Victoriopisa nhatrangensis Marin & Palatov 2022, sp. nov.
Creators: name: Marin, Ivan N.
name: Palatov, Dmitry M.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Eriopisidae
Victoriopisa
Victoriopisa nhatrangensis

description: Victoriopisa nhatrangensis sp. nov.
Figs 2–4, 12a
Material examined. Holotype, ♀ (bl. 8.5 mm), ZMMU Mb- 1217— VI ỆT NAM, Khánh Hòa province, Nha Trang Bay, Nha Trang City, the mouth of the Bé River, a little upstream from the bridge, 12°12’19.4”N 109°11’13.8”E, muddy bottom near the mangroves, 1 m depth, hand net and yabbi pump sampling, coll. I. Marin & S. Sinelnikov, May 2019.
Paratypes. 2♀♀ (bl. 7.8 and 8.0 mm), ZMMU Mb-1218—same locality and date as for holotype.
Additional material. 1♀ (LEMMI)—same locality and date as for holotype.
Etymology. The new species is named after the Nha Trang Bay and Nha Trang City, the famous locality for crustacean biodiversity studies, where it was discovered.
Description. Based on holotype female (ZMMU Mb-1217); only females are known.
Body (Fig. 2 a): body length 8.5 mm, with few small separate setae on dorsal surface of pereonites and urosomites, urosomites free (Fig. 7 f).
Head (Fig. 2 b): slightly wider than first pereonite, anteroventral margin entire, without anteroventral sinus; eyes present.
Antenna 1 (Fig. 3 a): about as long as body length; length ratio of peduncular articles 1–3 close to 1.0:1.1:0.3, with long separate setae distally, article 3 with 2 penicillate setae distodorsally; primary flagellum with 18 articles, each with distal setae, aesthetascs present on articles 7–17; accessory flagellum 2-articulated (Figs 3 b, 7 a), about as long as article 1 of primary flagellum, with 2 long distal simple setae.
Antenna 2 (Figs 3 c, 7 b): about 1/3 of the length of antenna 1; with ratio of lengths of peduncular articles 3–5 close to 1:1.9:2.1; flagellum short, consists of 2 fused long articles and 3 short articles, reaching 0.68 times as long as peduncular article 5, with groups of small setae.
Upper lip (Fig. 4 a): oval, bearing fine setae dorsally.
Lower lip (Fig. 4 b): inner lobes well-developed, with fine setae; outer lobes with small dense apical setae.
Mandible (Fig. 4 c–f): left incisor (Fig. 4 c) with 5 teeth; lacinia mobilis with 4 teeth; accessory setal row consisting of 6 serrated setae and several fine setae (Fig. 4 d); molar columnar; palp with 3 articles in length ratio of 1.0:2.7:2.8, article 3 equal to article 2, armed with 4 long simple D-setae and 9 long distal E-setae, article 2 with 3 setae along medial margin (Fig. 4 c). Right mandible (Fig. 4 e): incisor and lacinia mobilis with 3 teeth; accessory setal row composed of 6 serrated setae (Fig. 4 f); molar with longer seta; general proportions similar to left mandible.
Maxilla 1 (Fig. 4 g): inner plate with 12 plumose setae and 2 simple setae; outer plate with 9 serrated apical spines (Fig. 4 h); palp 2-articulated, article 2 with 4 stout spines distinctly, 6–7 stiff setae, 1 large distal and 1 subdistal setae.
Maxilla 2 (Fig. 4 i): inner plate with 12 plumose setae in an oblique row and simple setae on apical margin; outer plate with 8 slender simple setae and a few (15–16) fine setae on apical margin.
Maxilliped (Fig. 4 j): inner plate with 4 stout apical spines, 12 plumose setae, 4 robust setae on apical margin; outer plate about twice longer than inner plate, with a number of simple setae on apical and lateral margin; palp 4- articulated, article 2 with convex inner margin covered with numerous simple setae, article 3 subovate, with several groups of facial setae, article 4 rather claw-like with 1 seta on outer margin and 3 small setae on inner margin.
Coxal gills: present on gnathopod 2 and pereopods 3–6; gills of gnathopod 2 (Fig. 3 f) and pereopods 3–4 much longer than basis of corresponding pereopods (Fig. 5 a, c), gill 5 slightly longer to basis of pereopod 5 (Fig. 5 d), gill 6 much shorter than basis of pereopod 6 (Fig. 5 f).
