Patrus corpulentus ( Régimbart, 1884 ), Borneo

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 : 570

publication ID	https://doi.org/ 10.11646/zootaxa.4991.3.8
publication LSID	lsid:zoobank.org:pub:F0FAE07E-4A90-4602-BCC5-6D80E158BB6C
persistent identifier	https://treatment.plazi.org/id/03BC87C1-FFE3-2242-0CC0-7AB4FB2A54D4
treatment provided by	Plazi
scientific name	Patrus corpulentus ( Régimbart, 1884 )
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Patrus corpulentus ( Régimbart, 1884)

( Figs. 2B View FIGURE 2 , 3B View FIGURE 3 , 4B View FIGURE 4 , 6 View FIGURE 6 , 14A View FIGURE 14 )

Orectochilus corpulentus Régimbart, 1884: 411 (original description)

Orectochilus corpulentus Régimbart, 1884 : Régimbart 1888: 619 (description of male)

Orectochilus (Patrus) corpulentus Régimbart, 1884 : Hatch 1926: 453

Type localities. Java and Borneo [both likely in error] .

Type material examined. SYNTYPE female ‘ Java [yellow label, black border, handwritten black ink]’ ‘Badiu [white label, black border, handwritten black ink]’ ‘Corpulentus / Regb. Type [white label, handwritten black ink]’ ‘ Dr Régimb. / vidit 1883. [white label, typed black ink]’ ‘Ex COLL. / E. WEHNCKE [white label, typed black ink]’ ‘ corpulentus Régbt. / java type! [being label, yellow border, handwritten black ink]’ ‘ SYNTYPE [red label, typed black ink]’ ‘ SYNTYPE / Orectochilus / corpulentus Régimbart , / 1884 [white label, typed black ink]’ ‘MNHN / EC10141 [white label, typed black ink]’.

Other material examined. MYANMAR: Tenasserim region , 1838–1839, 1 male ( NMPC) . THAILAND: Surat Thani Province: Khao Sok Natl. Park., Mae Yai Waterfall , 8°52’59.6”N 98°29’58.4”E, 287 m a.s.l., 25.V.2005, leg. A. Vitheepradit, R.W. Sites & T. Prommi, L-797, 2 females ( UMC, THNHM) GoogleMaps .

Diagnosis. Size: Male: 12.0 mm; females: 9.0– 9.5 mm; body form in lateral view strongly dorsoventrally convex, evenly weakly depressed anteriorly and posteriorly; elytral glabrous region of male not cordiform ( Figs. 2B View FIGURE 2 , 6A View FIGURE 6 ), along suture extending ca. 6/7 length of elytra, lateral margins rounded, being expanded after humeral region to just wider than pronotal glabrous region then attenuated apically; female elytral glabrous region ( Figs. 3B View FIGURE 3 , 6C View FIGURE 6 ) similar to male; elytral apex weakly rounded (female) or narrowly rounded (male) with apicolateral sinuation, epipleural angle distinct and rounded; male protibia club-shaped ( Fig. 4B View FIGURE 4 ) strongly curved basally, without constriction, protibial apex truncate with prominent distolateral angle; male protarsus ca. 1/2 of protibia ( Fig. 4B View FIGURE 4 ), protarsomeres width gradually decreasing apically, first protarsomere 2× length of second; mesoventrite of female without medial pit (not examined in male); aedeagus ( Fig. 6B View FIGURE 6 ) with median lobe evenly tapered, apex narrowly rounded; female reproductive tract ( Fig. 6E View FIGURE 6 ) without additional sclerotized structure between gonocoxae ( Fig. 6D View FIGURE 6 ), fertilization duct as in Fig. 6F View FIGURE 6 .

Differential diagnosis. This species can be distinguished from all other known members of the P. landaisi species group in Thailand by the shape of the glabrous region of the elytra ( Figs. 2B View FIGURE 2 , 3B View FIGURE 3 ), and by having the elytral apex narrowly or weakly rounded with visible apicolateral sinuation ( Fig. 6A, 6C View FIGURE 6 ). Both males and females of the other species lack apicolateral sinuation to the elytral apex and they have their glabrous region extending a relatively shorter distance along the elytra suture, up to 7/9 elytral length. These features, combined with P. corpulentus being the only P. landaisi group species found at lower elevation in Thailand, should allow its unambiguous identification.

Distribution. Patrus corpulentus was originally described from Java, potentially in error ( Régimbart 1884; Ochs 1930), and Borneo, potentially in reference to a separate species (see below). Subsequent records for this species are from Tenasserim and the Karen hills regions of Myanmar ( Régimbart 1891; Zimmermann 1917). It had also been recorded in Thailand from Ranong Province by Régimbart (1892), and subsequently in Phuket Province by Ochs (1927). Recently two female specimens were found together within Surat Thani Province ( Fig. 14A View FIGURE 14 ). Unlike the other P. landaisi species group members in Thailand, P. corpulentus appears to occur at low elevations rather than in high-elevation mountain streams.

Discussion. The original description of P. corpulentus ( Régimbart 1884) was based on five female specimens: one from Java, one from Borneo, and three without locality indications. Régimbart later (1888, 1892) described specimens of what he considered to be males of P. corpulentus from Tenasserim and the Karen hills region of Myanmar. In the same publications he clearly distinguishes these last specimens, the female from Java and the unlabeled females, from the single female from Borneo as belonging to different “varieties”. Therefore, it seems likely that the syntype series may consist of two different species, one from the Malay peninsula (accepting “Java” as an erroneous locality), and another from Borneo (P. Mazzoldi pers. comm.). We examined the syntype female labeled as being from Java and it is indeed conspecific to the specimens we collected from Surat Thani Province, thus we consider them as belonging to P. corpulentus sensu Régimbart (1884 [in part], 1888, 1892).