Description

Description of holotype. (♂) (Fig. 1). Counts and measurements: p = 102. a = 1. l = 398. (102 + 1 + T). BL = 18.93. HW = 0.31. HL = 0.39. ISW = 0.20. AW = 0.10. CW = 0.40. W 1 = 0.50. L 1 = 0.12. H 1 = 0.40. AS 1 = 0.43. A 7 W = 0.04. P 7 W = 0.03. Head pear-shaped, tapered anteriorly to round point at a 130 ° angle from antennal sockets; occiput gradually curved medially towards occipital foramen (Suppl. materials 1, 9: figs S 1, S 2, S 32, S 34). Head covered with long slender, erect setae (Fig. 2; Suppl. materials 1, 9: figs S 1 - S 3, S 32). Gnathochilarium and labrum closely appressed, tapered anteriorly to round point (Suppl. materials 1, 3, 9: figs S 1, S 3, S 10 - S 12, S 32). Labrum with anteromedial tooth-lined orifice (to, Fig. 4; Suppl. materialS 3,4: figs S 9, S 13, S 14). Labral surface without noticeable pores (Fig. 4). (However, the apparent lack of labral pores may be a result of specimen preparation for microscopy. Labral pores are present in I. plenipes and I. tobini. A few pores may be visible in Fig. 4 A). Shelf-like carina projecting dorsally from labrum-epistome margin (sh, Fig. 4; Suppl. material 4: figs S 13, S 15). Gnathochilarium and head capsule noticeably separate, with thin gap visible between (gp, Suppl. material 3: fig. S 10). Gnathochilarium thin plate-like, occupying nearly entire ventral surface of head (Suppl. material 3: fig. S 10). Gnathochilarium tightly appressed to ventral surface of head capsule, leaving a small gap anteriorly between labrum, gnathochilarial stipes. Gnathochilarium with sclerites: stipes (st), mentum (me), postmentum (pm), lamellae linguales (ll), cardines (cd) (cd, ll, me, pm, st, Suppl. material 3: fig. S 10). Gnathochilarial cardo (mistakenly homologized with the mandibular cardo in Marek et al. 2016) noticeable between head capsule, gnathochilarial stipes (cd, Suppl. material 3: fig. S 10). Stipes of gnathochilarium with inner, outer palps; outer, inner palps with 2, 3 setae, respectively (ip, op, Fig. 4; Suppl. materials 3, 4: figs S 10, S 13). Lamellae linguales with subapical palps (lp, Suppl. material 3: fig. S 10). Mandibles not externally visible (Fig. 4; Suppl. materials 1, 3: figs S 1, S 10). Mandible spear shaped, ca. 1 / 2 length of gnathochilarium (Fig. 4; Suppl. materials 3, 4: figs S 11, S 15). Mandible with pectinate lamella and four or five flabellate external teeth (md, et, pl, Suppl. material 4: figs S 13 - S 16). Molar plate absent. Mandibular pectinate lamella with numerous rows of jagged ventrally projecting serrulae, nested in groove of endochilarial frontal body (Fig. 4; Suppl. material 4: figs S 13 - S 16). Endochilarium with V-shaped frontal body. Endochilarium with fringed lobes (' spatulae' sensu Silvestri, 1903) that protrude distally through gnathochilarial stipes and lamellae linguales (fl, Fig. 4; Suppl. material 4: figs S 13, S 14). Antennae sub-geniculate, elbowed between antennomeres 3 and 4 (Figs 1, 2; Suppl. materials 1, 10, 11: figs S 1 - S 4; S 36, S 42). Antennae comprising eight antennomeres, 5 and 6 enlarged. Five sensillum types: four apical cones (AS) oriented in a trapezoidal cluster on eighth antennomere, with longitudinally grooved outer surface and circular pores apically (as, Fig. 2; Suppl. material 2: figs S 6 - S 8). Chaetiform sensilla (CS) widely spaced on antennomeres 1 - 7, each sensillum with one or two barbules (cs, Fig. 2; Suppl. materials 1, 2: figs S 1 - S 8). Trichoid sensilla (TS) oriented apically encircling antennomeres 6, 7, lacking barbules (ts, Fig. 