Oostegite (Figs 3 f, 5 a, c, d): present on gnathopod 2 and pereopods 3–5, slender, longer than width, with numerous long simple setae on margins.
Gnathopod 1 (Figs 3 d, 7 d): subchelate, significantly smaller than gnathopods 2: coxal plate subrectangular with oblique ventral margin, posteroventral corner notch absent; basis expanding distally, about 3 times as long as distal width, with 4 groups of paired setae and 1 simple seta on posterior margin, several short and long simple setae on posterodistal corner; ischium as long as wide, smooth; merus slightly longer than wide, setose facially, with 4 large subdistal setae; carpus about 2.5 times as long as wide, with 5 double-rows of long simple setae along posterior margin; propodus (palm) dilated distally, with 5 spines on posterodistal corner, 3 simple setae along medial side, and 6 short spines along palmar margin; dactylus curved, robust, with 1 simple seta on posterior margin.
Gnathopod 2 (Fig. 3 f, g): subchelate; coxal plate ovoid, wider than length, with 3 small thin setae on anterodistal corner, with straight ventral margin, posteroventral corner notch absent; basis longer than ischium, merus and carpus, expanding distally, about 2.9 times as long as distal width, with straight median lateral margins, with 5 simple setae on posterior margin and 4 long simple setae on posterodistal corner; ischium as long as wide, smooth; merus subquadrate slightly longer than wide, posterior median surface slightly convex and smooth; carpus triangular, lobed, about as long as wide, with 4 rows of long simple setae along posterior margin; propodus (palm) (Figs 3 g, 7 e) elongated, teardrop-shaped, about 1.7 times as long as maximal width, anterodistal corner convex, slightly setose; palmar margin composed of 1 lobe, 2 excavations and 2 large medial robust setae, lobe with small lateral robust spine-like setae (Fig. 12 a); dactylus stout, strongly curved, ventral margin with deep median excavation and proximal lobe (protrusion), with straight sharp tip.
Pereopod 3 (Fig. 5 a, b): slender; coxal plate rectangular, about twice wider than length; basis linear, with straight median margins, about 3.4 times as distal width, with smooth anterior margin, 11 long setae on posterior margin and 2 long accompanied by 2 short simple setae on posterodistal corner; ischium as long as wide, smooth; merus about 2.2 times as long as maximal width, with anterior margin protruding forward, armed with 2 anterodistal setae, with 3 setae on distal part of posterior margin; carpus elongated, about 3.2 times as long as wide, with 3 simple setae on anterior margin and 9 separate and grouped long setae on posterior margin; propodus about 5.3 times as long as wide, linear with straight margins, with 3 long simple setae on anterior margin, with 3 small spines accompanied by groups of setae along posterior margin and 1 spine on posterodistal corner; dactylus (Fig. 5 b) long, slender and curved, about 7 times as long as width, with penicillate seta on anteroproximal margin and 1 fine seta subdistally.
Pereopod 4 (Fig. 5 c) almost similar to pereopod 3: coxal plate rectangular, about twice wider than length; basis linear, with straight median margins, about 3.3 times as distal width, with smooth anterior margin, 8 long setae on posterior margin and 2 long simple setae on posterodistal corner; ischium as long as wide, with 1 long seta on posterodistal corner; merus about 2.1 times as long as maximal width, with anterior margin protruding forward, armed with 1–2 anterodistal setae, with 2 double setae on posterior margin; carpus elongated, about 2.8 times as long as wide, with 1 seta anterior margin and 2 setae on anterodistal corner, with 4 double setae on posterior margin; propodus about 5.7 times as long as wide, linear with straight margins, with 3 long setae on anterior margin, with 4 small spines accompanied by groups of setae along posterior margin and 1 spine on posterodistal corner; dactylus long, slender and curved, about 6 times as long as width, with penicillate seta on anteroproximal margin and 1 fine seta subdistally.
