Limnodrilus paraclaparedianus Zhou & Cui, 2021

Zhou, Tingting, Peng, Yu, Wang, Hongzhu, Erséus, Christer & Cui, Yongde, 2021, Molecular taxonomy and description of a new species of Limnodrilus (Naididae, Clitellata, Annelida) in China, Zootaxa 5082 (4), pp. 301-321 : 313-316

publication ID	https://doi.org/ 10.11646/zootaxa.5082.4.1
publication LSID	lsid:zoobank.org:pub:1F7B3820-F248-4CA1-B630-4CD778B6792F
DOI	https://doi.org/10.5281/zenodo.5793889
persistent identifier	https://treatment.plazi.org/id/038F3041-CF74-FFAA-FF4F-FF64E947FC29
treatment provided by	Plazi
scientific name	Limnodrilus paraclaparedianus Zhou & Cui
status	sp. nov.

Treatment

Limnodrilus paraclaparedianus Zhou & Cui n. sp.

( Figures 4–6 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Limnodrilus “ claparedianus-cervix ”. Liu et al. 2017a: p. 483f., Fig. 3 View FIGURE 3 , Supplementary document S1, Suppl. Table S1 View TABLE 1 , Suppl. Fig. S2 View FIGURE 2 , S 3 View FIGURE 3 , S 5 View FIGURE 5 . Liu et al. 2017b: Table 1 View TABLE 1 , p. 251f.

Holotype. IHB HB20171202 About IHB a (CW0008), whole-mounted specimen, mature, stored at Institute of Hydrobiology, Chinese Academy of Sciences. Collected in the bottom sludge of Donghu Lake , Wuhan , Hubei (GPS: 114.352˚ E/30.535˚ N). COI barcode: GenBank MT 460105 View Materials .

Paratype. IHB HB20171202 About IHB b, whole-mounted specimen, mature, from type locality .

Other material. 1 specimen for SEM ( Fig. 4 View FIGURE 4 ), from type locality; IHB AH20171211 About IHB a–b (CW0009–CW0010), 2 mature specimens from Longganhu Lake, Anhui; IHB AH20171123 About IHB a (CW0011), 1 mature specimen from Huaihe River, Anhui; IHB JS20181130 About IHB a (CW0018), 1 mature specimen from Taihu Lake , Jiangsu. For more details see Table 1 View TABLE 1 .

Etymology. Named “ paraclaparedianus ” for the resemblance with “ Limnodrilus claparedianus Ratzel, 1868 ” in terms of the male genitalia.

Description. Length 18.00– 19.25 mm (fixed worms), first XII segments 2.85–3.30 mm (Holotype 2.85 mm), width at clitellum 0.42–0.54 mm (Holotype 0.42 mm), segments 80–95 (Holotype 80). Prostomium conical ( Fig. 4A View FIGURE 4 ). Clitellum inconspicuous.

All chaetae bifid ( Figs. 4C–F View FIGURE 4 , 5A–D View FIGURE 5 ). Anterior bundles with 4–7 chaetae, length 80–125 µm, width 2.5–3.7 µm, nodulus 1/3 from the distal end. 3–4 chaetae per bundle in mid-body, 1–2 per bundle in posterior segments. Upper tooth slightly longer than lower in anterior chaetae, thereafter progressively equal-to-shorter than lower towards the posterior part of body.

No modified spermathecal chaetae. Spermathecal pores ( Fig. 4B View FIGURE 4 ) paired ventrally in middle of X; male pores paired ventrally in middle of XI.

Chloragogen cells from VI. No coelomocytes. Male genitalia ( Fig. 6B View FIGURE 6 ) paired. Sperm funnel ( Fig. 6B View FIGURE 6 , sf) 90 µm long. Vas deferens ( Fig. 6B View FIGURE 6 , vd) long and coiled, 25–30 µm wide, entering atrium apically.Atrium ( Fig. 6B View FIGURE 6 , at) long, fusiform, 270–300 µm long, 75–80 µm wide. Prostate gland ( Fig. 6B View FIGURE 6 , pr) large, with irregular lobes, connected to middle of atrium. Ejaculatory duct ( Fig. 6B View FIGURE 6 , ed) leading to penis. Penis sheath ( Figs. 5E View FIGURE 5 , 6B View FIGURE 6 , ps) long, cylindrical, slender, narrowing from base to head, tapering abruptly with a constriction near the top; the latter bent with a teardrop-shaped plate placed in oblique position; sheath walls not abruptly reduced in thickness at constriction. Penis sheath 620–1030 µm long, 40–50 µm wide at base, 15 µm wide at top, 15–27 times longer than broad. Spermathecal duct ( Fig. 6A View FIGURE 6 , sd) 50–56 µm wide, ampulla ( Fig. 6A View FIGURE 6 , sa) difficult to observe but about 340 µm long, 215 µm wide in one specimen. Spermatozeugmata ( Fig. 6A View FIGURE 6 , sz) about 300 µm long, 35–60 µm wide.

Distribution and habitat: Species here reported from Provinces Hubei, Anhui, Jiangsu, Shanxi and Heilongjiang in China; also known (as “ L. claparedianus-cervix ”) from Europe ( Germany, Romania) and USA ( Liu et al. 2017a). Freshwater.

Remarks: This species has the character combination diagnostic of Limnodrilus ( Brinkhurst 1971; Liu et al. 2017a, b): no coelomocytes, bifid chaetae only, long vasa deferentia, small atria, large prostates connected to the middle of atria, long ejaculatory ducts, conspicuous cuticular penis sheaths, and presence of spermatozeugmata.

Elongate penis sheaths similar to the ones in L. paraclaparedianus are also present in L. maumeensis , L. cervix , L. claparedianus , and in a species of L. hoffmeisteri s.l. (species "III" in Liu et al. 2017a, Fig. 6 View FIGURE 6 ). Differences of these species to the new one are as follows: In L. maumeensis , the walls of the penis sheaths are conspicuously thickened on one side near the end, causing a bend in the shaft. In L. cervix , the walls of the penis sheaths are conspicuously thickened and abruptly thinner near the end, furthermore, the head has a triangular downward projection. In L. claparedianus , the upper tooth of the anterior chaetae is distinctly longer than the lower. Further subtle differences are the usually larger length/width ratio of the penis sheath (28 and more) and its rounded-triangular (vs. tear-dropshaped) head. In species III of L. hoffmeisteri , the upper tooth of anterior chaetae is much thicker and almost three times longer than the lower; furthermore, the head of the penis sheath is shaped like a plate-top, perpendicular to the long axis of the shaft (comp. Liu et al. 2017a, Fig. 3 View FIGURE 3 ).

The morphological and molecular characteristics of L. paraclaparedianus are identical with those of " L. claparedianus - cervix " described by Liu et al. (2017a), and therefore, we consider them as the same species. With the inclusion of the records in Liu et al. (2017a), it is clear that this new species is Holarctic in distribution.