Haustorioides furotai Ogawa, 2021

Ogawa, Hiroshi, Takada, Yoshitake & Sakuma, Kay, 2021, A New Species of the Sand-burrowing Dogielinotidae, Haustorioides furotai, from Tokyo Bay, Japan (Crustacea: Amphipoda), Species Diversity 26, pp. 65-78 : 68-76

publication ID	https://doi.org/ 10.12782/specdiv.26.65
publication LSID	lsid:zoobank.org:pub:7B7942B9-1754-4D12-BD2E-4D962AEED65C
persistent identifier	https://treatment.plazi.org/id/2D3FDA8D-EE82-49D4-97F5-20BF2B991B27
taxon LSID	lsid:zoobank.org:act:2D3FDA8D-EE82-49D4-97F5-20BF2B991B27
treatment provided by	Felipe
scientific name	Haustorioides furotai Ogawa
status	sp. nov.

Treatment

Haustorioides furotai Ogawa View in CoL , sp. nov.

[New Japanese name: Usuge-naminori-sokoebi] ( Figs 2–8 View Fig View Fig View Fig View Fig View Fig View Fig View Fig )

Material examined. Holotype: NSMT-Cr 28350, male (7.2 mm), Banzu tidal flat, Kisarazu City , Chiba Prefecture, 35°25′11″N, 139°52′36″E – 35°24′46″N, 139°53′47″E, intertidal, 17 February 2018, coll. H. Ogawa. GoogleMaps Paratypes: NSMT- Cr 28351, ovigerous female (7.2 mm), same data as holotype GoogleMaps . NSMT-Cr 28352, immature female (9.3 mm), same data as holotype GoogleMaps . NSMT-Cr 28355, male (8.0 mm), NSMT- Cr 28353, male (4.0 mm), NSMT-Cr 28354, ovigerous female (4.0 mm), and NSMT-Cr 28356, female (6.1 mm), Banzu tidal flat, 35°25′00″N, 139°51′00″E – 35°24′59″N, 139°51′59″E, upper subtidal, 17 August 2010, coll GoogleMaps . T. Furota , R . Suzuki , and H . Ogawa . NSMT-Cr 28357, ovigerous female (2.8 mm), Banzu tidal flat, 900 m offshore from the mouth of Obitsu River, 35°24′11″N, 139°53′00″E – 35°24′59″N, 139°53′18″E, intertidal, 25 June 2010, coll GoogleMaps . H GoogleMaps . Ogawa. NSMT-Cr 28358, male (2.8 mm), Banzu tidal flat, 24 June 2010, coll . M GoogleMaps . Taru. NSMT-Cr 28359, female (7.8 mm), NSMT-Cr 28360, female (7.5 mm), CBM-ZC 16177, female (8.5mm), CBM-ZC 16178, female (8.2 mm), NSMT-Cr 28361, male (5.5 mm), NSMT-Cr 28362, male (6.8 mm), CBM-ZC 16179, male (5.1 mm), and CBM-ZC 16180, male (6.3mm), Banzu tidal flat, 35°25′11″N, 139°52′36″E – 35°24′46″N, 139°53′47″E, 9 March 2019, coll . H GoogleMaps . Ogawa.

Diagnosis. Flagellums of antennae 1–2 with marginal setae on each article, 0–2 long (crossing, or reaching distal margin of next article) setae ventrodistally, and medium length (not reaching distal margin of next article) setae dorsodistally and ventrodistally. Labrum not proboscoid, without mid-medial seta, distally subtruncated. Outer plate of maxilliped acute angled. Coxal plates 1–4, each anterior margin with 0–5 setae. Anterodistal lobes of each merus pereopods 3 and 4 overlapped to each carpus. Dactyli of all pereopods claw-shaped (in pereopods 3 and 4, anterior margin curved, posterior margin straight; in pereopods 5–7, anterior margin straight, posterior margin curved) poorly setose; each dactylus of pereopods 5–7 about 0.6 times of each propodus in lengths. Pleopods with 4–7 retinacula. Epimeral plate 1 with a small tooth, epimeral plates 2 and 3 with straight tooth. Telson uncleft with a ridge reaching distal margin.

Description of male (based on holotype, NSMT-Cr 28350). Body smooth ( Fig. 2 View Fig ). Rostrum distinct, medium. Eyes medium size, irregular ovoid. Lateral cephalic lobe slightly rounded triangular.