Pereopod 5 (Fig. 5 d, e): stout; coxal plate rectangular, bilobate, about 3.1 times as long as wide; basis linear oblong, about 1.8 times as long as wide, with 3 and 6 small setae on anterior and posterior margins, respectively, and 2 long setae on anterodistal corner; ischium as long as wide, with 2 long setae on anterodistal corner; merus about 2.4 times as long as wide, posterior margin just slightly protruding forward, with 2 spines on posterior margin, 1 large spine-like seta accompanied by several small setae on posterodistal corner, with 3 groups of long setae on anterior margin and 1 large spine-like setae accompanied by several small setae on anterodistal corner; carpus shorter than merus, about 2.3 times as long as wide, linear, with straight lateral margins, with 3 groups of long simple setae on posterior margin and 3 long simple setae on anterodistal corner, with 6 large spine-like setae on posterodistal corner; propodus linear, slender, about 2.6 times as long as wide, with straight lateral margins, with 3 small spines accompanied by small setae on anterior margin and 1 spine accompanied by some setae on anterodistal corner, posterior margin smooth, unarmed, with 4 long strong spines and several small setae on posterodistal corner; dactylus (Fig. 5 e) slender, curved, about 6 times as long as wide, about twice shorter than the longest spines on posterodistal corner of propodus, with 1 penicillate seta on posteroproximal margin and 1 seta subdistally.
Pereopod 6 (Fig. 5 f): longer than pereopod 5; coxal plate shallow, bilobate, anterior lobe with 2 small setae on ventral margin; basis dilated, expanded in proximal part, about 1.7 times as long as maximal width, with 6 small setae on anterior and 1 long simple setae accompanied with several small setae on anterodistal corner, with 8 small setae on posterior and 1 long simple submarginal seta on posterodistal corner; ischium as long as wide, with 2 long setae on anterodistal corner; merus about 3 times as long as wide, posterior margin just slightly expanded and protruding forward, with 2 groups of spine-like setae and 1 simple seta on anterior margin, 2 large spine-like setae on anterodistal corner, with 3 spine-like setae on posterior margin and 1 strong spine on posterodistal corner; carpus shorter than merus, about 3 times as long as wide, linear, with straight lateral margins, with 3 groups of long simple setae on anterior margin and 3 long simple setae on anterodistal corner, with 1 small setae on posterior margin and 3 large setae on posterodistal corner; propodus linear, slender, about 4.5 times as long as wide, with straight lateral margins, with 1 double long strong spine on anterior margin and 1 spine accompanied by some setae on anterodistal corner, posterior margin smooth, unarmed, with 4 long and several small seta on posterodistal corner; dactylus slender, curved, about 6 times as long as wide, about twice shorter than the longest spines on posterodistal corner of propodus, with 1 penicillate seta on posteroproximal margin and 1 seta subdistally.
Pereopod 7 (Fig. 5 g, h): coxal plate small, suboval, about 1.8 times as long as maximal width, with 1 seta on posterodistal corner; basis expanded posteriorly, about 1.4 times as long as wide, progressively wider towards posterodistal, with 6 and 16 small spines on anterior and posterior margins, respectively, with 3 long setae on anterodistal corner; ischium slightly wider than long; merus expanded posteriorly, with 2 small spines accompanied with long setae on anterior margin and 3 long spine-like setae on anterodistal corner, with 4 strong spines on posterior margin and 1 strong spine on posterodistal corner; carpus shorter than merus, linear, about 4.0 times as long as wide, with straight lateral margins, with 2 groups of long simple setae on anterior margin and 3 long simple setae on anterodistal corner; posterior margin smooth, with 1 small seta and 2 strong spine-like setae on posterodistal corner; propodus linear, slender, about 5.4 times as long as wide, with straight lateral margins, with 2 pairs of spinelike setae on anterior margin and 2 long spines accompanied by several small setae on anterodistal corner, posterior margin smooth, unarmed, with 1 small seta and 2 long and 1 medium spine-like setae on posterodistal corner; dactylus (Fig. 5 h) slender, curved, about 7.2 times as long as wide, with 1 penicillate seta on posteroproximal margin and 1 seta subdistally.
Epimeral plates: plate 1 (Fig. 6 a) bare, with 3 small setae on posterior margin, posteroventral corner with minute projection; plate 2 (Fig. 6 b) with 7 long setae on ventral margin and 3 small setae along posterior margin, posteroventral corner with minute projection; plate 3 (Fig. 6 c) with 3 submarginal setae on ventral margin and 1 small seta on posterior margin, posteroventral corner rounded, with minute projection.
