Monticellina

Magalhães, Wagner F. & Bailey-Brock, Julie H., 2013, Bitentaculate Cirratulidae (Annelida: Polychaeta) from the northwestern Pacific Islands with description of nine new species, Zootaxa 3630 (1), pp. 80-116 : 99-101

Monticellina nr. cryptica Blake, 1996

Figure 14 A–F

Monticellina cryptica Blake, 1996b: 319 –321, fig. 8.22. Dean & Blake 2009: 113–114, fig. 5a–e.

Material examined. Mamala Bay, Barbers Point outfall, south shore of Oahu Island, Hawaii, Sta. HB4R3, 21°16ʹ47.2ʺ N, 158°01ʹ38.1ʺ W, 62.8 m, Sep. 2001 (1); Sta. HB2R4, 21°17ʹ0 0.6ʺ N, 158°01ʹ21.4ʺ W, 60 m, Sep. 2001 (1). Mamala Bay, Sand Island outfall, south shore of Oahu Island, Hawaii, Sta. E5R1, 21°16ʹ22.7ʺ N, 157°51ʹ40.9ʺ W, 101.5 m, Sep. 2008 (1 on stub, USNM 1195163). Guam, Mariana Island, Sta. 0 0 64, Jul. 2006 (2).

Description. Specimens 2.5–3.0 mm long, 0.1 mm wide for 38–42 chaetigers. Body elongate, with expanded thoracic region (8–10 chaetigers); dorsally rounded and ventrally flattened, without ventral or dorsal grooves. Color in alcohol white to pale yellow. Pygidium a rounded lobe ( Fig. 14 F).

Prostomium triangular, without eyes and nuchal organs present postero-laterally as vertical slits ( Fig. 14 A). Peristomium as long as 5–6 anterior chaetigers, with two distinct annulations, first annulation with two subannulations, second annulation with three sub-annulations ( Fig 14 A). Dorsal tentacles arising from posterior margin of the second peristomial annulation, together with first pair of branchiae, postero-lateral to dorsal tentacles ( Fig. 14 A). Second pair of branchiae on chaetiger 1 ( Fig 14 A); branchiae densely present on anterior and mid-body segments ( Fig 14 A), but scarce on posterior segments ( Fig. 14 F).

Parapodia from anterior segments with simple capillaries ( Fig. 14 B). Capillaries with sawtooth edge with widely spaced barbs numbering 2–3 per fascicle, present from chaetigers 18–20, accompanied by one simple capillary ( Fig. 14 C–E); barbs easily seen at 400×; last chaetigers without capillaries.

MGSP. The entire body with the exception of the prostomium and pygidium stain a smooth green.

Remarks. The specimens herein described agree partially with those originally described by Blake (1996b) but are closer to the description by Dean & Blake (2009) in which the peristomium is divided into two annulations and the dorsal groove throughout the body is not evident. The Hawaiian specimens were identified as Monticellina nr. cryptica due to the presence of the unique modified chaetae with widely spaced barbs easily seen under 400× magnification and the presence of the first pair of branchiae on the peristomium, behind the dorsal tentacles, an unusual character for Monticellina species (Dean & Blake 2009). However, the populations referred to as M. cryptica from Costa Rica and M. nr. cryptica Hawaii might actually be two undescribed and pseudocryptic species.

Biology/Ecology. Sampled from sandy bottoms adjacent to sewage outfalls at 60- 100 m.

Distribution. Mamala Bay, south shore of Oahu Island, Hawaii, USA. The record of this species for Oahu is new for the western Pacific Ocean.

Figures

FIGURE 14. SEM of Monticellina nr. cryptica. A, anterior end, dorso-lateral view; B, thoracic capillary chaetae; C, abdominal capillaries; D, abdominal capillaries showing the spaced barbs; E, detail of the barbed edge and fibrils; F, posterior end segments with pygidium.