Helobdella blinni, Beresic-Perrins, Rebecca K., Govedich, Fredric R., Banister, Kelsey, Bonnie A. Bain,, Rose, Devin & Shuster, Stephen M., 2017

Beresic-Perrins, Rebecca K., Govedich, Fredric R., Banister, Kelsey, Bonnie A. Bain,, Rose, Devin & Shuster, Stephen M., 2017, Helobdellablinni sp. n. (Hirudinida, Glossiphoniidae) a new species inhabiting Montezuma Well, Arizona, USA, ZooKeys 661, pp. 137-155 : 140-144

Helobdella blinni sp. n. Figs 2, 3, 4

Type materials.

Holotype.USNM 1186106 (Table 2).

Additional materials.

Paratypes. (14 specimens) (USNM 1186107, 1186108, 1186109, 1186110, 1186111, 1186112, 1186113, 1186114, 1186115, 1186116, 1186117, 1186118, 1186119, 1186120) (Table 2)

Type locality.

USA, Arizona: Yavapai County, Montezuma Well (34.6491°N, 111.7522°W (DD)), aquatic system, under rocks, 10 June 2012, R.K. Beresic-Perrins.

Etymology.

We have named this new species, Helobdella blinni in honor of Dr. Dean W. Blinn for his dedication to natural history research at Montezuma Well. For over 20 years at Northern Arizona University, Dr. Blinn studied a wide range of organisms and their interactions at Montezuma Well including predator-prey interactions between Motobdella montezuma and the endemic amphipod, Hyalella montezuma Cole & Watkins, 1977.

Description.

External morphology. Length of specimens 11 to 22 mm (mean + SE 16.6 + 3.2 N=24) and width 3 to 8 mm (5.7 + 1.1 N=28) (Table 3, Figs 2, 3). Individual color ranges from translucent with brown spots to dark brown (Fig. 4). No dorsal papillae; one pair of eyes located at somite II (0.07 + 0.02 mm diameter, N = 11), distance between eyes 0.1 to 0.03 mm apart (N = 13). A scallop-shaped nuchal scute is present on the dorsal side, length 0.293 to 0.432 mm (0.335 + 0.05 N=9) and width 0.27 to 0.386 mm (0.32 + 0.04 N=9). One annulus separates the female and male gonopores. The caudal sucker diameter averages 1.6 + 0.3 mm (N = 27). The eggs (diameter 0.5 + 0.15 mm, N = 28) are laid on the ventral side of the parent in soft-walled transparent cocoons (7-11 eggs per cocoon, N = 7). The mouth is located subterminally in the oral sucker (Figs 2, 3).

Internal morphology. Average oral sucker diameter is 0.7 + 0.19 mm (N = 15), proboscis length is 3.5 + 1.1 mm (N = 17) (Table 3). Diffuse salivary glands are located near the anterior of the first pair of crop caecae. There are five pairs of smooth crop caecae and one lobed pair of posteriorly directed post caecae. Six pairs of compact testisacs are located in between each of the crop caecae. The intestine contains four pairs of caecae, with the first two pairs anteriorly directed and the other two pairs posteriorly directed. The intestine leads into an unraised anus located two annuli from the caudal sucker (Figure 3).

Development and growth. This species breeds year-round with peaks in spring and fall. Our specimens had an average of 7 to 11 white eggs (diameter 0.5 + 0.15 mm, N = 7) fixed to their ventral surface. Laboratory collections (2007-10) of Helobdella blinni documented the eggs hatching 1 to 2 weeks after ovipositing ( Beresic-Perrins 2010). Once hatched, the young attach to the ventral surface of the parent, allowing the parent to hunt for food and feed the young, occasionally feeding along with them. Prey consists of oligochaetes and other invertebrates. The average number of young per adult is 7 + 3.3 (N = 97) ranging from 1 to 14 offspring. The young remain attached to the parent for an additional four to five weeks after hatching. Once the juveniles leave the parent, they tend to aggregate together on rocks ( Beresic-Perrins 2010).