The two species also show ecological differentiation: While the latter has papilliform
pharyngeal jaws and primarily feeds on algae, A.
2A, B) has the light-guiding distal appendage (DA) divided at the base; each main branch has a bifurcated tip and two tiny papilliform
side-branches; the base is surrounded by four escal lobes of about equal size, each with a slightly roundish tip; length of the DA is 24 mm (6.
Pronotum trapezoidal, widest at posterior margin, bearing widely dispersed hair-like sensilla on margins and shorter sensilla widely distributed distally, two small sternites each with two minute spines; meso- and metanota subequal in length; papilliform spiracle in pleural region of mesonotum near anterolateral margin of tergite.
Segments 1-7 with papilliform spiracle within sclerotized tergites, hair-like sensilla arising on posterolateral margins of abdominal segment 8 becoming progressively more anterior on segments 1-7; abdominal segments 7 and 8 (0.
1 A) with straight, wide, deep cervical groove and not reaching lateral margin; anterolateral margin with depression just posterior to anteroexternal orbital angle; lateral margin with approximately 12 papilliform teeth; postfrontal lobes small, oval and delimited anteriorly by 2 depression; median groove shallow; front lacking distinct upper border, frontal area sloping downward, bilobed in dorsal view, lower margin strongly sinuous in frontal view; upper and lower orbital margins each fringed with tubercles (Fig.
3 A) with straight, deep, narrow cervical groove ending some distance from lateral margin; anterolateral margin with shallow sinus just posterior to anteroexternal orbital angle, followed by a series of papillae until cervical groove, rest of anterior margin with papilliform teeth; posterior margin smooth; postfrontal lobes small, rounded and delimited anteriorly by 2 depression; median groove shallow; front with upper border sligthly demarcated by row of tubercles, bilobed in dorsal view, frontal area sloping downward, lower margin strongly sinuous in frontal view; orbital margins each with row of tubercles (Fig.
is characterized by having 15-16 thoracic chaetigers with four or five rows of uncini and up to three papilliform postchaetal processes on neuropodial lobes by the abdominal parapodia bearing flail-tipped neurochaetae, and by the presence on anterior-most abdominal chaetigers of interramal cirri and a low number of subpodial and stomach papillae.
1C-E) with a rounded postchaetal lobe bearing a papilliform process; last two thoracic chaetigers (Fig.
Mouth parts -- Mandible falcate and about twice as long as wide at base, weakly serrate on interior margin; maxilla with one hair-like sensillum on reduced cardo, stipes bearing two lateral hair-like sensillum on papilliform
projection between finger-like galea and origin of palp; maxillary palp with small sensillum near origin of 1st segment (x = 0.
6 mm) in diameter, with peripheral papilliform
ornamentation, pedunculated, concave; with 17 septa, two of them bifid, and other two incomplete; two central loculi of unequal size.