................................................ 15
15. 2 chaetae in all anterior (preclitellar) lateral bundles, 3 in other bundles, dorsal blood vessel arises in XVI-XX. Found in fully aquatic habitats. .................. .................................. C. glandulosa (Michaelsen, 1888)
Molecularly confirmed records from N and C Europe, but the species likely has a wider distribution, but many older records may refer to C. varisetosa.
- A mix of 2-3 chaetae in anterior (preclitellar) lateral bundles, sometimes 2 chaetae in all anterior lateral bundles and 3 in all other bundles, dorsal blood vessel arises in XIII-XVII. Found in semiaquatic and aquatic habitats. ............. C. varisetosa (Martinsson, Rota & Erséus, 2015a)
Holarctic, recorded from both Europe and Canada, many records of C. glandulosa may refer to this species. These two species overlap morphologically, and their identification may not always be possible using morphology alone.
16. Dorsal blood vessel arises in XV or more posterior. Often with 2 chaetae only in lateral bundles in II, and 3 chaetae in remaining bundles. ......................................17
- Dorsal blood vessel arises in IX-XIII. With several lateral anterior (preclitellar) bundles with 2 chaetae. .........................................................................19
17. A mix of 2 and 3 chaetae in lateral anterior (preclitellar) bundles, 5 pairs of pharyngeal glands, 2 pairs fused dorsally, dorsal blood vessel arises in XXII, male pores in X. .................... C. valeriae Dumnicka, 2010
So far only known from the Italian Alps, described from streams.
- 2 chaetae in lateral bundles in II, 3 chaetae in other bundles, 4-6 pairs of pharyngeal glands, 0-4 pairs fused dorsally, dorsal blood vessel arises in XV- XXIV, male pores in IX-XII. ...................................... 18.
18. 2-4 pairs of pharyngeal glands fused dorsally, dorsal blood vessel arises in XVII-XXIV, male pores in IX-XII. ............................................................................................ ........ C. chalupskyi (Martinsson, Rota & Erséus, 2015b)
Known from N and C Europe.
- 0-2 pairs of pharyngeal glands fused dorsally,dorsal blood vessel arises in XV-XVI, male pores in IX. ......................... ..................... C. asloae Martinsson, Klinth & Erséus, 2018
A Scandinavian species, found in Denmark, Norway, and Sweden, mainly aquatic.
Chamaedrilus alsoae is only known from a small number of specimens from Scandinavia, and it is possible that there will be even more morphological overlap with C. chalypskyi when more material is studied.
19. 3-5 pairs of pharyngeal glands, ventral lobes absent, chaetal formula 2.(3)-3:3-3, male pores in IX-XI, spermathecal ampulla divided into two chambers. .......... ................................................ C. chlorophila (Friend, 1913)
Widely distributed in Europe.
- 5 pairs of pharyngeal glands, 2 pairs with ventral lobes, chaetal formula 2,3-2,3:3-3, male pores in X, spermathecal ampulla with a single chamber. .................... ........................................... C. anomala (Černosvitov, 1928)
A doubtful species, the spermathecae indicate that it was possibly described from submature specimens, and it is possible that it is a synonym to C. chlorophila. Described from the Carpathians.
description: Published as part of Martinsson, Svante, 2019, A morphology-based identification key to the Cognettia species of the world (Clitellata: Enchytraeidae), pp. 37-43 in Soil Organisms 91 (2) on pages 40-41, DOI: 10.25674/SO91103, http://zenodo.org/record/10831555