Capitella

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 : 16-19

Capitella sp.

Figures 6 C–D, 11 A–D, 12 A–F

Material examined. Oahu Island: Moanalua Stream, 21°21ʹ7.2ʺ N, 157°53ʹ45.6ʺ W, Environmental Monitoring and Assessment Program ( EMAP), state of Hawaii estuaries and bays, Oct. 2002, Sta. 16, (2, BPBM R3598; 9 on stub).

Comparative material examined. 2 males and two females of Capitella teleta Blake, Grassle & Eckelbarger, 2009 removed from laboratory cultures on Feb/2012, donated by Dr. E. Seaver (see notes in Blake et al. (2009) concerning stock’s origin).

Description. All specimens incomplete fragments; largest female (mature) 13 mm long, 0.6 mm wide for 32 chaetigers; largest male with 29 chaetigers. Body elongate, wider on mid-thoracic chaetigers, especially on chaetiger 5 of females, gradually narrowing on abdomen; body rounded dorsally and flattened ventrally with shallow ventral groove on thoracic chaetigers 5–9. Color in alcohol pale yellow.

Prostomium triangular, broad, longer than wide, shovel–shaped with dorsal depression extending through peristomium ( Figs 11 A–D, 12A–C); large nuchal organs postero-lateral to prostomium ( Fig. 12 B), eyespots not observed. Peristomium distinct from prostomium, wider in dorsal view and slightly shorter than chaetiger 1 ( Fig. 12 B). Proboscis not observed.

Thorax with nine segments; males and females with chaetigers 1–7 unilimbate capillaries only, 10–12 per fascicle. Segments of females increasing in width to chaetiger 5, tapering to end of thorax; chaetigers 8 and 9 slightly longer than other thoracic chaetigers, with 10–12 hooded hooks ( Figs 11 C–D, 12A). Thoracic segments 1–7 of males subequal, discretely wider on chaetigers 5 and 6, but chaetiger 5 not as distinct as in females ( Figs 11 A–D, 12C); chaetigers 8 and 9 highly modified, muscular, with notochaetae replaced by genital spines ( Figs 11 A, B, 12C, D); spines of chaetiger 8 directed posteriorly and those of chaetiger 9 directed anteriorly; chaetiger 8 with two sets of 3–4 short spines and chaetiger 9 with two robust spines ( Fig. 12 D).

Abdominal chaetae all hooded hooks; anteriorly with 10–12 hooks per fascicle, reducing posteriorly to 3–6 hooks. Abdominal segments multi-annulated at least 3x wider than anterior thoracic segments ( Fig. 12 A). Noto- and neuropodia with well separated glandular tori pads; posterior parapodial tori glandular. Hooded hooks similar on thorax and abdomen, with short hood extending slightly beyond main fang and crenulated margin ( Fig. 12 E, F). Hooks with moderate anterior shaft, slight node and multiple teeth. In frontal view with at least 3 rows of teeth, with three teeth in basal position, four in middle row and 4–5 in superior row ( Fig. 12 E, F). Posterior abdominal segments and pygidium not observed.

Methyl green staining pattern. Males without a distinct staining pattern, with a solid light green throughout ( Fig. 6 D) and females with chaetiger 4 darkly stained and chaetigers 7–8 intensely stained with lateral glandular patches ( Fig. 6 C; genital duct? see Blake 2009). Abdominal region uniformly light green; parapodial tori with sparse green speckles. Comparative material of C. teleta with chaetiger 6 in females darkly stained and a distinct band on anterior half of chaetiger 9 ( Fig. 6 E, F) as described in Blake et al. (2009).

Distribution. Specimens collected in Oahu, Hawaii.

Remarks. This Capitella species may belong to one of the sibling species identified by Grassle & Grassle (1976) but since a detailed description of the external morphology of these species is only available for Capitella teleta ( Capitella sp. I) and Capitella jonesi ( Capitella sp. III) it is impossible to identify to which species the Hawaiian material belongs. Blake et al. (2009) point out that these sibling species may be readily separated on the basis of prostomial shape, nature of the peristomium, shape of posterior end, distribution of hooded hooks, and several reproductive and developmental characteristics. We provide a full description of the Hawaiian material including photographs of the distinct MGSP of the females for future identification. The most similar sibling species is Capitella sp. IIIa, based on the shape of prostomium, peristomium and number of genital spines. The MGSP is unknown for these undescribed sibling species of Capitella , although Wu et al. (1991) illustrated it for Capitella sp. I and Capitella sp. II; however, as pointed out by Blake (2009), many more undescribed species of Capitella may exist and, as the Chinese material reported in Wu et al. (1991) could still be undescribed, delimitation of species using MGSP only would be unwise.

Biology. Tubes not observed. Mature females filled with eggs 40–50 µm in diameter.

Figures

FIGURE 6. Capitella jonesi: A, MGSP of anterior end in lateral view. Capitella minima: B, MGSP of anterior end in lateral view. Capitella sp.: C, MGSP of female individual; D, MGSP of male individual. Capitella teleta: E, MGSP of female individual; F, MGSP of male individual.

FIGURE 11. Capitella sp.: A, male individual in lateral view; B, male individual in dorsal view showing genital hooks; C, female individual in lateral view; D, female individual in dorsal view.

FIGURE 12. SEM of Capitella sp.: A, anterior end of female individual in lateral view; B, anterior end showing delimitations between prostomium, peristomium and chaetiger 1; C, anterior end of male individual in dorsal view showing genital spines; D, detail of male chaetigers 8 and 9; E, abdominal hooded hooks; F, top view of abdominal hooded hooks.