Lamyctes tristani
Creators: name: Popovici, George
name: Edgecombe, Gregory D.
name: Hall, Daniel W.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Chilopoda
Lithobiomorpha
Henicopidae
Lamyctes
Lamyctes tristani

description: Lamyctes tristani (Pocock, 1893)
(Figures 5, 6)
Material examined
2 adult ♀♀, NHMUK015626352, Diego Garcia, Downtown, 7.263°S, 72.374°E, 26 June 2022, leg. W. Rabitsch, suction sampler; 1 adult ♀, NHMUK015619670, Diego Garcia, wetland site, 7.310°S, 72.419°E, 22 June 2022, leg. W. Rabitsch, suction sampler.
Description
Body length up to 6.5 mm. Colour in ethanol: Cephalic shield and tergites uniformly dark brown, legs light brown with violet distal articles. No dark colouration around the ocellus and anterior margin of the cephalic shield.
Cephalic plate. Frontal margin with evident medial notch, lacking a median furrow, ocellus present (Figure 5 (A)). Posterior margin of cephalic shield weakly concave, with evident margination. Antennae of two specimens with 18–20 (Figure 5 (C)) and 21–24 articles respectively, 2.75 times longer than cephalic shield and 31% of body length. Ultimate antennal articles generally as long as or shorter than the penultimate (Figure 5 (B)). Pairs of articles 3–4, 6–7, 9–10, 12–13, 15–16, 18–19 relatively shortened.
Forcipular coxosternite. Subtrapezoidal with weak shoulder and gently converging lateral margin (Figure 6 (A,B)). Anterior margin with 2 + 2 teeth and a short, spinous pseudoporodont (Figures 5 (D), 6(C)). Pseudoporodont displaced proximally to teeth. Median diastema 1.7 times wider than the gap between teeth, narrowed medially. Long setae clustered near anterior margin and on the internal side of forcipular articles.
Trunk (Figure 5 (E)). All tergites with rounded posterior angles and without projections. Posterior margins weakly concave. Large tergites with complete posterior margination.
Legs. Distal spinous projection on leg pairs 1–12. Projection of tibia 12 short and rounded (Figure 5 (F)). Coxal pores on legs 12–15 arranged as 3, 3, 3, 4/3, 3, 4, 4 (NHMUK015626352). Middle two pores variably share an opening despite having separate channels. Telopodite of ultimate legs slender and elongate; tarsus 1 21% and tarsus 2 17% of its length (Figure 5 (G)).
Gonopods. Female gonopods with 2 + 2 spurs and simple claw (Figure 5 (H)). Article I with 13–14 setae, article II with 5–6 setae and article III with 1–2 setae. Male not known from Chagos samples (Figure 6 (F,G), for male gonopods of a syntype from Tristan da Cunha).
COI barcode. GenBank accession number PQ165824.
Remarks. Specimens from Diego Garcia compare closely with Lamyctes tristani, originally described from Tristan da Cunha (Pocock 1893; Lawrence 1956) and subsequently reported from Madagascar (Lawrence 1960). Among taxonomically informative similarities are the number of antennal articles (usually 23 or 24 in L. tristani), the blunt distal projection on the tibia of leg 12 (Figures 5 (F), 6(E)) and the female gonopods (Figures 5 (H), 6(H)), which all agree between the Chagos specimens and the type material of L. tristani. In both species, the distal spinous projection of the tibia is described as terminating on leg pair 11 (Figure 6 (D)).
description: Published as part of Popovici, George, Edgecombe, Gregory D. & Hall, Daniel W., 2024, New Chilopoda from the Chagos Archipelago, pp. 1885-1915 in Journal of Natural History 58 (41 - 44) on pages 1895-1896, DOI: 10.1080/00222933.2024.2395903, http://zenodo.org/record/14241441