Antenna 1 ( Fig. 3A View Fig ): slightly shorter than antenna 2, flagellum 7-articulated, each article with marginal setae (<10) include 0–2 long (crossing distal margin of next article) setae ventrodistally. 1 or 2 aesthetascs on ventrodistal margin of each article except first and last one. Antenna 2 ( Fig. 3B View Fig ): flagellum 9-articulated; each article with marginal setae (<20), include 0–2 long (crossing distal margin of next article) setae ventrodistally, except dorsolateral side.

Labrum ( Fig. 3C View Fig ): usual structure, not proboscoid, without mid-medial seta, distally subtruncated. Mandible ( Fig. 3G, H View Fig ): ventral side of molar with long plumose seta, right lacinia mobilis with slender teeth, left lacinia mobilis with robust teeth, each lacinia mobilis followed by 3 or more plumose blades. Maxilla 1 ( Fig. 3E View Fig ): palp minute, inner lobe short, with 2 apical plumose setae. Maxilla 2 ( Fig. 3F View Fig ) and labium ( Fig. 3D View Fig ) usual structure.

Maxilliped ( Fig. 3I View Fig ): inner lobe distally truncated, with 3 distal robust setae, not extending beyond apex of outer lobe; outer lobe subtriangular, reaching to top of lateral margin of palp article 1, palp as generic character.

Coxal plates 1–4 deep, with 3–5 marginal setae anteriorly.

Gnathopod 1 ( Fig. 4A View Fig ): subchelate, basis with a seta on posterodistal corner; propodus with a hump and bifid spines on posterior corner of palm; palm with microscopic scalelike structures ( Fig. 4B View Fig ).

Gnathopod 2 ( Fig. 4C View Fig ): subchelate; basis with 2 long setae on posterior margin; carpus with 3 small setae on anterodistal corner; propodus 2.5 times as long as carpus, slightly inflated anteriorly, palm longer than 1.5 times of posterior margin.

Pereopods 3–4: each merus with sharp anterodistal lobe and overlapped to carpus; each merus and carpus with some setae on posterior margin; each dactylus without setae on posterior margin.

Pereopod 3 ( Fig. 4D View Fig ): basis with 2 distal long setae on posterior margin and 1 bundle of setae on posterodistal corner; ischium with 1 bundle of setae on posterodistal corner; carpus with 2 long setae on apex of anterior lobe; propodus with 2 bundles of setae on posterior margin and 1 bundle of setae on posterodistal corner.

Pereopod 4 ( Fig. 4E View Fig ): basis with 5 long setae on posterior margin and 1 bundle of setae on posterodistal corner; ischium with 1 bundle of short setae on posterodistal corner; carpus with 2 long setae on anterodistal lobe; anterior and posterior margins of propodus with setae.

Pereopods 5–7: each basis expanded posteriorly and lobed ventrally, short setae on anterior margins, and with tiny setae on posterior margins.

Pereopod 5 ( Fig. 5A View Fig ): ischium with 1 long distal seta on anterodistal corner; merus wider than long, expanded posterodistally and hanging carpus, with bundles of setae on posterior margin, with long distal setae and 5 spinous setae on posterior margin; carpus subrectangular, with bundles of setae on anterior margin, with bundle of setae containing 1 plumose seta on posterodistal corner; propodus with spinous setae on anterodistal corner, with 1 tiny and above 2 long spinous seta posterior margin; dactylus with 2 tiny setae on anterior margin.

Pereopod 6 ( Fig. 5B View Fig ): basis with 2 setae on anterior margin; merus with 3 bundles of setae on anterior margin, posterior margin with long setae and spinous setae, posterodistal lobe elongated; carpus with spinous setae on anterodistal corner, and with 1 long seta on posterodistal corner; dactylus with 1 long and 3 short setae.

Pereopod 7 ( Fig. 5C View Fig ): basis with 2 apical setae on anterodistal corner; ischium with 3 apical setae on anterodistal corner; merus with 1 bundle of setae on anterior and posterior margins; carpus with1 bundle of setae on anterior margin, with 1 bundle of setae on posterodistal corner; propodus with 2 bundles of setae on anterior and posterior margins, with bundles of setae including plumose and simple setae; dactylus with plumose and distal setae on anterior margin.

Epimeral plates 1–3 ( Fig. 6H View Fig ): each posterodistal corner toothed; epimeral plate 1 with a small tooth; epimeral plates 2 and 3 with straight teeth, elongated posteriorly; tooth on epimeral plate 2 subequal epimeral plate 3.