2; Suppl. material 2: figs S 5, S 6). Small basiconic sensilla (Bs 2) in rows of six and seven oriented apical dorsally (retrolaterally) on antennomeres 5 and 6; smooth, capsule-shaped, 1 / 2 length of chaetiform sensillum (b 2, Fig. 2; Suppl. material 2: figs S 5, S 6). Spiniform basiconic sensilla (Bs 3) in row of 4, oriented apical dorsally on antennomere 7 (on longitudinal axis with Bs 2 on antennomeres 5, 6); sensilla tips facing apical cones; each sensillum with ca. 3 barbules encircling tip (b 3, Fig. 2; Suppl. material 2: figs S 6, S 7). Two auxiliary spiniform basiconic sensilla, each on distal rim of antennomere 7 oriented 120 ° from row of four (Suppl. material 2: fig. S 6). Antennae extend posteriorly to middle of tergite 3. Relative antennomere lengths 6> 2> 5> 3> 4> 1> 7> 8. Collum not concealing head, with straight anteromedial edge, gradually tapering laterally (Suppl. materials 1, 11: figs S 1, S 40 - S 42). Lateral margin of collum rounded, with thickened scaly carina (Suppl. materials 1, 3: figs S 4, S 10). This carina repeated serially on lateral tergal and pleural margins (absent from telson). Lateral tergal and pleural carinae jagged, saw-like (potentially interlocking), pronounced on midbody rings (Fig. 1, Suppl. material 5: fig. S 18). Metazonites slightly wider than prozonites, with faintly enlarged paranota (Suppl. materials 5, 11: figs S 17, S 39, S 40). Metazonites slightly arched (Suppl. material 9: fig. S 32). Metazonite dorsally covered with long, slender setae (Fig. 1; Suppl. material 11: figs S 40, S 41). Tergal setae hollow; tipped with translucent silk-like exudate, exudate sometimes tangled with neighboring setae (ex, Suppl. material 9: fig. S 35). Metazonite posterior margin (limbus) lined with anchor-shaped posteriorly projecting spines (an, Suppl. material 5: figs S 17, S 20). With row of conical spines anterior to limbus on ozoporiferous rings only (Suppl. material 5: figs S 17, S 20). Limbal anchor-shaped spikes alternating in size (large, small-sometimes large, small, small, large) along margin. Ozopores oriented dorsally, located near limbus (Suppl. material 5: fig. S 17). Ozopores absent from collum, tergites 2 - 4, telson. Ozopores elevated faintly on peritremata (porosteles absent), with two large backwards projecting spines, encircled with ca. 14 robust setae (sp, Suppl. material 5: fig. S 20). Row of stout flat tubercles along anterior margin of metazonite; tubercles absent medially. Posterior half of body with rings more convex (Suppl. material 10: fig. S 37), posterior-most tergites covered with a greater density of long, slender setae (Suppl. material 5: fig. S 18). Apodous ring without visible sternum, pleurites contiguous in midline. Apodous tergite densely setose, with unevenly distributed spikes localized to posterolateral corner; posterior margin lined with posteriorly oriented anchor-shaped spikes (Fig. 3 A; Suppl. material 6: fig. S 22). Telson covered with dorsally oriented stout spines on lateral surface only; without anchor-shaped spikes on margin (Suppl. material 6: fig. S 22). Prozonite highly sculptured, with 2 - 4 rows of discoidal flat tubercles (Suppl. material 5: fig. S 20). Tubercles in two shape classes: posterior prozonal tubercles button-shaped protuberant (tb); anterior tubercles flush (tf) with surface anteriorly (tb, tf, Suppl. material 5: fig. S 20). Pleurites quadrate, flat, with jagged scaly lateral, posterior, medial margins (Fig. 1). Pleurite medial margin broad, with scaly raised carina (Fig. 1). Pleurites plate-like, large, composing 