Patrus apicalis ( Régimbart, 1891 )

Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W. & Sangpradub, Narumon, 2021, Review of the Patrus landaisi species group from Thailand with description of three new species (Coleoptera, Gyrinidae), Zootaxa 4991 (3), pp. 561-591 : 566

publication ID	https://doi.org/ 10.11646/zootaxa.4991.3.8
publication LSID	lsid:zoobank.org:pub:F0FAE07E-4A90-4602-BCC5-6D80E158BB6C
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scientific name	Patrus apicalis ( Régimbart, 1891 )
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Patrus apicalis ( Régimbart, 1891)

( Figs. 2A View FIGURE 2 , 3A View FIGURE 3 , 4A View FIGURE 4 , 5 View FIGURE 5 , 13B View FIGURE 13 , 14A View FIGURE 14 )

Orectochilus apicalis Régimbart, 1891: 548 (original description)

Orectochilus (Patrus) apicalis Régimbart, 1891 : Ochs 1930: 20

Type locality. Karen Hills , Myanmar .

Type material examined. HOLOTYPE female ‘Carin / Asciui Ghecù / 1200–1400 m. / L.Fea III–88 [beige label, handwritten black ink]’ MSNG Holotype DSCN0243. Additional label information not provided to authors.

Other material examined. THAILAND: Chiang Mai Province: Mae Kam Pong Stream, Huay Kaew Subdistrict, Mae On District , 18°51’58.3”N 99°21’09.4”E, 1011 m a.s.l., 15.V.2017, leg. B. Suksai, C. Jaitamart & T. Paotajai, 1 male ( THNHM) GoogleMaps . Chiang Rai Province: Nam Kuen Stream, Ban Huai Nam Kuen, Mae Chedi Subdistrict , Wiang Pa Pao District , 19°07’22.3”N 99°19’43.3”E, 1327 m a.s.l., 25.V.2017, leg. P. Sapewisut, 3 males, 3 females ( KKU) GoogleMaps ; same locality except for, 11.XI.2018, leg. B. Suksai, P. Sapewisut & S. Kullasoot, 4 males, 7 females ( GTGC, KKU, THNHM, UMC) GoogleMaps ; same locality except for, 3.V.2019, leg. B. Suksai, P. Sapewisut & N. Plangklang, 1 male ( THNHM) GoogleMaps , 4 females ( THNHM, GTGC) GoogleMaps . Nan Province: Khun Sathan Natl. Park., Ban Mueng Li, Mueng Li Subdistrict , Na Muen District , 18°15’08.44”N 100°29’35.77”E, 786 m a.s.l., 29.V.2017, leg. P. Sapewisut, 1 male ( THNHM) GoogleMaps ; Mae Charim Natl. Park., Huay Nampangyaekkwar, Mae Charim Subdistrict , Mae Charim District , 18°48’46.58”N 101°04’10.21”E, 461 m a.s.l., 3.I.2013, leg. K. Rattanachan, 3 females ( NHMW) GoogleMaps .

Diagnosis. Size: Male: 13.0–14.0 mm, female: 10.0– 10.9 mm; body form in lateral view weakly dorsoventrally convex; elytral glabrous region of male ( Figs. 2A View FIGURE 2 , 5A View FIGURE 5 ) cordiform, along suture extending ca. 7/9 length of elytra, laterally expanded in anterior 2/3 to considerably wider than pronotal glabrous region, posterior 1/3 strongly acuminate with rounded margins; female elytral glabrous region ( Figs. 3A View FIGURE 3 , 5E View FIGURE 5 ) dissimilar to male, broad for nearentire length occupying 10/11 elytral width, lateral margins nearly-straight for 3/4 length creating parallel-sided appearance, abruptly acuminate medially in posterior 1/4, posterolateral corners produced into points, posterior margin evenly convex toward suture; in lateral view width of pubescent margin at humeral region nearly equal to that extending posterior; elytral apex of both sexes similar, obliquely truncate without apicolateral sinuation, epipleural angle distinct, weakly rounded; male protibia wedge-shaped ( Fig. 4A View FIGURE 4 ), without basal constriction, protibial apex obliquely truncate with or without prominent distolateral angle; male protarsus ca. 3/4 length of protibia ( Fig. 4A View FIGURE 4 ), protarsomeres 1–4 mostly similar in width; mesoventrite of male with medial pit; aedeagus ( Fig. 5B–D View FIGURE 5 ) with median lobe in basal 2/3 weakly tapered, weakly constricted medially, parallel-sided in apical 1/3 before acumination, apex strongly constricted to a needle-like point extending 1/5 length, very weakly constricted in lateral view ( Fig. 5C View FIGURE 5 ); female reproductive tract ( Fig. 5G View FIGURE 5 ) without additional sclerotized structure between gonocoxae ( Fig. 5F View FIGURE 5 ), fertilization duct as in Fig. 5H View FIGURE 5 .

Differential diagnosis. Patrus apicalis is most similar to P. subapicalis , as the latter was previously considered to be a subspecies of the former. P. apicalis can be distinguished by the mesoventrite of the male having a medial pit, which is absent in both sexes of P. subapicalis . Males of these two species can be also distinguished by the shape of the median lobe of the aedeagus, which in P. apicalis has the apex with a more needle-like point ( Fig. 5B View FIGURE 5 ), compared to P. subapicalis in which the apex is relatively less constricted and has a triangular tip ( Fig. 12B View FIGURE 12 ). Females of both species are similar, but can be separated by the shape of the elytral glabrous region, wherein the lateral margin in P. apicalis appears more rounded for 3/4 of its length ( Fig. 5E View FIGURE 5 ), compared to that of P. subapicalis ( Fig. 12E View FIGURE 12 ) which has a nearly straight lateral margin that creates a more parallel-sided appearance to the elytral glabrous region. The posterior margin of the elytral glabrous region further differs between the two species, having a greater concavity in P. apicalis ( Fig. 5E View FIGURE 5 ) relative to P. subapicalis ( Fig. 12E View FIGURE 12 ). The female of P. apicalis is also similar to that of P. nanensis sp. nov. but can be separated from the latter by the posterior margin of the elytral glabrous region being more rounded in appearance ( Fig. 5E View FIGURE 5 ) compared to P. nanensis sp. nov. which has the posterior margin with a more oblique and angular appearance to its convexity ( Fig. 9E View FIGURE 9 ).

Distribution. Previously known from the Karen Hills region of Myanmar and northern Laos ( Peschet 1923), this species is here recorded from Thailand for the first time. Within Thailand, it can be collected in slow recesses of high elevation streams ( Fig. 13B View FIGURE 13 ) across the northwestern mountains ( Fig. 14A View FIGURE 14 ). This species has been found together with P. salvazai in streams in Chiang Rai Province ( Fig. 13B View FIGURE 13 ).