Pigrogromitus timsanus Calman 1927
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
Callipallenidae
Pigrogromitus
Pigrogromitus timsanus

description: Pigrogromitus timsanus Calman, 1927
(Figs. 10 A–F; 11 A–I)
Pigrogromitus timsanus Calman, 1927: 408–410, fig. 104 a–f; Hedgpeth, 1948: 214–216, fig. 23; Stock, 1975: 1015–1116; Child, 1979: 46; Staples, 1982: 457, fig. 2 G–J; Child, 1992: 59, 64, fig. 29. Clotenopsa prima Hilton, 1942d: 52–53, fig. 8.
Material examined. Two specimens: 2 ³, (UANL-FCB-PYCNO-0066), La Paz marina, Baja California Sur, 24°09´17´´N, - 117°19´31´´W, 26/06/2017 (Fig. 1).
Description. Body thick, trunk completely segmented, oval; distal end of the cephalon rounded (Fig. 10 A; Fig. 11 A, D). Each segment with a dorsal tubercle of the same height as ocular tubercle (Fig. 10 A). Lateral processes with two setae each, separated by less than ¼ of their own diameters (Fig. 10 A). Ocular tubercle conical, located mid-cephalon, with four eyes near the base and a pair of apical elongated structures (Fig. 11 C), and a similar tubercle on each of the following somites (Fig. 10 B, 11 D) (Fig. 10 A–B; 11 B, C). Abdomen three times longer than wide, directed backwards in a straight line, with four dorso-distal spines, the distal pair smaller (Fig. 10 A–B; Fig. 11 D, I). Proboscis cylindrical, thick, gradually widening towards the distal part, approximately 1.8 times longer than wide, directed forward (Fig. 10 A–B; Fig. 11 A). Triangular mouth, upper lip rounded, lateral lips triangle-shaped (Fig. 11 B).
Short chelifore, two-articled scape, ½ as long as proboscis. Chela with curved fingers (Fig. 10 A–B; Fig. 11 A–B).
Palps absent.
Oviger with 10 articles.Articles one to five glabrous. First article short. Second and third articles subequal, each two times longer than first one. Fourth and fifth articles longest, 3.5 and 4 times longer than the first article. Sixth article twice as long as the first, with five ventral setae in midline and two latero-distal setae. Seventh article 1.5 times longer than the first, with four dorsal and four ventral setae, plus two latero-distal spines. Eighth article of the same size as the first, with three ventral setae and two lateral setae. Ninth article ½ the size of the first one, with a ventro-distal seta. Tenth article smaller than ninth, with a thick mid-ventral seta. Oviger claw curved, slightly longer than ninth article (Fig. 10 E–F; Fig. 11 G–H).
Thick legs. Coxae 1–3 of similar length, 1 and 2 glabrous; coxa 3 with ventro-distal seta. Femur longest, as long as coxae 1 and 2 together, proximally wider, with two mid-ventral setae and a latero-distal seta. Tibia 1 with two dorsal bumps, single seta proximally and distally and two latero-distal setae. Tibia 2 as long as tibia 1, with two smaller dorsal bumps and a seta on each of them, two latero-distal setae, a middle-ventral seta and three ventro-distal setae. Tarsus armed with four ventral spines. Propodus with five ventral sole spines, a latero-distal seta, a mid-dorsal seta and two dorso-distal setae. Main claw ½ the length of the propodus, curved distally, no auxiliary claws (Fig. 10 C–D; Fig. 11 E–F).
Measurements of the illustrated specimen (mm). Trunk: 1.25 long from the insertion of the proboscis to the insertion of the abdomen, 0.91 wide between the second pair of lateral processes. Proboscis: 0.56 long, 0.32 wide. Third leg: Coxa 1, 0.17; coxa 2, 0.17; coxa 3, 0.17; femur 0.32; tibia 1, 0.26; tibia 2, 0.26; tarsus 0.06; propodus 0.31; claw 0.14.
Oviger: 1) 0.1; 2) 0.2; 3) 0.3; 4) 0.45; 5) 0.5; 6) 0.3; 7) 0.25; 8) 0.1; 9) 0.05; 10) 0.05.
Distribution. Pigrogromitus timsanus has a circum(sub)tropical distribution (Lucena & Christoffersen, 2019). Calman (1927) described P. timsanus from Lake Timsah, on the Nile Delta, Egypt; Hedgpeth (1948) expanded its range of distribution to the Gulf of Mexico, finding the species in Lake Worth, Florida, USA; Stock (1975) reports this species from Curaçao Island and comments that it has a circum-tropical distribution. Child (1979) reported specimens of P. timsanus from Baja California Sur, Mexico and both coasts of Panama. The most recent reports of this species are at Eastern Australia in the Pacific Ocean (Arango, 2003) and southern Atlantic (Lucena & Christoffersen, 2019).
Remarks. The current specimens from the Gulf of California differ from the holotype described by Calman (1927) in the absence of setae on the first two coxae. Propodus of the holotype presents three times more sole spines than the specimens of the present study. The oviger of the current specimens do not have setae on the first five articles, while the oviger of the holotype has four setae on the third article, one on the fourth and five on the fifth article. The rest of the oviger articles of the holotype of P. timsanus and the specimens from the Gulf of California do not differ in the number of setae. Another relevant morphological difference is the presence of four spines on the abdomen of the specimens from the Gulf of California; these are absent in the holotype (Calman 1927). Except for the setae of the abdomen, all these differences can be attributed to ontogenetic variability among specimens, because the two specimens observed from Baja California Sur were about 35% smaller than the holotype.
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 171-174, DOI: 10.11646/zootaxa.4938.2.1, http://zenodo.org/record/4563736