Phyllognathopus inexspectatus Galassi & De Laurentiis 2011

FEMALE. Total body length, measured from tip of rostrum to posterior margin of caudal rami, 474 µm (holotype), 468 µm (paratypes mean value; n = 3). Body depigmented and eyeless. Habitus slender, no clear demarcation between prosome and urosome. Integument with surface pits, moderately sclerotized. Cephalosome subquadrate, with a dorsal rounded protuberance, hardly observable, referable to the dorsal integumental window (Fig. 10A). Couples of setule rows located on surface of cephalic shield. Rostrum elongate, subrectangular in shape, clearly articulated to the cephalosome; two dorsal sensilla laterally inserted on distal third, and one pore apically. Cephalosome and both thoracic and abdominal somites with cuticular ornamentation represented by reduced number of paired sensilla (Fig. 10A). First pedigerous somite free. Hyaline frills of cephalosome, somites bearing P1-P4 and urosome dorsally smooth. P5-bearing somite with large paired pores laterodorsally. Genital double-somite with three lateral spinule rows and three pairs of setule rows inserted dorsally. Female genital field located at the middle of genital double-somite. Genital apparatus simplified, copulatory pore located at half of the genital double-somite. Seminal receptacles laterally located and condensed close to the lamellar sixth legs. Urosomites with smooth hyaline frill ventrally, except third urosomite (Fig. 10B). Last two urosomites with spinular fringe on proximal third; anal somite with distal continuous spinule row. Anal somite with paired sensilla on dorsal surface (Fig. 11A), and two short spinule rows close to the anal operculum. Anal operculum rounded, protruding beyond insertion line of caudal rami and armed with strong spinules on free distal margin (Fig. 11A). Caudal rami rectangular with strongly expanded inner margin, slightly divergent, distinctly longer than wide (length/width ratio: about 1.5), with incomplete setal pattern (6 setae) (Figs 10C, 11A); anterolateral accessory seta (I) absent, anterolateral seta (II) smooth, inserted at proximal third of caudal ramus; posterolateral seta (III) inserted on distal third of ramus, transformed in a short and stout spiniform seta, with tuft of spinules apically. Outer terminal seta (IV) very short, thin, and naked, without articulation at base (Fig. 10C), distinctly shorter than caudal ramus; inner terminal seta (V) not transformed, very long, without articulation at base; terminal accessory seta (VI) as long as outer terminal seta, thin and naked; dorsal seta (VII) inserted at half of caudal ramus, about as long as caudal ramus or slightly shorter. A continuous spinule row along inner margin of caudal ramus and three spinule rows inserted close to the anterolateral seta (Figs 10B, 11A), at the basis of the posterolateral seta and at distal margin of ramus ventrally, respectively. Two pores are located dorsally on each caudal ramus, and one pore ventrally. Antennule (Fig. 11B): short, 8-segmented. Segment 1 with ventral spinule row. Both segments 1 and 2 bearing long and flaccid tube-pores. Armature formula: 1-[1], 2-[8], 3-[5], 4-[1 + (1 + ae)], 5-[1], 6-[3], 7-[4], 8-[6 +(1+ ae)]. Aesthetasc on segment 4 very large, reaching about the last antennulary segment. Antenna (Fig. 11C): coxa unarmed; basis with 1 transverse spinule row on surface; exopod 1-segmented, well-defined at base, with spinule row on surface, bearing 3 lateral unipinnate and 2 apical bipinnate setae; free endopod 2-segmented; both segments robust, of about the same length; segment 1 with inner spinule row; segment 2 with one inner and one surface spinule rows; armature consisting of 2 inner spines and 1 thin seta, 1 apical unipinnate spine, 4 geniculate setae, and 1 apical and 1 surface slender setae; two rows of spinules at outer corner and in subapical position on free distal margin, respectively. Mandible (Fig. 12A): coxal gnathobase elongate, cutting edge with 3 large and coarse teeth, 5 smaller fringed teeth; naked seta at dorsal corner. Mandibular palp biramous, basis with inner strong spinule row, exopod with 1 apical and 1 inner bipinnate setae; endopod with 1 inner bipinnate, and 1 spiniform and 2 bipinnate apical setae. Ornamentation as inFig. 