Pleopods 1–3 ( Figs. 6A–C View Fig ): each peduncle with facial fine setae and 6–7 retinacula; inner ramus 10–11 articulated; outer ramus 11–15 articulated ( Figs. 6D–F View Fig ).

Uropods 1–2: each ramus without setae. Uropod 1 ( Fig. 6I View Fig ) peduncle with 2 apical spinous setae. Uropod 2 ( Fig. 6J View Fig ) peduncle with 1 apical spinous seta. Uropod 3 ( Fig. 6K View Fig ): lacking rami, peduncle with 1 apical spinous seta and 3 tiny setae on dorsal margin.

Telson ( Figs. 6L, M View Fig ) fused, ridge reaching distal tip, with small facial setae.

Description of female (based on paratype, NSMT-Cr 28351). Similar to male except for the following characters ( Figs 7 View Fig , 8 View Fig ).

A hump on palm of gnathopod 1 weaker than that of male ( Fig. 7A View Fig ). Gnathopod 2 ( Fig. 7B View Fig ) carpus with 1 bundle of long setae on anterodistal corner, propodus almost same length to carpus, propodus palm slightly shorter than posterior margin.

Morphological variations. The new species exhibits morphological variations in the number of flagella of both antennae 1 (5 to 8-articulated) and 2 (6 to 9-articulated) and each pleopod (with 4 to 8 retinacula).

Coloration in life. Body whitish. Head deep brown posterodorsally. Eyes white with dark red spots. Both antennae pale yellowish-orange from article 2 of peduncle forward flagellum, and dorsodistal corner of peduncle article 1. Maxilliped yellowish-orange. Each pereosome and pleosome with wide brown band anteriorly.

DNA analyses. In the ML and NJ trees, all selected specimens of H. furotai are included in a monophyletic lineage ( Fig. 9 View Fig ). Uncorrected p -distances between H. furotai and congeners ( Table 2) are greater than the proposed threshold for amphipod species (3.5–4.4%: Rock et al. 2007; Witt et al. 2008; Hou et al. 2009; Tomikawa et al. 2018).

Distribution and habitat. Known only from the type locality inhabiting sandy mud bottom of intertidal to upper subtidal zones.

Etymology. The specific name is dedicated to Professor Toshio Furota, the first author’s supervisor at Toho University, and in honor of his substantial contributions to conservation ecology of tidal flats in Tokyo Bay.

The Japanese name of “usuge” refer to the species with poorly setose antennal flagellums and pereopodal dactyli in contrast to the majority of their congeners.

Remarks. The new species H. furotai can be distinguished from H. gurjanovae , H. magnus , and H. munsterhjelmi by the following characters: posterodistal tooth of epimeral plate 3 is elongate straightly (vs. curved posterodorsally); peduncles of uropods 1 and 2, each outer margin with less than 5 setae on outer margin (vs. with more than 5 setae) and telson uncleft (vs. cleft to medium).

Haustorioides furotai also can be distinguished from H. koreanus , H. latipalpus and H. nesogenes by the following characters: merus of pereopod 6, posterior margin with less than 20 setae (vs. with more than 20 setae); ventral margin of epimeral plates 2 without setae (vs. armed numerous setae); telson uncleft (vs. cleft to medium or with small notch).

Haustorioides furotai is similar to H. indivisus and H. littoralis in lacking a curved tooth on epimeral plates 2 and 3, each peduncle of uropod 1 and 2 with less than 5 spinous setae and uncleft telson; however, H. furotai differs from H. indivisus in labrum subtruncated distally (vs. distal margin emarginated), inner plate of maxilliped acute angled (vs. moderate broad and obtuse angled) and apex of reaching inner margin of palp article 1 (vs. outer margin of article of outer plate), and from H. littoralis in outer plate of maxilliped reaching (vs. far shorter) to top of outer margin of palp article 1 and each epimeral plate 2 and 3 with straight tooth posterodistally (vs. without elongated tooth).

Haustorioides furotai also shows similarities to H. japonicus in having straight teeth on posterodistal corner of epimeral plates 2 and 3 and uncleft telson, however differs in the labrum subtruncated distally (vs. distal margin slightly emarginated), triangular and slender outer plate of maxilliped (vs. moderate broad and rounded distally), posterior margin of pereopod 3 with no more than 10 (vs. more than 20) long setae, dactylus on pereopod 5–7 crow-shaped (vs. knife-shaped).