POLYCIRRIDAE MALMGREN, 1866 EMEND.

Fitzhugh, Kirk, Nogueira, João Miguel De Matos, Carrerette, Orlemir & Hutchings, Pat, 2015, An assessment of the status of Polycirridae genera (Annelida: Terebelliformia) and evolutionary transformation series of characters within the family, Zoological Journal of the Linnean Society 174 (4), pp. 666-701 : 698-699

FAMILY POLYCIRRIDAE MALMGREN, 1866 EMEND.

Type genus. Polycirrus Grube, 1850 .

Definition

A phylogenetic hypothesis, unambiguously accounting for segment 2 being distinctly narrower than adjacent segments [character 19(1)]. Also offering explanatory accounts for the following characters (which can also be explained at the level of Terebelliformia , depending on transformation series; cf. Fig. 12 ): (1) expanded upper lip [cf. character 12(0)] rounded and midventral [character 13(1)]; (2) ventral surfaces of anterior segments [cf. character 21(1)] with discrete, paired glandular ventrolateral pads [character 22(0)]; and (c) mid-ventral groove [cf. character 24(1)] distributed from anterior segments 2–5 to pygidium [character 25(0)]. The presence of notopodia [cf. characters 29(0), 30(0), 30(2)] that are elongate [character 34(1)] is plesiomorphic for Polycirridae ; notopodia are, however, absent among members of Biremis [character 30(1)] and Hauchiella [character 29(1)].

Within a reproductively isolated population of individuals, the distinctly narrower segment 2 [character 19(1)] originated by unspecified mechanism(s) among individuals with the segment of the same width as adjacent segments [character 19(0)], subsequent to which character 19(1) became fixed in the population by an unspecified mechanism(s), and elongate notopodia [character 34(1)] originated by unspecified mechanism(s) among individuals with short notopodia [character 34(0)], subsequent to which character 34(1) became fixed in the population by unspecified mechanism(s) (with subsequent losses of notopodia among members of Hauchiella and Biremis blandi ). Additional tentative causal events (cf. Fig. 12 ) include: (1′) the expand- ed upper lip [cf. character 12(1)] being rounded and mid-ventral [character 13(1)], originated by unspecified mechanism(s) among individuals with an elongate, narrow upper lip [character 13(0)], subsequent to which character 13(1) became fixed in the population by unspecified mechanism(s); (2′) ventral surfaces of anterior segments [cf. character 21(1)] with discrete, paired glandular ventrolateral pads [character 22(0)], originated by unspecified mechanism(s) among individuals with a generalized glandular surface [character 21(1)], subsequent to which character 22(0) became fixed in the population by unspecified mechanism(s); and (3′) the mid-ventral groove [cf. character 24(1)] extending from posterior segments with notopodia to the pygidium [character 25(0)], originated by unspecified mechanism(s) among individuals with a groove extending from anterior segments to the pygidium [character 25(1)], subsequent to which character 25(0) became fixed in the population by unspecified mechanism(s). Following the character origin/fixation events in (1′)– (3′) were a series of population splitting events, leading to individuals to which lower-level systematics hypotheses refer (i.e. phylogenetic and specific).

Figures

Figure 12. One of the 54 minimum-length cladograms, showing transformation series for characters potentially relevant to defining Polycirridae. A–C and A′–C′ refer to respective alternative transformation series.