Macrobrachium saengphani Saengphan & Panijpan & Senapin & Laosinchai & Suksomnit & Phiwsaiya 2020, sp. nov.
Creators: name: Saengphan, Nukul
name: Panijpan, Bhinyo
name: Senapin, Saengchan
name: Laosinchai, Parames
name: Suksomnit, Auaree
name: Phiwsaiya, Kornsunee
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Palaemonidae
Macrobrachium
Macrobrachium saengphani

description: Macrobrachium saengphani, sp. nov.
(Figs. 2–7)
Material examined. Holotype: male (CL 6.5 mm), 16 January 2017, Lao River, Tha Sai subdistrict, Mueang district, Chiang Rai Province (19°52.098′ N, 99°51.478′ E). Paratypes: 4 males (CL 5.8–6.5 mm), same location and date as holotype. Others: 3 males (6.2–6.5 mm) and 4 females (6.8–9.4 mm), 15 January 2017, Ing River, Si Don Chai subdistrict, Chiang Khong district, Chiang Rai Province (20°12.193′ N, 100°26.843′ E); 3 males (6.0– 6.6 mm) and 6 females (9.0– 11.5 mm), 15 January 2017, Kok River, Ban Saeo subdistrict, Chiang Saen district, Chiang Rai Province (20°12.854′ N, 100°05.282′ E).
Largest male: total length 31.0 mm, carapace length 6.6 mm, smaller than fully grown female (fig. 2).
Largest ovigerous female: total length 49.0 mm, carapace length 11.5 mm.
Description. (Fig. 3A) Rostrum: straight, slender, upturned distally, extending beyond or slightly shorter than end of scaphocerite, length subequal to carapace; upper part having 6–8 teeth, 1–2 (usually 2) teeth behind postorbital margin; lower part having 4–5 (usually 4) teeth; distance between first anterior tooth and second one being longer than varying distances between succeeding teeth.
Antennal spine: well developed with pointed end and situated below orbital angle (suborbital angle); hepatic spine of size similar to that of antennal spine and located slightly behind and lower than antennal spine; paired hepatic spines on carapace situated between upper first and second rostral teeth.
Carapace: smooth; thoracic sternite of fourth segment with small median process; sixth abdominal somite 1.27–1.55 times as long as fifth; upper telson (fig. 3B) smooth and 1.47–1.61 times the length of sixth segment with 2 dorsal paired spines; tail tapering with pointed end (median spine) and bulging slightly at mid-section, each side flanked by 2 spines, outer lateral spine and inner intermediate spine; several pairs of plumose setae found between 2 flanking spines; lateral spines similar in size to dorsal spines; well-developed intermediate spines 2–3 times the length of median spine; first, second and third abdominal sternites having transverse ridges with median teeth; third abdominal having smaller median tooth; preanal region unarmed.
Eyes: well developed, cornea diameter as long as stalk.
Basal segment of antennular peduncle: broad, stylocerite distinctly pointed, reaching about one-third of basal segment; anterolateral tooth reaching about middle of second segment; second segment as long as third.
Scaphocerite (fig. 3C): length 3.15 times the width, outer lateral side straight.
Epistome (fig. 3D): bilobed by deep depression.
Mandibular palp (fig. 3E): slender with three segments, incisor process robust.
Maxillular palp (fig. 3F): bilobed, upper lobe slender without apical and subapical setae, lower lobe stout with distal blunt knob bearing short sinuous apical seta.
Maxillary palp (fig. 3G): simple without distal setae, basal endite deeply bilobed, scaphognathite normal.
First maxilliped (fig. 3H): palp without setae, basal and coxal endites distinct, flagellum of exopod with numerous distal plumose setae, epipod bilobed.
Second maxilliped (fig. 3I): with normal endopod, flagellum with numerous distal setae, epipod simple.
Third maxilliped (fig. 3J): with robust endopod, exopod with numerous distal plumose setae, reaching extremity of ischiomerus.
First pereiopod (fig. 3K): slender, reaching nearly end of scaphocerite, equal in length, similar in form; palm as long as finger, carpus 2.27 times as long as chela, merus shorter than carpus.
Second pereiopod (fig. 3L): smooth, carpus reaching slightly beyond scaphocerite, subequal to half of body length; equal in length, similar in form; palm, carpus, merus, ischium smooth; moving fingers bending upward, subequal to palm length, 2 small teeth at proximal half of cutting edge; fixed finger having acute end, proximal half of cutting edge armed with 2 or 3 small teeth, third tooth, if any, proximally adjacent to and smaller than second; both fingers curving inward, tips crossing without gap when fingers closed; both sides of cutting edge having stiff setae (fig. 3M), female with stiff setae concentrating proximally and delicate setae at tip, male with stiff setae throughout (fig. 4); carpus longer or as long as chela.
Last three pereiopods: slender, similar in form; propodus, carpus, and merus covered with spinules and setae.
Third pereiopod (fig. 3N): not reaching the end of scaphocerite, propodus 2.3–3.0 times as long as dactylus with 7 movable spines on postero-lateral margin.
Fifth pereiopod: slightly slenderer than third, reaching distal margin of scaphocerite (end of dactylus and end of scaphocerite terminating at equidistance).
First pleopod: endopod not reaching distal half of exopod, inner margin concave, outer margin slightly convex.
Appendix musculina of male: longer, stouter than appendix interna with numerous stiff setae.
Uropodial diaeresis: with inner movable spine (fig. 3O) shorter than outer angle.
Ovigerous females: with eyed eggs 1.15×1.64 – 1.23× 1.75 mm in diameter.
Etymology. The species is named after the first author. The name, thus, is a noun in the genitive singular.
Molecular phylogeny. DNA sequences: COI 668 base pairs (bp); majority of 18S 1446 bp; consensus alignment of 18S 1452 bp.
Phylogenetic relationship (fig. 5): Macrobrachium suphanense and M. sintangense (de Man, 1898) form monophyletic clade (clade 1), posterior probability 1; M. chainatense and M. niphanae Shokita & Takeda, 1989 form monophyletic clade (clade 2), posterior probability 1; clade 2 and M. dienbienphuense Dang & Nguyen, 1972 form monophyletic clade (clade 3), posterior probability 1; clade 1 and clade 3 form monophyletic clade (clade 4), posterior probability 0.70; clade 4 and M. saengphani sp. nov. form monophyletic clade (clade 5), posterior probability 0.76; M. lanchesteri and M. rosenbergii form monophyletic clade (clade 6), posterior probability 1; clades 5 and 6 are sisters, posterior probability 1.
description: Published as part of Saengphan, Nukul, Panijpan, Bhinyo, Senapin, Saengchan, Laosinchai, Parames, Suksomnit, Auaree & Phiwsaiya, Kornsunee, 2020, Morphology and molecular phylogeny of Macrobrachium saengphani sp. nov (Decapoda: Palaemonidae) from Northern Thailand, pp. 531-542 in Zootaxa 4868 (4) on pages 534-536, DOI: 10.11646/zootaxa.4868.4.4, http://zenodo.org/record/4443533