12A. Maxillule (Fig. 12B): well developed arthrite incorporated into praecoxa, with 7 strong curved spines inserted on free distal margin, and 2 anterior surface setae. Proximal surface bipinnate seta inserted on tubercle absent (vs. present inPhyllognathopus viguieri, seeFig. 4D). Coxal epipodite represented by 2 setae; coxo-endite with 2 plumose setae. Exopod and endopod incorporated into basis, bearing 7 plumose setae. Maxilla (Fig. 12C): syncoxa with 3 endites. Proximal endite free, with 6 setae; medial and distal endites incorporated to syncoxa, each with 3 plumose setae, inserted as inFig. 12C. Allobasis drawn out into a strong claw apparently smooth, accompanied by 1 robust and 2 thin setae; endopod 3-segmented; segment 1 with 1 robust curved seta; segment 2 with 2 robust curved setae; segment 3 with 2 robust curved and 2 slender setae. Maxilliped (Fig. 12D): phyllopodial, lamelliform, 1-segmented, and slender than inPhyllognathopus viguieri. Trace of ancestral 2-segmented condition marked by the presence of outer incision, probably representing original segmentation boundary between segments 1 and 2. Armature consisting of 10 elements, of which 5 bipinnate setae in apical position, two of which with independent insertion, 1 unipinnate seta inserted along inner margin together with 4 strong unipinnate spines. No trace of incision along inner margin. P1-P3 with 3-segmented exopods and endopods. P4 with 2-segmented exopod and endopod. Intercoxal sclerites: boundary between intercoxa and basis not well defined at posterior surface in P2-P4. P1-P3 praecoxa well developed, with 1 outer spinule row. P4 praecoxa absent. P1 (Fig. 12E): praecoxa and coxa with outer spinule row on anterior surface. Basis with 1 outer spiniform seta and 1 inner spine; with spinule rows along outer margin, between exopod and endopod and at the insertion of inner spine, respectively. Exopod slightly longer than endopod: exp-1 and -2 with 1 outer unipinnate spine; exp-3 with 2 outer unipinnate spines and 2 setae, respectively inserted apically and subapically. Endopod: enp-1 unarmed, about as long as enp-2 and enp-3. Enp-2 cylindrical, with 1 inner short seta. Enp-3 with 1 inner bipinnate seta, 1 long unipinnate curved seta and 1 spiniform curved seta in apical position. Ornamentation as inFig. 12E. P2 (Fig. 13A): praecoxa and coxa as in P1; basis with 1 outer spiniform seta, with spinule rows along outer margin, and between exopod and endopod. Exopod distinctly longer than endopod; exopodal segments of about the same length; exp-1 and -2 with 1 outer bipinnate spine; exp-3 with 2 outer unipinnate spines, 1 apical unipinnate seta and 1 subapical long bipinnate seta. Endopod: enp-1 and-2 unarmed; enp-3 with 1 spine and 1 long bipinnate seta in apical position, 1 subapical short bipinnate seta. Ornamentation as inFig. 13A. P3 (Fig. 13B): ornamentation of praecoxa and coxa as in P1-P2. Basis with long outer seta and spinule rows along outer margin and at the insertion of the endopod. Exopod distinctly longer than endopod. Exp-1 and -2 with 1 outer bipinnate spine; exp-3 with 2 outer unipinnate spines, and 2 apical long bipinnate setae. Endopod: enp-1 and -2 unarmed; enp-3 with 1 unipinnate spine and 1 long bipinnate seta in apical position, 1 subapical bipinnate seta. Ornamentation as inFig. 13B. P4 (Fig. 13C): small sized, if compared to P1-P3; praecoxa absent, coxa and basis without ornamentation; basis with outer long and naked seta; exopod as long as endopod. Exp-1 with 1 outer long unipinnate spine; exp-2 with 1 outer long spine and2 apical setae. Endopod: enp-1 unarmed; enp-2 with 2 apical plumose setae. Ornamentation as inFig. 13C. P5 (Fig. 13D): free, with clear articulation to P5-bearing somite; right and left legs distinct; baseoendopod and exopod coalescent, incision marked original segmentation still present; basipodal outer seta present, exopodal armature consisting of 1 outer spine, 2 apical short setae, of about the same length, and 1 apical spine; baseoendopod armed with 2 robust bipinnate setae, the outer the longest. P6 (Fig. 13E): rudimentary, consisting of small paired chitinous lamellar plates not coalescent along medial margin, partially covering the genital field. Armature consisting of 1 long and slender bipinnate seta on each side. Male unknown.

Mazzoccolo karstic spring (Latium, central Italy)