Paralaophonte (Paralaophonte) ullama Gómez & Nazari 2021, sp. nov.

Paralaophonte (Paralaophonte) ullama sp. nov.

(Figs. 1–6)

urn:lsid:zoobank.org:act: 4B77A5F7-BAE9-4CB1-8333-87E9A4B7C818

Type material. ♀ holotype dissected and mounted onto seven slides (ICML-EMUCOP-180119-124).

Type locality. Mexico, Sinaloa State, Mazatlán, Urías coastal system, stn 1 (see also Gómez (2020a: 43, figure 1)); 23.15194°N, 106.3128°W; 1.5 m depth; organic carbon content 3.74%; organic matter content 6.43%; sand 25.31%; clay 35.75%; silt 38.94%; 18 Jan. 2019; S. Gómez leg.

Etymology. The specific epithet comes from the ancient Náhuatl name “ullama”, one of the few descendants of the pre-Columbian ballgame, ōllamaliztli (from the Aztec ancient Náhuatl ullama, ballgame, and ulli, rubber), played by the Aztecs and other Mesoamerican people. Ulama, considered one of the oldest team games, is at the verge of extinction and its three variants (stick ulama, forearm ulama, and hip ulama) are played only in few towns of Sinaloa state, north-western Mexico.

Differential diagnosis (based on the only female inspected). Laophontidae: Paralaophonte. Antennule sixsegmented; second segment with outer spiniform projection of moderate size. Mandibular palp with five setae (one basal, one exopodal, three endopodal). Maxilliped subchelate; syncoxa with two setae; endopodal claw slender, nearly as long as basis. P1 EXP three-segmented; P1 EXP3 with four elements. Armature formula of P2–P4 EXP/ ENP: P2 0,1,123/0,220; P3 0,1,223/0,321; P4 0,1,223/0,121. P5 EXP truncated, with six setae; P5 BENP with four setae. Caudal rami 1.5x as long as wide, with seven setae of which setae IV and V well-developed.

Description of the female. Total body length 435 µm measured from anterior tip of rostrum to posterior margin of caudal rami. Habitus (Fig. 1A, C) semi-cylindrical, without clear demarcation between prosome and urosome; covered with minute spinules dorsally and laterally.

Rostrum (Fig. 1A, C) small, fused to cephalothorax, bifid apically, with two sensilla.

Prosome (Fig. 1A, C) consisting of cephalothorax and three free pedigerous somites. Cephalothorax (Fig. 1A, C) reticulated, with sensilla and symmetrical depressions as shown; posterior margin with slender spinules, and with posterolateral extension. Posterodorsal and posterolateral margins of P2–P4-bearing somites with sensilla as depicted, with transverse row of small spinules and with longer elements as shown (Fig. 1A, C); P2-bearing somite without, P3- and P4-bearing somites with posterior medial pore dorsally (Fig. 1A).

Urosome (Figs. 1A, C, 2A, B) five-segmented. P5-bearing somite (Figs. 1A, C, 2A) ornamented with dorsal and lateral spinules as in previous somite, with posterolateral bulbous extension bearing a sensillum and furnished with spinules as depicted (Figs. 1C, 2A). Genital double-somite completely fused ventrally (Fig. 2B); original segmentation marked by dorsolateral spinular row indicating original posterior margin of proximal half of genital doublesomite (Figs 1A, C, 2A); both halves with dorsal and lateral spinules as in previous somite, with dorsomedial pore posteriorly, and with posterolateral bulbous extension (of anterior half without, of posterior half with sensillum) (Figs. 1A, C, 2A); ventral surface of both halves smooth, proximal half without, distal half with posterior slender spinules (Fig. 2B); P6 on proximal half of genital somite (anterior half of genital double-somite) (Fig. 2B). First free abdominal somite with dorsal and lateral spinules and mediodorsal pore as in distal half of genital double-somite, with fewer sensilla (Figs. 1A, C, 2A); ventral surface (Fig. 2B) covered with spinules as shown and with transverse row of posterior spinules. Second free abdominal somite as in previous somite, but without sensilla or posterolateral bulbous extension (Figs. 1C, 2A); ventrally largely as in previous somite (Fig. 2B).

Anal somite (Figs. 1A–D, 2A, B) with minute spinules scattered dorsally and laterally; with larger dorsolateral spinules close to insertion with caudal rami; anal operculum semi-circular, with small spinules along posterior margin and flanked by a sensillum and a longitudinal spinular row on each side; ventrally cleft medially, with two medial pores on each side and with posterior spinules close to insertion of caudal rami.

Caudal rami (Figs. 1A–D; 2A, B, D) cylindrical, slightly longer than wide, with straight outer and convex inner margin; dorsal and ventral surface covered with small spinules; medially with oblique spinular row; with transverse spinular row at the base of setae I, II and III, with additional dorsolateral spinular row close to insertion of seta IV and ventrally at the base of seta VI; with seven setae as follows (Figs. 1B, D, 2 D): setae I, II and III issuing laterally on distal fifth, seta I shortest, setae II and III subequal in length; distal setae IV and V with fracture plane, the former about one third the length of the latter and with distal half with outer spinules, seta V with distal half bipinnate; seta VI arising at inner distal corner; seta VII issuing dorsally near middle of each ramus, triarticulated.

