Gordionus bilaus n. sp.

(Figs. 3, 4)

Holotype. MSB: PARA: 111. Male collected from a tributary of the North Fork of Tesuque Creek (35.7699, -105. 7954).

Paratypes. Allotype. MSB: PARA: 112. Female collected from a tributary of the North Fork Tesuque Creek (35.7699, -105.7954). Other paratypes. MSB: PARA 113–120

Etymology. The species epithet is derived from the Navajo word for fingers, ‘bila’, which describes the shape of spines surrounding the cloaca (Fig. 3 C).

Distribution. Rocky Mountains, Santa Fe National Forest, New Mexico. Found at two sites. The first site (site 1), is also where G. lokaaus n. sp. was found, (35.7699, -105.7954), at an elevation between 3,200‒3,290m. The second site (site 3) consisted of an unnamed first order stream (35.7970, -105.8028), flowing just to the northwest of the Santa Fe Ski Area. This smaller stream merges with the Rio en Medio and the exact collection site was situated in a large grassy meadow surrounded by aspen/pine woodlands at an elevation of 3,230m.

Type locality. Site 1 (35.7699, -105.7954).

Bionomics. The worms were collected in the free-living, post-parasitic, adult stage, and the paratenic and definitive hosts remain unknown. Adults of this species were collected from late June through early August.

Material examined. Thirty four worms (26 males, 8 females) were extracted, amplified, and sequenced. The anterior, posterior, and midsection of eight individuals were used for SEM.

Description of male. Adult males brown in color, with the exception of one individual which was white, and measuređ 55‒I26 (x = 87•O) mm lοng• Areοles οf οne type, mοstly flat; ranging in shape frοm pοlygοnal (Fig• 3D) to round (Fig. 3 E and F). Interareolar furrows are not as distinct as G. lokaaus n. sp., and in many areas areoles appear fused with neighboring areoles (Fig. 3 D, E, and F). Tubercles between areoles present in moderate quantity (Fig. 3 F). Rows of small precloacal bristles present in posterior end, which are branched (Fig. 3 H). Cloacal opening surrounded by broad bristles (Fig. 3 C) with a stout apex; some bristles appear to be branching. Bristles around cloaca arranged into 2‒3 rows (Fig. 3 C). Postcloacal spines begin immediately posterior to the cloacal bristles and extend to the inner-side of the tail lobes (Fig. 3 A). The shape of the postcloacal spines is mound-like and tall with a diameter of 4‒8µm (Fig. 3 B). Adhesive warts are present anterior to cloacal opening (Fig. 3 G), canoe-shaped, and relatively wide (12‒22µm).

Description of female. Adult females white in color, with one exception which was brown, and measured 59‒2OO (x = 73•I) mm lοng• Cuticle resembles that οf the male (Fig• 4A anđ B)• Tubercles are slightly lοnger anđ more abundant in the anterior end (Fig. 4 C).

Diagnoses and taxonomic comments. Several morphological characters clearly separate these two new species. The spines/bristles surrounding the cloaca are dense and form a tube-like structure in G. l o k a a u s n. sp. (Fig. 1 C) but are finger-like and much narrower in G. bilaus n. sp. (Fig. 3 C). The areoles are clearly defined by interareolar furrows in G. l o k a a u s n. sp. (Fig. 2 A–C) but appear almost fused by the absence of interareolar furrows in G. bilaaus n. sp. (Figs. 4 A–C). Adhesive warts are thin, triangular and 2-dimensional in G. l o k a a u s n. sp. (Fig. 1 B) but tall, stout, mound-like, and 3-dimesional in G. b i l a u s n. sp. (Fig. 3 B). Finally, the adhesive warts of G. b i l a a u s n. sp. appear much broader (Fig. 3 G) than those of G. lokaaus n. sp. (Fig. 1 F).

Four Gordionus species have been described from the contiguous United States: G. l i n e a t u s (Leidy, 1851) from the eastern United States, G. longiareolatus (Montgomery, 1898) from California, G. platycephalus (Montgomery, 1898) from southern Montana (and also from Guatamala), and G. violaceus (Baird, 1853) from throughout the United States (and also found in Europe). In addition, Gordionus longistriatus Schmidt-Rhaesa, 2004 has been described from Hawaii (Schmidt-Rhaesa 2004) and Gordionus alascensis (Montgomery, 1907) has been described from Alaska.

The new forms described here are distinguished from all other Gordionus species by their unique combinations of cuticle and circumcloacal spine structures. The cuticle of G. l o k a a u s n. sp. resembles that of G. lineatus . However, in G. lineatus the circumcloacal spines are thin and long (Schmidt-Rhaesa et al. 2003; Smith 1991). The broad and tube-like circumcloacal spines of G. lokaaus n. sp. are unique within this genus and thus, distinguish this new species from G. lineatus . The cuticle of G. bilaus n. sp. resembles most closely that of G. violaceus, which has recently been shown to vary considerably throughout its European range (Schmidt-Rhaesa 2001b). However, the circumcloacal spines of G. violaceus are thin and long (Schmidt-Rhaesa 2001b) and resemble those of G. lineatus from the eastern United States (Schmidt-Rhaesa et al. 2003). The broad circumcloacal spines set G. bilaus n. sp. apart from all other previously described Gordionus species.

Laboratory rearing: Of almost 10 worm pairs of both species maintained in the laboratory for breeding purposes, mating was not observed and worm pairs never produced eggs. In addition, exhaustive searches in the field failed to find egg strings. Thus, measurements of eggs, larvae, and cysts could not be included in this manuscript.

Molecular analyses: Of the 88 worms sequenced, 30 unique nucleotide sequences were recovered. The phylogenetic tree based on the cox 1 barcoding region shows that the 2 new species produce 2 well-supported, monophyletic groups (Fig. 5). Sequences have been deposited in GenBank (JX244228 – JX244257).