Helobdella echoensis, Saglam & Kutschera & Saunders & Saidel & Balombini & Shain, 2018

Saglam, Naim, Kutschera, Ulrich, Saunders, Ralph, Saidel, William M., Balombini, Katherine L. W. & Shain, Daniel H., 2018, Phylogenetic and morphological resolution of the Helobdella stagnalis species-complex (Annelida: Clitellata: Hirudinea), Zootaxa 4403 (1), pp. 61-86 : 71

Helobdella echoensis n. sp.

(York, PA)

( Figs. 2E – 7E )

(Holotype: ANSP GI 19496)

(LSID: urn:lsid:zoobank.org:act: F55674 B 6-1767-4 F64-ABEF-0347122944E0)

—Dorsal body light to yellowish-grey, sometimes with a greenish tint. Black dots on dorsal surface. Ventral coloration and annuli numbers same as H. serendipitious n. sp. One pair of eyes close to each other on segment III ( Fig. 7E ). Male and female gonopores in position similar to H. serendipitious n. sp. Six pairs of testisacs intersegmentally arranged from XII/XIII to XVII/ XVIII; shape similar to H. stagnalis but smaller. Ejaculatory bulbs (atrial cornua) moderately longer, ovoidcylindrical, lying at a much lower level by the sides of the atrium, connected by slender ejaculatory ducts with sharp turn backwards into atrium in XIth segment. Ovisacs large, connected with long and curled common oviduct. Oviduct length almost equal to ovisacs ( Figs. 2E , 4E ). Six pairs crop caeca, 6th directed backwards and short, extending up to fourth intestinal caecum. Four pairs intestinal caecum, first two pairs slightly curved upward, third pair flat and last pair curved downward. Rectum short, “S” shaped, similar H. stagnalis ( Figs. 3E , 5E ).

The dorsal nuchal scute of H. stagnalis from Europe has been depicted in a SEM-micrograph by Sawyer (1986, p. 538). Additional SEM identified differences in scute morphology and position between species ( Fig. 8 ). Specifically, the s cute of Helobdella spp. ranged from rhomboidal to hexagonal, settled on the12th and extending to the 13th annulus The H. modesta scute was square-shaped, settled on the 12th annulus (on the VII-a1) and sometimes extending up to half the 13th annulus ( Fig. 6B ). The H. serendipitious scute was pentagonal, settled in the dorsal surface of segment VII-a2 (on annulus 12) ( Fig. 6C ). The Helobdella eriensis n. sp. (Farm Pond) scute was similar to H. serendipitious n. sp. but settled in the 12th and up to all of 13th annulus ( Fig. 6D ). The Helobdella echoensis n. sp. (York, PA) was similar to H. serendipitious n. sp. but mushroom shaped ( Fig. 5E ).

Figures

FIGURE 2. Position of reproductive morphology of Helobdella species. A, Helobdella stagnalis; B, Helobdella modesta; C, Helobdella serendipitous n. sp.; D, Helobdella eriensis n. sp.; E, Helobdella echoensis n. sp. ac: atrial cornua; an, anus; e, eyes; fg, female gonopore; ic, intestinal caecum; mg, male gonopore; od, oviduct; os: ovisac; ps, posterior sucker; r, rectum; s, scute; sd, sperm duct; t, testisac, vd. vas deferens.

FIGURE 3. Position of digestive system of Helobdella species. A, Helobdella stagnalis; B, Helobdella modesta; C, Helobdella serendipitous n. sp.; D, Helobdella eriensis n. sp.; E, Helobdella echoensis n. sp. ac: atrial cornua; an, anus; cc, corp caecum; e, eyes; ic, intestinal caecum; p, proboscis;ps, posterior sucker; r, rectum; s, scute.

FIGURE 4. Dorsal view of reproductive system of Helobdella species. A, Helobdella stagnalis; B, Helobdella modesta; C, Helobdella serendipitous n. sp.; D, Helobdella eriensis n. sp.; E, Helobdella echoensis n. sp. a, atrium; ac: atrial cornua; os: ovisac; od, oviduct; sd, sperm duct; t, testisac, vd. vas deferens.

FIGURE 5. Digestive system of Helobdella species. A, Helobdella stagnalis; B, Helobdella modesta; C, Helobdella serendipitous n. sp.; D, Helobdella eriensis n. sp.; E, Helobdella echoensis n. sp. an, anus; cc, corp caecum; ic, intestinal caecum, r, rectum.

FIGURE 6. View of the scute (Nuchal plate) of Helobdella species. A, Helobdella stagnalis; B, Helobdella modesta; C, Helobdellaserendipitous n. sp.; D, Helobdellaeriensis n. sp.; E, Helobdella echoensisn. sp. s, scute; sb: scute base.

FIGURE 7. Eye position and shape of Helobdella species. A, Helobdella stagnalis; B, Helobdella modesta; C, Helobdella serendipitousn. sp.; D, Helobdella eriensis n. sp.; E, Helobdella echoensis n. sp.

FIGURE 8. Representative scanning electron micrographs of the chitonous plate (scute) of Helobdella stagnalis-like species. A, of Helobdella modesta. B, Helobdella serendipitous n.sp. C, Helobdella n. sp. (Montana).D, Helobdella n. sp. (Oregon).