Antennule (Fig. 3A) six-segmented; segments with spinules as shown; second segment largest, with outer spinous process. All setae smooth; armature formula: 1[1], 2[8], 3[7], 4[1+(1+ae)], 5[1], 6[9+acrothek]; acrothek of last segment consisting of two slender setae fused basally to slender aesthetasc.

Antenna (Fig. 3B) composed of coxa, allobasis, and free endopodal segment. Coxa small, ornamented with two rows of spinules. Allobasis with outer incision close to exopod marking original segmentation of basis and first endopodal segment; ornamented with few inner long spinules proximally; with median pinnate abexopodal seta. Exopod one-segmented; ornamented with outer spinules; with one lateral and three apical pinnate setae. Free endopodal segment as long as allobasis; with large spinules along inner margin, and outer subapical frill; laterally with one unipinnate and one smooth spine, and one slender seta; apical armature consisting of two smooth inner distal spines, two apical geniculate elements, and one geniculate outer distal seta fused basally to slender outer element.

Mandible (Fig. 4A) with well-developed coxa ornamented with short spinular row; gnathobase well-developed, with two blunt and three multicuspidate teeth, and one long pinnate seta. Mandibular palp one-segmented; exopod and endopod fused to basis; with five setae in all (one basal, three endopodal, one exopodal).

Maxillule (Fig. 4B) with praecoxal arthrite with few long spinules; with one lateral spine, and seven distal elements one of which a slender spine. Coxa small, with few outer spinules; coxal endite cylindrical, with few subdistal spinules and two setae one of which pinnate. Basis elongate, endite cylindrical and bearing one pinnate and two naked setae. Endopod fused to basis, with three subequal smooth setae. Exopod one-segmented, elongate, with two apical naked setae.

Maxilla (Fig. 4C) with syncoxa ornamented with small proximal inner spinules and longer outer subdistal ones; with three endites; proximal endite with few subdistal spinules and one seta, medial endite with one thick seta fused to endite and two slender elements, distal endite with three setae as shown. Allobasis drawn out into unipinnate claw, with slender spine, and one posterior and one anterior accompanying seta. Endopod small, one-segmented, with two bare setae.

Maxilliped (4D) with syncoxa ornamented with rows of spinules as shown, and with two pinnate setae. Basis unarmed, with few outer spinules medially. Endopod drawn out into long claw with slender accessory seta.

P1 (Fig. 5A) with elongate coxa ornamented with inner and outer spinules as depicted. Basis about 1.5x as long as broad, with spinular rows as shown; with bipinnate outer spine and inner pinnate spine, the latter situated medially at the base of inner pedestal. Exopod three-segmented; segments with outer spinules as shown; EXP1 with long outer spine ornamented with long spinules, EXP2 with smooth outer spine, EXP3 with two smooth outer spines and two distal geniculate setae. Endopod two-segmented, elongate; ENP1 2x as long as EXP, with slender inner spinules and comparatively stronger outer spinules; ENP2 with few inner distal spinules and armed with one strong claw and one small bare seta.

P2–P4 (Figs. 5B, 6A, B). Praecoxa triangular; with distal row of spinules. Coxa rectangular; with spinular rows as shown. Basis with outer spinules at base of outer element, the latter a pinnate spine in P2, but a bare slender seta in P3 and P4. Exopod three-segmented; EXP1 and EXP3 longest, EXP2 shortest; exopodal segments with outer spinules and surface pores as shown; EXP1 without, EXP2 with inner seta; P2 EXP3 with six (one inner seta, two apical elements, and three outer spines), P3 EXP3 with seven (two inner setae, two apical elements, and three outer spines of which distal most with coarser spinular ornamentation), P4 EXP3 with seven elements (two inner setae, two apical elements, and three outer spines with spinular ornamentation coarser than in P2 and P3). Endopods twosegmented, of P2 reaching slightly beyond EXP2, of P3 and P4 reaching slightly above and slightly below middle of EXP2, respectively; endopodal segments of P2 subequal in length, P3–P4 ENP1 shorter than second segment; segments ornamented with outer and inner spinules as shown; ENP1 without armature, P2 ENP2 with four (two inner, two apical), P3 ENP2 with six (three inner, two apical, one inner), P4 ENP2 with four elements (one outer, two apical, one outer).

P1-P4 setal formulae as follows:

P5 (Fig. 2A, C) with baseoendopod and exopod separated and ornamented with spinules as figured. Baseoendopod wide; with long slender spinules along inner margin; basal seta issuing from long setophore; endopodal lobe with three inner elements (two innermost elements spiniform and unipinnate, subdistal inner element a whip-like seta) and one distal seta. Exopod truncated, with six elements of which innermost bare.

Genital field and P6 (Fig.2B) smooth, located in proximal half of genital double-somite, with median copulatory pore. P6 symmetrical, with one bare seta.

Description of the male. Unknown.

Variability. The only female analyzed possesses two instead of one inner seta on the right P4 ENP2.