Notodasus dasybranchoides, Magalhães, Wagner F. & Bailey-Brock, Julie H., 2012

Magalhães, Wagner F. & Bailey-Brock, Julie H., 2012, Capitellidae Grube, 1862 (Annelida: Polychaeta) from the Hawaiian Islands with description of two new species, Zootaxa 3581, pp. 1-52 : 30-31

Notodasus dasybranchoides sp. nov.

Figures 20 C–F, 21 A–E, 22 A–D

Dasybranchus ? lumbricoides .— Hartman 1966: 228 –229. Bailey-Brock 1987: 387 –388.

Material examined. Holotype: Oahu Island: Kaneohe Bay, intertidal, 21°27ʹ55.61ʺ N, 157°49ʹ51.8ʺ W, 22 May 1980, coll. R. Brock ( USNM 1191159); Paratypes: same locality, date and collector as holotype (2, USNM 1191160; 2, BPBM R3609).

Additional non-type material: Coconut Island, little Beach, in sand with Arenicola brasiliensis Nonato , 0 4 Mar. 1983, coll. J.H. Bailey-Brock (fragments only); Hanauma Bay, 0 1 Jan. 1946, coll. R.W. Hiatt (4, BPBM R376); Maunalua Bay, Paiko Lagoon, intertidal, 21 Feb. 1973, coll. J.H. Bailey-Brock (1); Waikiki, 0 1 Jan. 1946, coll. R.W. Hiatt (2, BPBM R377); Barbers Point, 0 1 Aug. 1979 (1, BPBM R1977); Barbers Point Harbor, barge pier, 0 6 Aug. 1998, 12 m, coll. R.C. DeFelice (1, BPBM R2847); Honolulu Harbor, Pier 20, 12 m, 13 Nov. 1997, coll. R.C. DeFelice (1, BPBM R261); Honolulu Harbor, Pier 3–4 U.S. Coastal Guard Landing, 12 m, coll. R.C. DeFelice (1, BPBM R2643); Honolulu Harbor, Pier 5-6 HECO discharge, 13 Nov. 1997, 10 m, coll. R.C. DeFelice (1, BPBM R2649); Honolulu Harbor, Sand Island U.S. Coast Guard Station, 13 Nov. 1997, 12.5 m, coll. R.C. DeFelice (3, BPBM R 2655). Maui Island: Kahekili Beach Park collected on Halimeda kanaloana meadows, 30 m, Jun. 2005, coll. A. Fukunaga (1). Hawaii Island: Halape, 0 1 Jan. 1946, coll. R.W. Hiatt (1, BPBM R374; 1, BPBM R375).

Description. All specimens incomplete. Holotype about 130 mm long, 3 mm wide for 263 chaetigers. Largest paratype 10 mm long, 4 mm wide for 180 chaetigers. Body elongate, rounded dorsally, flattened ventrally, wider on mid-thoracic chaetigers, tapering posteriorly. Color in alcohol brownish–orange but a few specimens preserved as pale yellow.

Prostomium conical with short palpode withdrawn in all preserved specimens, with only anterior tip exposed ( Figs 20 C, 21A); nuchal organs and eyespots not observed. Proboscis papillated proximally and smooth distally. Peristomium achaetous, biannulated dorsally and slightly longer than anterior thoracic segments ( Figs 20 C, 21A).

Thorax with 12 segments, including one achaetous peristomium and 11 chaetigers ( Fig. 21 A). Thorax tessellated, more evident on anterior six segments, biannulate with deep intra-segmental grooves ( Fig. 21 A). First chaetiger biramous, thorax with short bilimbate capillaries only ( Fig. 21 A). Notopodia inserted dorso-laterally and neuropodia laterally. Lateral organs present throughout, between noto- and neuropodia but closer to notopodia ( Fig. 22 C). From chaetiger 12, lateral organs situated in deep pits above enlarged neuropodial lobe ( Fig. 21 A–C). Genital pores present throughout the abdomen.

