Illacme Cook & Loomis, 1928

Marek, Paul E., Hall, Charity L., Lee, Cedric, Bailey, James, Berger, Matt C., Kasson, Matt T. & Shear, William, 2023, A new species of Illacme from southern California (Siphonophorida, Siphonorhinidae), ZooKeys 1167, pp. 265-291 : 265

Genus Illacme Cook & Loomis, 1928

Type species.

Illacme plenipes Cook & Loomis, 1928.

Species included.

Illacme plenipes Cook & Loomis, 1928; Illacme tobini Marek, Krejca & Shear, 2016; Illacme socal sp. nov.

Family placement.

The genus Illacme is placed in the family Siphonorhinidae based on the following morphological characters: Head pear-shaped (♂) or triangular (♀), not elongate nor with a beak, as in the Siphonophoridae (♂ Suppl. materials 1, 9: figs S1, S2, S32, S34; ♀ Fig. 1 ; Suppl. material 11: figs S36, S39). Antennae elbowed between antennomeres 3, 4 (Figs 1 , 2 ; Suppl. materials 1, 10, 11: figs S2-S4, S36, S41). Antennomere 1 set deep in cranium, not fully visible dorsally as in Siphonophoridae (Suppl. material 1: figs S2, S4). Antennomere 2 longer than wide, conical, not doughnut-shaped nor wider than long as typical in Siphonophoridae (Suppl. material 1: figs S1, S4). Anterior margin of collum straight, not medially emarginate as in Siphonophoridae . Sterna with prominent midline triangular ridge, projecting ventrally (Suppl. material 5: fig. S19). Posterior gonopods with distal podomere divided into 2-5 branches with one branch spike-like (i-v, Fig. 3B ; Suppl. material 7: figs S25-S27). See also diagnoses of Illacme in Shelley (1996b: 23), Marek et al. (2012: 85; 2016: 7), and Enghoff et al. (2015: 386); and of Siphonorhinidae in Shelley and Hoffman (2004: 218), Wesener (2014: 417), and Enghoff et al. (2015: 386).

Figures

Figure 1. Illacme socal sp. nov. A ♂ holotype, MPE 04621, and ♀ paratype, MPE 04622 (with head at top) B scanning electron micrograph of the head of ♀, MPE 04625 C micrograph of midbody rings of ♀, ventral view, MPE 04625. Scale bars: 1 mm (A); 0.5 mm (B, C).

Figure 2. Illacme socal sp. nov. Scanning electron micrographs A left, head and anterior rings of ♂ holotype, ventral view (MPE 04621) B right antenna of ♀ paratype, apical view (MPE 04976). Scale bars: 400 µm (A); 50 µm (B). Abbreviations: as, apical cones; b 2, small basiconic sensillum; b 3, spiniform basiconic sensillum; cs, chaetiform sensillum; ts, trichoid sensillum.

Figure 3. Illacme socal sp. nov. ♂ A anterior gonopod, left side, medial view B posterior gonopod, left side, medial view. Podomeres numbered. Scale bar: 50 µm (A, B). Abbreviations: i - v, styliform articles of the posterior gonopodal apex (podomere 7); s, accessory seta.