Brevitalitrus hortulanus

Autor: Miyamoto, Hisashi, Morino, Hiroshi
Rok vydání: 2012
Předmět:
DOI: 10.5281/zenodo.4648903
Popis: Brevitalitrus hortulanus (Calman, 1912) (Figs 2–6) Talitrus hortulanus Calman, 1912: 133, figs 1–7; Barnard 1960: 16, fig. 1. Talitroides hortulanus: Stephensen 1943: 296, fig. 2. Brevitalitrus hortulanus: Bousfield 1971: 285, fig. 17. Brevitalitrus hortulanus var.: Bousfield 1971: 285. Brevitalitrus hortulanus var. (?): Bousfield 1971: 285. Material examined. Green Island, Taiwan, 22°40′N, 121°30′E, 7 August 1981, 3 females (4–8 mm), NSMT-Cr 21456; same data, 1 female (7 mm), NSMT-Cr 21457; same data, 5 females (5–7 mm), NMNS-6545-003. In Green Island, the present species was found under fallen leaves in the Guanyin-dong (ca. 54 m alt). Description of specimens from Taiwan. Female (7 mm, NSMT-Cr 21457). Eye (Fig. 2) weakly pigmented. Antenna 1 (Fig. 3A) long, peduncular article 3 1.3 times as long as article 2; flagellum 0.8 times as long as peduncle, 6-articulated. Antenna 2 (Fig. 3B) 0.5 times as long as body length; peduncular article 5 subequal in length to or slightly shorter than articles 3 and 4 combined; flagellum 1.4 times as long as peduncle, 17-articulated. Upper lip (Fig. 3C) deeper than wide, ventral margin pilose. Left mandible (Fig. 3D) with 4-dentate lacinia mobilis. Right mandible (Fig. 3E) with tricuspate lacinia mobilis. Lower lip (Fig. 3F) pilose along inner shoulders and margin of central cleft. Maxilla 1 (Fig. 3G, H) with outer plate dentition formula 0-0-3-4-4-3-3-3-3. Maxilla 2 (Fig. 3I, J) with outer plate bearing 6–8 blunt spines on edge (Fig. 3I, bl), 3–4 setulose sharp spines on dorsal side (Fig. 3I, st), and 7–8 brushy sharp spines on ventral side (Fig. 3J, br); inner plate with 7–8 blunt spines on oblique edge, 2–3 brushy sharp spines on ventral side, and 3–4 setulose sharp spines and 2 pappose spines on dorsal side (Fig. 3I, pp). Maxilliped (Fig. 3K, L) with inner plate bearing 3 teeth on distal margin, innermost tooth very small; outer plate with group of dense submarginal spines on ventral side (Fig. 3M) and distal pappose spine on dorsal side (Fig. 3N, pp); palp article 3 with many fine setae on inner margin, inner distal corner slightly produced, with a few spines, ventral surface with 2 long spines distally, and dorsal surface with 2–3 short spines distally; palp article 4 (Fig. 3O) partly fused to article 3, with 4–5 spines apically. Gnathopod 1 (Fig. 4A, B) with coxal plate bearing a few long spines on ventral margin; basis almost parallel-sided, with a few spines on posterior margin; carpus with a few long imbricated spines on lateral surface and posterior margin (Fig. 4B, im), posterodistal part of medial surface covered by tiny setae and with 3 long sheathed spines (Fig. 4B, sh); propodus shorter than carpus, with 5 bifid spines along posterior margin (Fig. 4B, bf), of which distal spine situated medially (Fig. 4C, bf), lateral surface with 3 long sheathed spines submarginally and 3 groups of 2 imbricated spines distally (Fig. 4B, im), medial surface with 3 short sheathed spines (Fig. 4B, sh); dactylus 0.5 times as long as propodus, with short imbricated spine near posterodistal angle of base. Gnathopod 2 (Fig. 4D) with coxal plate gently convex along ventral margin, posterior cusp strongly projecting; basis narrow, convex anteriorly, with several spines on anterior margin; ischium 0.5 times as long as basis; merus and carpus with blister-shaped swelling; propodus subequal in length to carpus; dactylus (Fig. 4E) hooked, with long imbricated spine on base of nail and short imbricated spine on grasping margin. Pereopods 3 and 4 each with coxal plate wider than deep; carpus 3.0 times as long as wide; propodus 1.3 times as long as carpus, distal spine lacking (Fig. 5I, J); dactylus 0.3 times as long as propodus. Pereopod 3 (Fig. 5A) with coxal plate posterior cusp hooked. Pereopod 4 (Fig. 5B) 0.9 times as long as pereopod 3; posterior cusp of coxal plate knob-shaped; dactylus (Fig. 5J) weakly notched. Pereopod 5 (Fig. 5C) 0.9 times as long as pereopod 3; anterior coxal lobe much broader (ca. 2.5 times) and slightly deeper (ca. 1.3 times) than posterior lobe, ventral margin gently curved; basis elliptic, posterior margin weakly serrated; propodus 1.2 times as long as carpus, with minute distal spine (Fig. 5K); dactylus 0.3 times as long as propodus. Pereopods 6 and 7 each with propodus subequal in length to basis, distal spine distinct on dactyl hinge (Fig. 5L, M); dactylus 0.3 times as long as propodus. Pereopod 6 (Fig. 5D) 1.4 times as long as pereopod 3; posterior lobe of coxal plate deeper than wide, ventral margin convex, serrated; basis long oval, posterior margin sparsely spinose, lacking