Tanystylum occidentale
Creators: name: León-Espinosa, Angel De
name: León-Gonzalez, Jesus Angel De
name: Gómez-Gutiérrez, Jaime
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Pycnogonida
Pantopoda
Ammotheidae
Tanystylum
Tanystylum occidentale

description: Tanystylum occidentale (Cole, 1904)
(Figs. 8 A–G; 9 A–L)
Clotenia occidentalis Cole, 1904: 281–282, pl. 13, fig. 9, pl. 23, fig.4–8.
Tanystylum occidentalis Hedgpeth, 1954: 209; M̹ller, 1993: 85; Child & Hedgpeth, 2007: 660, Plate 330, fig. B; Murtaugh & Hernández, 2014: 412.
Material examined. 11 specimens: 1♀, (UANL-FCB-PYCNO-0063), Fiscal marine dock, La Paz, Baja California Sur, 24°09´41´´N, - 110°19´09´´W, 07/01/2013; 5♀, 4³, (UANL-FCB-PYCNO-0064), same sampling location, 06/26/2017; 1♀, (UANL-FCB-PYCNO-0065), FONATUR marine dock, Santa Rosalía, Baja California Sur, 27°20´13´´N, - 112°15´47´´W, 11/15/2013 (Fig. 1).
Description. Male: Trunk discoidal, glabrous, all segments completely fused, segmentation lines not observed. Lateral processes short, glabrous (Fig. 8 A; Fig. 9 E). Ocular tubercle subconical inserted in middle of cephalon, with two pairs of black eyes near base (Fig. 8 A–B; Fig. 9 D). Wide abdomen, inserted at the base of the third pair of lateral processes, with a 70° inclination, five distal setae and a pair of dorsal tubercles, and two pairs of dorsal setae (Fig. 8 A–B; Fig. 9 K–L). Proboscis cylindrical, short and thick, straight, directed forward, 1.4 times longer than wide. Triangular lips, each lip bordered by a band of long setae (Fig. 9 A–B).
Scape short, truncated, cone-shaped, with four to five distal setae, chela non-functional (Fig. 8 A–B; Fig. 9 B–C).
Palp with four articles, shorter than proboscis. First article short, glabrous. Second article longest, wide in the middle, attenuating towards the distal end, with an inclination toward the ventral side, with three long lateral setae, a dorso-distal and a short ventro-distal seta. Third article with a long lateral seta. Fourth article with a group of six setae, distal one longest (Fig. 8 C; Fig. 9 C).
Oviger with ten articles. Male oviger: First article short, with a mid-dorsal seta. Second article 1.8 times longer than the first article, with a proximal seta and two dorso-distal setae. Third article widened distally, with a dorso-distal seta. Fourth article with a dorsal-proximal seta. Fifth article longest, widened distally, with a long middle-dorsal seta. Sixth article with a middle-dorsal seta, a latero-distal seta, both short, and a long dorsal-distal seta. Seventh article with a mid-dorsal seta and two ventro-distal setae. Eighth article of equal size as the first one, with two ventro-distal setae. Ninth article with a postero-ventral seta. Tenth article short, with two long rigid setae directed forward (Fig. 8 F, 9 I–J).
Thick legs. First pair of legs longer than the others (Fig. 9 E). Coxa 1 small, with a ventro-distal seta and three mid-dorsal setae. Coxa 2 with ventral seta in the 3/4 and two mid-dorsal setae. Coxa 3 glabrous, small triangular gonopore present on antero-dorsal side (Fig. 9 E). Femur longest, widened distally, with two mid-dorsal setae and three dorso-distal setae; cement gland conical in shape located at the dorso-distal edge (Fig. 8 D, 9 G). Tibia 1, wider in the middle, with two mid-dorsal setae and two dorso-distal setae. Tibia 2 with four mid-ventral setae, and two at ventro-distal end, two mid-dorsal setae, and two pairs of lateral setae at the distal end. Tarsus with thick ventral setae, a small lateral seta, and two latero-distal setae. Propodus with a row of 13–14 spines covering the entire dorsal surface; heel with three thick spines and a small lateral seta, two small sole spines and three latero-distal setae near the base of the main claw. Main claw ½ the length of the propodus. Auxiliaries 2/3 the length of the main claw (Fig 8 D–E; Fig. 9 F, H).
Female: Tanystylum occidentale females have notoriously smaller ovigers than males, with the following morphology: First to fourth articles glabrous. Fifth article long, with a dorso-distal seta. Sixth article with two dorsodistal setae. Seventh article with long setae, one dorso-distal, two latero-distal and two mid-ventral. Eighth article with three long distal setae. Ninth article with one dorsal and one ventral seta. Tenth article very short, with two long terminal spines (Fig. 8 G).
Measurements of the male illustrated specimen (mm). Trunk: 0.73 long from the insertion of the chelifores until the insertion of the fourth pair of lateral processes, 0.61 wide between the second pair of lateral processes. Proboscis: 0.41 long, 0.22 wide (Fig. 8 A–B).
First leg: Coxa 1, 0.13; coxa 2, 0.18; coxa 3, 0.2; femur 0.63; tibia 1, 0.48; tibia 2, 0.6; tarsus, 0.06; propodus 0.35; main claw 0.18.
Third leg: Coxa 1, 0.11; coxa 2, 0.16; coxa 3, 0.13; femur 0.59; tibia 1, 0.39; tibia 2, 0.45; tarsus, 0.04; propodus 0.26; main claw 0.13.
Oviger: 1) 0.09; 2) 0.15; 3) 0.19; 4) 0.14; 5) 0.22; 6) 0.17; 7) 0.1; 8) 0.08; 9) 0.1; 10) 0.02.
Distribution. Cole (1904) described T. occidentale from Pacific Grove, California, USA. The specimens analyzed in the present work represent the first record of this species in Mexico, collected in Santa Rosalía and Bahía de La Paz, Baja California Sur. These records are about 2,300 km south from the closest previous record at Pacific Grove, California.
Remarks. Cole (1904) reported a single male specimen and the morphological characteristics are similar to the male specimens of the present study. Pacific Grove, California is the only previously known location of T. occidentale. The records of the present work extend its distribution range south (2,500 km) and to the east coast of Baja California Sur.
description: Published as part of León-Espinosa, Angel De, León-Gonzalez, Jesus Angel De & Gómez-Gutiérrez, Jaime, 2021, Pycnogonids from marine docks located along the west coast of the Gulf of California, Mexico, pp. 151-195 in Zootaxa 4938 (2) on pages 168-171, DOI: 10.11646/zootaxa.4938.2.1, http://zenodo.org/record/4563736