Transition between thorax and abdomen marked by change in shape of segments only ( Figs 20 D, 21A, B); first two abdominal segments biannulate with capillaries, superior neuropodial lobe enlarged ( Figs 20 D, 21A, B); subsequent abdominal segments multiannulated with hooded hooks ( Figs 21 C, 22C). Abdominal noto- and neuropodia without well separated glandular tori pads ( Fig. 22 C). Notopodial glandular tori pads approaching each other on first 2–3 abdominal chaetigers, becoming further separated posteriorly ( Fig. 21 B). Neuropodial glandular tori pads lateral and ventral, leaving small ventral gap between ( Fig. 21 D). Notopodia with about 60 hooded hooks per fascicle, neuropodia with over 200 hooks; ventral-most notopodial hooks and dorsal-most neuropodial hooks usually with broken tips. Neuropodial lobes with hooks covering entire lobe anteriorly, leaving enlarged dorsal lobe ( Fig. 21 C); posteriorly, hooks covering only ventral half of neuropodial tori ( Figs 20 E, 21D, 22A). Noto- and neuropodial hooks similar; hoods short, not extending beyond main fang ( Fig. 22 D). Hooks with long anterior shaft, slight node and multiple teeth; in frontal view one main row of 4–5 teeth with a superior row of 3–4 small teeth ( Fig. 22 D).

Branchiae present after chaetiger 50 in a 250 chaetigers specimen; branchiae retractile with 10–12 branched tufts arising from midway between superior end of neurohooks and vesicular neuropodial lobe ( Figs 20 E, 21D, 22A–B). Pygidium simple with terminal anus ( Fig. 21 E).

Methyl green staining pattern. No distinct staining reaction. Body stains temporarily with a light green that fades away completely after a few minutes ( Fig. 20 F).

Distribution. Currently known only from Oahu, Maui and Hawaii in the Hawaiian Islands but several Eastern and Western Pacific records of D. lumbricoides may belong to this species.

Remarks. Live specimens are reported by Bailey-Brock (1987) as dark blue to purplish red. This species has been identified as Dasybranchus ? lumbricoides by Hartman (1966) and Bailey-Brock (1987); however, it does not belong to the genus Dasybranchus due to the presence of inflated abdominal neuropodial lobes as redefined in Green (2002). The current distinction between Dodecaseta and Notodasus is confusing and in need of revision; both having 13 chaetigers with capillaries only, 11 thoracic and two abdominal. They differ in the chaetal arrangement of the first abdominal segments; the first two abdominal chaetigers of Notodasus having only capillaries while Dodecaseta may have a different chaetal arrangement. The specimens from Oahu have no constriction between thorax and abdomen but have only capillary chaetae on the first two abdominal chaetigers placing them in the genus Notodasus .

Notodasus dasybranchoides sp. nov., differs from other species in the genus by the absence of a distinct MGSP, presence of a tessellated thorax, dorsally inflated neuropodial lobes and completely free abdominal notopodial lobes. The genus has been reviewed by García-Garza et al. (2009) and all species are illustrated therein according to their MGSP.

The species Dodecaseta eibyejacobseni Green (2002) shares some similarities with N. dasybranchoides sp. nov. and may actually belong to the genus Notodasus as pointed out by García-Garza et al. (2009). However, it differs from the new species described herein by the MGSP and dentition of the hooded hooks. Green (2002) analysed comparative material identified as Dasybranchus lumbricoides by Dr. O. Hartman collected from Mexico and concluded that these species were indeed distinct; however, she did not go further on the identity of this species which could actually belong to N. dasybranchoides sp. nov. Some of the Pacific specimens identified as D. lumbricoides in Fauchald (1972) and Hartman (1947) have been determined as Notodasus harrisae by García- Garza & León-González (2011) and D. lumbricoides may be restricted to the Philippines.

Etymology. The epithet of this new species refers to its frequent misplacement and similarity with species within the genus Dasybranchus Grube 1850 .

Figures

FIGURE 20. Mediomastus californiensis: A, MGSP of anterior end in dorso-lateral view; B, MGSP of posterior end with pygidium. Notodasus dasybranchoides sp. nov.: C, anterior end in frontal view showing prostomium, palpode and peristomium; D, transitional segments between thorax and abdomen; E, posterior abdominal segments in ventral view showing retractile branchiae; F, MGSP of incomplete specimen.

FIGURE 21. Notodasus dasybranchoides sp. nov.: A, anterior end in lateral view; B, transition between thoracic and abdominal segments in dorsal view; C, anterior abdominal segments in lateral view; D, posterior abdominal segments in ventral view showing tufts of branchiae; E, posterior end with pygidium.

FIGURE 22. SEM of Notodasus dasybranchoides sp. nov: A, posterior end in ventral view showing protruding branchiae; B, tufts of branchiae; C, posterior abdominal segments in lateral view showing lateral organs and branchial pores; D, abdominal hooded hooks.