posterodistal lobe; propodus 1.4 times as long as carpus. Pereopod 7 (Fig. 5E) 1.6 times as long as pereopod 3; basis ovate, posterior margin sparsely serrated, posterodistal lobe incised near junction with ischium; propodus 1.5 times as long as carpus, distal spine longer than that of pereopod 6 (Fig. 5M). Coxal gill of gnathopod 2 (Fig. 4D) large, leaf-shaped. Coxal gills of pereopods 3–5 (Fig. 5A–C) long and oval. Coxal gill of pereopod 6 (Fig. 5Q) convoluted, broadened distally, reaching distal margin of basis. Epimeral plates 1–3 each with straight posterior margin, posterodistal corner slightly produced. Epimeral plate 1 (Fig. 6F 1) with ventral margin slightly oblique. Anterodistal corner of epimeral plate 2 (Fig. 6F 2) rounded, ventral margin almost straight. Epimeral plate 3 (Fig. 6F 3) with gently curved ventral margin. Pleopods 1–3 each with 2 coupling hooks on peduncle (Fig. 6E); ramus shorter than peduncle. Pleopod 2 (Fig. 6B) slightly longer and wider than pleopod 1 (Fig. 6A); peduncle lacking marginal plumose setae; inner ramus longer than outer ramus, rami 3-articulated. Pleopod 3 (Fig. 6C, D) 0.6 times as long as pleopod 2; peduncle 1.4 times as wide as that of pleopod 2, outer margins pilose, with plumose seta on distal corner; inner ramus subequal in length to outer ramus, indistinctly articulated (Fig. 6D). Uropod 1 (Fig. 6G) with simple distolateral spine, 0.3 times as long as outer ramus; outer ramus with 2 marginal spines, inner ramus with 3 marginal spines. Uropod 2 (Fig. 6H) 0.5 times as long as uropod 1; outer ramus with marginal spine, inner ramus 1.3 times as long as outer ramus, with 2 marginal spines. Uropod 3 (Fig. 6I) shorter than telson; ramus 0.5 times as long as peduncle, with long spine and minute spine terminally (Fig. 6J). Telson (Fig. 6K) with medial suture-line on dorsal surface, each lobe with bifid spine terminally. Oostegites of gnathopod 2 (Fig. 4D) and pereopods 3–5 (Fig. 5N, O, P) each with 4–5 simple-tipped setae on distal margin. Remarks. Only females were available for examination. This species was originally described by Calman (1912) based on one male (8 mm) and one female (9.5 mm) from the "Tropical Pits" of Kew Gardens in London, U.K. Although the original location is unknown, there is little doubt that the occurrence of this species in London is due to an artificial introduction associated with soil or roots of plants. Since then, this species has been reported from the New Hebrides and Samoa (Stephensen 1943) and the Caroline Islands (Barnard 1960) in the tropical western Pacific region. Bousfield (1971) re-examined the type series of Talitrus hortulanus and the material of Stephensen (1943) and revealed that Stephensen's material from Samoa represented an undescribed species that Bousfield (1971) named B. stephenseni. The specimens from the New Hebrides and the Caroline Islands were referred to a variant of B. hortulanus because of the presence of subtle morphological differences from the type lot (Bousfield 1971). The present specimens from Taiwan agree with the descriptions and the figures of Calman (1912) and Bousfield (1971) except for the following points: (1) pereopods 6 and 7 each with propodus subequal in length to basis (vs propodus about 1.2 times longer than basis); (2) pleopod 2 lacking plumose setae on peduncle (vs with plumose seta); and (3) uropod 1 with 2 marginal spines on outer ramus and with 3 marginal spines on inner ramus (vs with 3 spines on outer ramus and 4 spines on inner ramus). These differences are subtle, and thus it is reasonable to consider that they could be within the range of intraspecific variation. Distribution. Peleliu Island, Palau, and Ton Island, Truk Islands (Barnard 1960); New Hebrides (Stephensen 1943); and Green Island, Taiwan (present study).
Published as part of Miyamoto, Hisashi & Morino, Hiroshi, 2012, Taxonomic Studies on the Talitridae (Crustacea: Amphipoda) of Taiwan. V. The Genus Brevitalitrus Bousfield, 1971, pp. 187-200 in Species Diversity 17 (2) on pages 188-193, DOI: 10.12782/sd.17.2.187, http://zenodo.org/record/4649310
{"references":["Calman, W. T. 1912. On a terrestrial amphipod from Kew Gardens (Talitrus hortulanus n. sp.). Annals and Magazine of Natural History 8: 392 - 398.","Barnard, J. 1960. Crustacea: Amphipoda (strand and terrestrial Talitridae). Institute Micronesia 4: 13 - 30.","Stephensen, K. H. 1943. The terrestrial amphipod Talitroides hortulanus (Calman, 1912) found in Samoa and in the New Hebrides. Entomologiske Meddelelser 23: 295 - 302.","Bousfield, E. L. 1971. Amphipoda of Bismarck Archipelago and adjacent Indo-Pacific islands (Crustacea). Steenstrupia 1: 255 - 293."]}
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