Haplotaxoides tehama Fend, 2024

Haplotaxoides tehama Fend View in CoL sp. nov.

( Fig. 4C–D, J–L View Figure 4 )

ZooBank LSID: urn:lsid:zoobank.org:act:37FA866E-433C-45C3-A409-DDFECAD66EAB

Holotype: USNM 1716314 About USNM : an immature worm, anterior end whole mounted, posterior end analysed for DNA (CE36030). COI DNA-barcode in GenBank (acc. no. PP988403 ); for other molecular data, see Table 1 View Table 1 . GoogleMaps

Type locality: USA, California, Tehama Co., Sacramento River at Tehama Bridge   GoogleMaps , in side channel on left bank. 40.0273º N, 122.1180º W, 9 Dec 2016; collected by S. Fend.

Paratypes: USNM 1716315–1716316 About USNM : from the type locality, 22 Oct 1996; one whole mounted, nearly mature worm (without DNA data); 9 Dec 2016; one whole mounted, mature worm (without DNA data) GoogleMaps . USNM 1716 About USNM 317–1716318: from the type locality, 9 Dec 2016; two immature worms, anterior ends on slides, posterior ends analysed for DNA ( CE36028 , CE36029 ); COI DNA-barcodes in GenBank (acc. nos PP988401, PP988457 ); GoogleMaps for other molecular data of CE36028, see Table 1 View Table 1 ; individual CE36029 was not used in our phylogenetic analyses.

Other material: S. Fend collection: USA, California, from the type locality, 22 Oct 1996; 10 whole mounts. 9 Nov 2016 ; two whole mounts. Shasta Co., Sacramento River at Redding , 21 Oct 1996; four whole mounts. All immature, all collected by S. Fend .

Etymology

Named tehama for the type locality, near Tehama, California. The word is of uncertain origin, but most likely a Nomlaki word for the location on the Sacramento River .

Description, nearly mature specimens

Length 41–42 mm, diameter in X 0.28–0.30 mm, maximum diameter 0.28–0.37 mm, 159–169 segments. Dorsal chaetae ( Fig. 4C View Figure 4 ) slightly sigmoid, simple-pointed, length 48–65 μm, diameter 3 μm with nodulus 0.43–0.49 the chaetal length from the tip. Ventral chaetae with a straight basal shaft and strongly arcuate distal part, tip with a small dorsal keel; length to 102–119 μm in middle and posterior segments, diameter 5–7 μm, nodulus 0.37–0.43 the length from the tip.

Head and musculature of mouth and anterior gut as described above, for Haplotaxoides decipiens (cf. Fig. 4I View Figure 4 ). Cuticular layer of body wall about 3 μm thick throughout. Prostomium anterior to transverse groove longer (190–200 μm) than wide (90–130 μm). Coelomocytes numerous throughout body, oval, 10–20 μm long, 7–10 μm wide. Midventral glands as described above for Haplotaxoides decipiens , usually 3 per cluster, to 150 μm long, 30–50 μm wide in mid-body. Nephridia as described above. Blood vessels obscure in available material.

Reproductive organs: testes in XII–XIII, sperm sac extending anteriad to IX or X, posteriorly through XIX; ovaries in XV.Large, transverse pores anterior to ventral chaetae in XIII; pores surrounded by a thick, glandular mass of columnar cells, about 120 μm wide ( Fig. 4K–L View Figure 4 ). Male funnels on 12/13 and 13/14, large and thick, each extending into anterior segment, but without sperm. Vasa deferentia simple, thin and inconspicuous; sinuous, apparently terminating in front of modified chaetae in XIII and XIV. Simple female funnels on 15/16 apparently extending into XVI. Spermathecae were not seen in either specimen.

In the mature 2016 specimen (paratype USNM 1716316 About USNM ), ventral chaetae in XIII – XIV strongly curved at base, remainder straight, with faint nodulus near basal 1/3; length about 175 μm, diameter about 6 μm, slightly widened at spear-shaped tip ( Fig. 4D, J View Figure 4 ). Midventral glands in XIII – XIV enlarged and highly granular ( Fig. 4J, K View Figure 4 ). Ovaries in XV only, simple female funnels to 70 μm high, on 15/16. One or two of the ventral glands in XVI greatly enlarged (to 350 × 220 μm) and highly granular ( Fig. 4J View Figure 4 ); corresponding chaetae enlarged and modified, to 185 μm long and 8–19 μm thick, straight and simple-pointed ( Fig. 4D View Figure 4 ).

The 1996 specimen (paratype USNM 1716315 About USNM ) ( Fig. 4L View Figure 4 ) had partially developed genital chaetae in XIII – XIV and in XVI, adjacent to normal somatic chaetae. Midventral glands in XIII and XIV were somewhat enlarged, and two glands in XVI were larger, extending up the sides of the segment.

Remarks

Although not sequenced, the specimens used to describe the sexual structures are considered paratypes, as all types are reasonably similar and were found in the same microhabitat. As noted above, Haplotaxoides tehama specimens are generally smaller than Haplotaxoides decipiens , and the cuticular layer of the integument is thinner. Spermathecae or dorsal glands (cf. Fig. 4F View Figure 4 ) were not seen in anterior segments. Other characters, such as morphology of chaetae, development of the pharynx, and distribution of coelomocytes were not noticeably different between the two taxa. Further morphological differentiation among species within this family may await collections of reproductively mature specimens.

Site description

The Sacramento River site is a large river with flow controlled by the upstream Shasta Reservoir. Although the region is subject to intensive agricultural land use, water temperature is generally between 10 and 20 °C, and many native fish populations are maintained ( Domagalski et al. 2000, May and Brown 2000). The sampled site is a riffle area in a side channel, with gravel to cobble-size substrate.