4 / 5 of ventral ring area. Pleural medial margins overlapping lateral sternal margins, covering spiracles (Fig. 1). Sternites heart-shaped, wider anteriorly. Anterior, posterior sternites free, separate from pleurites (Suppl. material 5: fig. S 19). Sternum with prominent midline triangular ridge projecting ventrally, tapering to a point anteriorly (rd, Suppl. material 5: fig. S 19). Sternum with spiracles and legs oriented posteroventrally (Fig. 1; Suppl. material 5: fig. S 19). Spiracles circular, orifice open, hollow; oriented (above) dorsal to legs (Suppl. material 5: fig. S 19). Tergites, pleurites, sternites separated by arthrodial membrane (Suppl. materials 5, 6: figs S 18, S 19, S 22). Arthrodial membrane between tergites, pleurites wider posteriorly, pleated, thereby allowing telescoping body rings. Telson, paraprocts covered with long slender erect setae (Suppl. materials 5, 6: figs S 18, S 19, S 22). Setae on epiproct margin have inflated bases (potentially glandular in nature). Paraprocts quarter-spherical, anterior margins faintly scaly (Suppl. material 6: fig. S 22). Hypoproct small, ca. 1 / 8 area of paraproct, with four posterior projecting setae. Legs (postgonopodal) with seven podomeres (relative lengths denoted by numbers; 1 longest, 7 shortest): coxa (6), trochanter (7), prefemur (2), femur (3), postfemur (5), tibia (4), and tarsus (1). Legs with sparse setae, appearance similar to chaetiform sensilla with one or two barbules. Coxae nearly contiguous medially, separated by narrow sternal ridge. Coxa (postgonopodal legs) with large posteroventrally oriented D-shaped opening for eversible sac (Fig. 1; es, Suppl. material 5: fig. S 19). Eversible sacs membranous, distended slightly from aperture (Fig. 1). Tarsus with pincer-like claw, dorsal claw arcuate; ventral accessory claw thinner, arcuate, 1 / 2 length of dorsal claw (Suppl. materials 5, 6: figs S 18, S 22). Second leg pair with posteriorly oriented coxal gonapophyses; rounded, protuberant. Ninth, tenth leg pairs modified into gonopods, each comprising seven podomeres (Fig. 3; Suppl. materials 6, 7: figs S 23 - S 27). Anterior gonopod, ninth leg pair, robust, thicker than posterior gonopod, tenth leg pair (Fig. 3 A; Suppl. material 7: fig. S 25). Anterior gonopodal apex (podomere 7) spade-shaped; in repose cupped around flagelliform posterior gonopodal apex (podomere 7). Anterior gonopodal podomere 7 with four spines + 1 tarsungulum (Fig. 3 A; Suppl. materials 6, 7: figs S 23 - S 27). Anterior gonopodal podomere 3 with two setae. Posterior gonopodal podomere 7 deeply divided, comprising a bundle of five styliform articles, with one these articles (the tarsungulum) spike-shaped (i - v, Fig. 3 A; Suppl. material 7: figs S 25 - S 27). Four dorsal-most, longest articles laminate distally, recurving laterally, with denticulate posterior margins (i - iv, Fig. 3 B; Suppl. material 7: figs S 25 - S 27). Ventral-most, fifth article spike-like (v, Fig. 3 B). Accessory seta located proximal to fifth spike-like article at base of podomere (s, Fig. 3 B). Triangle-shaped sterna present between left and right gonopods of ninth and tenth leg pairs, thicker between posterior gonopods. Supplementary micrographs of I. socal sp. nov. are archived in the Dryad Data Repository at: https: // doi. org / 10.5061 / dryad. x 95 x 69 pq 7.

Common Names

Taxonomic Hierarchy

Kingdom: Animalia

Phylum: Arthropoda

Class: Diplopoda

Order: Siphonophorida

Family: Siphonorhinidae

Genus: Illacme

Species: Illacme socal Marek & Shear, 2023