Pleopods 1–3 (Fig. 6 e): peduncles nearly quadrate, with 2 coupling hooks in retinacula on inner margins (Figs 6 f, 7 e), outer margins with 7 – 8 plumose setae in pleopod 1, 3 plumose setae in pleopod 2, and without plumose setae in pleopod 3 (Fig. 6 e); inner and outer rami fringed with plumose setae.
Uropod I (Fig. 6 g): peduncle stout, about 3.8 times as long as wide, slightly longer than rami, with 1 large submarginal ventroproximal spine, 3 spines on outer and inner margins, 1 large and 1 small spines on both outer and inner distal corners, respectively; outer ramus as long as inner ramus, about 9.6 times as long as wide, with 3 long simple spines on outer margin and 4 terminal spines distally, inner margin unarmed; inner ramus about 8.2 times as long as wide, with 2 and 1 spine on outer and inner margins, respectively, 3 large and 1 small terminal spine distally.
Uropod 2 (Fig. 6 h, i): about 0.5 times as long as uropod 1; peduncle relatively stout, about twice as long as wide, with 2 spines on outer margin, 2 spines on outer distal corner, and 2 spines on inner distal corner; outer ramus about as long as peduncle, equal to inner ramus, with a pair of spines on outer margin and 1 submarginal spine on inner margin, with 4 stout terminal spines; inner ramus with 2 spines on outer margin and 1–2 submarginal spines on inner margin, with 4 stout terminal spines.
Uropod 3 (Fig. 6 j): much enlarged, about 2.5 times longer than uropods 2–3; peduncle about 1.6 times as long as wide, about 0.35 of the length of proximal article of outer ramus, with 2 pairs of small spines on inner margin and 1 submarginal groups of 3 spines on outer margin, 6 spines accompanied by small setae on inner distal corner, and 3 spines on outer distal corner; inner ramus small, scale-like, about 0.10 times as long as outer ramus, and twice smaller than peduncle, with 2 small spines distally; proximal article of outer ramus with 6 small spine-like setae on outer margin, 7 spines on inner margin, 2 groups of spines on facial surface, 5 spines and several long setae on outer distal corner, and 3 spines and several long setae on inner distal corner; terminal article of outer ramus suboval, about 4.7 times as long as wide, slightly shorter than proximal article, with 3 small spine-like setae on outer margin, 3 small spines accompanied by setae on inner margin, 1 group of submarginal facial setae and 4 long slender terminal setae apically.
Telson (Fig. 6 d): about 1.2 times as long as wide, cleft almost reaching base; lobe subovate, with 1 large subdistal spine-like setae, accompanied with 1 small setae and pair of long penicillate setae on dorsal surface.
Coloration. Body coloration of live animals varies from completely white to light yellow (see Fig. 1 c).
Body size. The largest collected female has bl. 8.5 mm.
Habitat and ecology. The species was found in a heavily silted substrate at a depth of about 1–1.2 m, near the shore in the estuarine (estuarine) part exposed to tides. Unidentified burrowing ghost shrimps (Decapoda: Axiidea: Callianassidae) and alpheid shrimp Potamalpheops sp. (Decapoda: Caridea: Alpheidae) were found together with amphipods.
Distribution. Presently known only from the type locality, the mouth of the Bé River, Nha Trang City, Khánh Hòa province, Việt Nam (Fig. 1).
Taxonomic remarks. The new species is unique by the combination of several features 1) weakly but developed eyes, which are also present in Victoriopisa ryukyuensis Morino, 1991 from Japan (Morino, 1919), Victoriopisa chilkensis (Chilton, 1921) from India (Chilton, 1921), Victoriopisa tinggiensis Lim, Azman & Othman, 2010 from Johor, Malaysia (Lim et al., 2010) and Victoriopisa bruneiensis Hossain & Hughes, 2016 from Brunei, South China Sea (Hossain & Hughes, 2016) and 2) the presence of excavation on dactylus of gnathopod 2, which is also present only in V. chilkensis (see Chilton, 1921; Karaman, 1984b) and V. bruneiensis (Hossain & Hughes, 2016) among the abovementioned species.
