Heterospio Ehlers, 1874

Blake, James A. & Maciolek, Nancy J., 2023, New species and records of Heterospio (Annelida, Longosomatidae) from continental shelf, slope and abyssal depths of the Atlantic Ocean, Pacific Ocean, Indian Ocean and adjacent seas, Zootaxa 5260 (1), pp. 1-74 : 6-7

Genus Heterospio Ehlers, 1874

Type species: Heterospio longissima Ehlers, 1874 , by monotypy.

Synonym: Longosoma Hartman, 1944 . Type species: Longosoma catalinensis Hartman, 1944 , by monotypy.

Generic Diagnosis. (emended): Body elongated, linear, divided into three regions: an anterior region with seven to nine short setigers, a median or abdominal region with greatly elongated segments, and a posterior bulbous region bearing three to five short segments. Prostomium narrow, conical, or broadly rounded to disk-like; nuchal organs narrow slits on posterior lateral margins. One pair of grooved peristomial dorsal tentacles, easily lost, arising from notches on dorsolateral surfaces of peristomium. Proboscis an eversible epithelial pouch. Anterior region with one to eight pairs of cirriform branchiae beginning on setiger 2, usually very long when present, arising above and near notopodia. Parapodia biramous with setal fascicles arising from near anterior margin of each segment. Anterior or thoracic region with simple capillaries in tightly defined fascicles, neuropodial acicular spines present or absent on setiger 1. Parapodia of abdominal segments with setae arranged in two elongate rows producing cinctures similar to those of some cirratulids. Abdominal setae include simple capillaries, acicular spines, aristate spines, and subuluncini. Posterior inflated section with acicular hooks.

Remarks. The number of branchial pairs, location of the first elongated segment, and the nature and arrangement of setae along the body are the characters most often used to separate species in the genus. However, there have been differing approaches to identify where the abdominal or elongated segments first begin, and other characters have proven to be equally important. See Discussion at end of paper.

The description of Heterospio longissima from off Ireland in 837 m by Ehlers (1874, 1875) was the first account of this unusual group of polychaetes. It was another 70 years before the second species, H. catalinensis ( Hartman, 1944) , (as Longosoma ) was described from southern California followed by H. sinica Wu & Chen, 1960 from China, H. mediterranea Laubier et al., 1974 and H. reducta Laubier et al., 1974 from the Mediterranean Sea, and H. peruana Borowski, 1994 from off Peru in abyssal depths. The two most recently described species are H. angolana Bochert & Zettler, 2009 from West Africa, and H. indica Parapar et al., 2016 from the Arabian Sea off India. Blake & Maciolek (2019) listed these eight valid species of Heterospio but noted that additional species from various deep-water collections were known to them.

In the present study, specimens have been accumulated from sites throughout the North Atlantic Ocean, Gulf of Mexico, off Brazil, California, SE Australia, New Zealand, the South China Sea, and the Indian Ocean. Most materials are from deep-water surveys. From these a total of 19 species have been identified, 15 new to science.

The following species of Heterospio , grouped by geographic area, are identified and treated in this study:

1. Heterospio hartmanae new species

2. Heterospio aruba new species

3. Heterospio bathyala new species

4. Heterospio canariensis new species

5. Heterospio dibranchiata new species

6. Heterospio guiana new species

7. Heterospio cf. reducta Laubier, Picard & Ramos, 1974

8. Heterospio southwardorum new species

9. Heterospio paulolanai new species

10. Heterospio alata new species

11. Heterospio bidentata new species

12. Heterospio brunei new species

13. Heterospio catalinensis ( Hartman, 1944)

14. Heterospio ehlersi new species

15. Heterospio knoxi new species

16. Heterospio peruana Borowski, 1994

17. Heterospio africana new species

18. Heterospio antonbruunae new species

19. Heterospio indica Parapar, Vijapure, Moreira & Sukumaran, 2016