Hydroides diramphus Morch 1863
Creators: name: Sun, Yanan
name: Ten, Harry A.
name: Qiu, Jian-Wen
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Sabellida
Serpulidae
Hydroides
Hydroides diramphus

description: Hydroides diramphus Mörch, 1863
(Figure 2A, Figure 5 A–I)
Hydroides (Eucarphus) dirampha Mörch, 1863: 379.
Hydroides lunulifera — Day 1967: 807.
Hydroides dirampha —Huang and Mak 1982: 780; Mak 1982: 600, 602; Morton and Morton 1983: 278; Wang and Huang 1993: 1 –12.
Hydroides diramphus —Bastida-Zavala and ten Hove 2003: 83–86; Ben-Eliahu and ten Hove 2011: 17 –19.
Material examined. AM W40539, 10 specimens (22°25’N, 114°16’E, Tolo Harbour, on the submerged side of the floating Styrofoam boxes in the fish farm, 3–10 m, April 15, 2009); AM W41404, 3 specimens (22°17’N, 114°11’E, Victoria Harbour, on pier concrete columns, 0–1 m, May 20, 2009).
Description. TUBE: white, circular in cross-section; longitudinal ridges, if present, very low, collar-like rings absent. Transversal ridges present throughout the whole tube. External tube diameter from 1.4 mm to 2.6 mm (n=8, µ=1.9±0.4), lumen diameter from 1.1 mm to 2.0 mm (n=8, µ=1.5±0.3).
BRANCHIAE: radioles on each side arranged in semicircle, numbers ranging from 14 to 18 (n=8, µ=15.6±1.6). Interradiolar membrane absent. Terminal filament long.
PEDUNCLE: smooth, circular in cross-section, inserted below left branchial lobe in 12 specimens, right in 1 specimen. Constriction well-defined. Pseudoperculum club-shaped with an inflated tip, present in all specimens.
OPERCULUM: funnel radii with pointed tip, numbers ranging from 30 to 42 (n=8 µ=35.5±5.6). Interradial grooves almost 3/4 of funnel length. Verticil with 12 to 18 yellowish spines (n=8, µ=14.3±3.2), straight, all spines similar in size and shape. Tip of spines T-shaped and flattened (Figure 5 A), each having a basal internal spinule. External and lateral spinules absent. Central tooth absent. Length of operculum from 0.8 mm to 1.8 mm (n=8, µ=1.1±0.4), width from 1.1 mm to 1.8 mm (n=8, µ=1.3±0.3).
COLLAR AND THORACIC MEMBRANES: collar high, continuous with well-developed thoracic membranes.
THORAX: with 7 chaetigers, 6 uncinigerous. Collar chaetae of two types: bayonet chaetae with two long pointed teeth and smooth distal blade (Figure 5 B), and capillaries with minute denticles (Figure 5 C). Subsequent chaetae of two sizes (limbate and capillary, Figure 5 D). Uncini along entire thorax saw-shaped with 7 curved teeth including anterior fang (Figure 5 E). Tori of similar size throughout, approaching each other posteriorly, leaving a ventral depression.
ABDOMEN: total number of abdominal chaetigers varies from 64 to 103 (n=8, µ=85.3±12.9). Uncini sawshaped throughout with fang and 4 teeth anteriorly, increasing to 8 to 9 teeth (incl. fang) posteriorly (Figure 5 F–H). Chaetae flat trumpet-shaped (Figure 5 I). Capillaries present posteriorly, glandular pad absent.
SIZE: total worm length: 12.0 mm to 32.0 mm (n=8, µ =19.4±8.2), thoracic width: 1.2 mm to 2.0 mm (n=8, µ=1.6±0.5). Branchiae and operculum accounting for one fifth of entire length.
COLOUR: yellow to light brown.
Habitat. Depth: 1–10 m, on pier piles or other artificial substrate, fouling.
Distribution. Circum(sub)tropical.
Remarks. Hydroides diramphus has been reported as a fouling species, being ship-transported easily (Bastida- Zavala & ten Hove 2003) and present in both polluted and non polluted areas (Bastida-Zavala 2008). In Hong Kong, Hydroides diramphus occasionally occurs in the fouling community of local fish farms, co-occurring with Hydroides sanctaecrucis and Hydroides elegans on various submerged surfaces, with the latter species being dominant.
description: Published as part of Sun, Yanan, Ten, Harry A. & Qiu, Jian-Wen, 2012, Serpulidae (Annelida: Polychaeta) from Hong Kong, pp. 1-42 in Zootaxa 3424 on pages 7-11, DOI: 10.5281/zenodo.213363