The morphologically closest species, V. chilkensis, originally described from Chilika (Chilka) Lake, India (Chilton, 1921) and lately recorded from other localities in India (see Karaman, 1984b), also having eyes and excavation on dactylus of gnathopod 2, can be separated from the new species by the presence of dense setation of the articles 1–2 of antenna 1, shorter accessory flagellum on antenna 1, slightly overreaching the midlength of article 1 of the main flagellum, narrower epimeral plate I and more slender dactyli of pereopods 3–7. We suppose that the previous reference on the presence of V. chilkensis in Vietnam (see Dang & Le, 2011) belong to Victoriopisa nhatrangensis sp. nov.
At the same time, V. bruneiensis is characterized by the presence of a tuft of setae on distodorsal margin of article 2 of antenna 1 and significantly expanded distoventral margin of gnathopod 1, which is also characteristic to Victoriopisa cangio sp. nov. described below, slenderer article 1 of antenna 1, deeper excavation on dactylus of gnathopod 1 and different proportions in pereopods 2–7, especially pereopods 2 and 5 (see Hossain & Hughes, 2016: Fig. 9). However, this species is closely related to the species described here, especially to Victoriopisa cangio sp. nov. (see below).
Other abovementioned species can be clearly separated by the following features: V. tinggiensis can be separated by the presence of an anteroventral notch on the head, which is also present in Victoriopisa cusatensis Joseph, Nandan & Jayachandran, 2018 and Victoriopisa multiartus Zhao, Liu & Hou, 2016 (see Zhao et al., 2016; Joseph et al., 2018). Victoriopisa multiartus, together with the other known species Victoriopisa from Vietnam, Victoriopisa ovata (Dang & Le, 2005) from Hải Phòng, northern Vietnam (Dang & Le, 2005), are characterized by broad distal segment of uropod 3, which is almost oval in form, separating these species from other congeners (see Dang & Le, 2005; Zhao et al., 2016). Victoriopisa ryukyuensis Morino, 1991 and Victoriopisa australiensis (Chilton, 1923) are characterized with greatly posteriorly expanded merus and basis of pereopod 7 as well as distinctly produced epimeral plate 3 (see Morino, 1991; Lowry & Springthorpe, 2005), which easily separated these species from Victoriopisa nhantrangensis sp. nov.
From morphologically similar Victoriopisa wadai Ariyama, 2015 known from the Shikoku Island of Japan (see Ariyama, 2015), the new species can be separated by the presence of eyes, longer accessory flagellum of antenna 1, reaching the distal margin of the article 1 of flagellum, different form of ventral margin of propodus (chela) of gnathopod 2 without such deep excavation as present in V. wadai (see Ariyama, 2015: Figs 13, 14) and the presence of ventral excavation on dactylus of gnathopod 2.
Victoriopisa marina Lowry & Springthorpe, 2005 and Victoriopisa cusatensis Joseph, Nandan & Jayachandran, 2018 are characterized with greatly expanded article 1 of antenna 1 (see Lowry & Springthorpe, 2005; Joseph, 2018), clearly separating the species from the new ones.
For the distinguishing features from Victoriopisa cangio sp. nov. see below.
GenBank accessory numbers. OM002615, OM002616.
Genetic data. The obtained sequences allowed to compare Victoriopisa nhatrangensis sp. nov. with the only species of the genus, V. chilkensis, deposited in GenBank (MT184233, MK526893, MK526894). Both species forms a well-separated clade within the family Eriopsidae, but show a genetic divergence of about 23.6±0.022% for the COI mtDNA gene marker. We believe that such high genetic divergence is associated with the absence of a planktonic larva in amphipods, and therefore the species characteristic of mangrove communities have a rather local distribution and are well isolated.
description: Published as part of Marin, Ivan N. & Palatov, Dmitry M., 2022, Two new species of the genus Victoriopisa Karaman & Barnard, 1979 (Crustacea: Amphipoda: Eriopisidae) from mangrove communities of Vietnam with a review of previous records, pp. 129-152 in Zootaxa 5094 (1) on pages 132-142, DOI: 10.11646/zootaxa.5094.1.5, http://zenodo.org/record/5964945