Semicerura bryophila Potapov & Sun, 2020

Potapov, Mikhail, Xie, Zhijing, Kuprin, Alexander & Sun, Xin, 2020, The genus Semicerura (Collembola; Isotomidae) in Asia, Zootaxa 4751 (1), pp. 105-118 : 106-111

Semicerura bryophila Potapov & Sun , sp. nov.

Figs 1, 3–13, 16–17, 38

Syn.: Semicerura bishopi sensu Martynova, 1969

Paratypes, 7 paratypes; China , Jilin province, Changbai Mts ; 41.847° N, 127.798° E; altitude ca 1100 m; May 2015; D. Wu leg. (kept in IGA). Russia : 4 paratypes; Far East , Primorski Krai, Ussuriysky Reserve , Komarovskoye Forest District; 23 Jul. 2016; N. Kuznetsova, M. Potapov, A. Kuprin leg. (kept in MSPU); trail to top of Grabovaya Nipple, 43.637° N, 132.350° E, mixed forest, mosses from tree. Russia : 3 paratypes; Far East , Primorski Krai, Lazovski district , in mountains nearby Preobrazheniye, Maralovaya River; altitude ca 600 m; 42.996 ° N, 133.902° E, 21 Sep. 2011; M. Potapov leg. (kept in SMNG); thin moss on stones in deciduous forest .

Other material. Russia, Far East, Primorski Krai. Surroundings of Vladivostok; 9 Sep. 1963; N. Bregetova leg.; moss from rotten tree stump and moss near spring. Shkotovski district , Falaza Mt. ; 43.101° N, 132.789° E; May 1978; L. Kutyreva leg.; poplar wood. Shkotovski district , Livadiysky Range , Pidan Mt. ; 43.067° N, 132.683° E; 20 Sep. 2004; M. Potapov leg.; burnt place, thin lichens on stones. Terneyski District , Sikhote-Alinski Reserve , Kabani station ; 45.13824° N, 135.88690° E; altitude ca 525 m; 08 Aug. 2017; N. Kuznetsova, A. Geraskina, A. Kuprin leg.; coniferous wood with Rhododendron , litter and rotten wood. Chuguevski District , Oblachnaya Mt. ; 43.695° N, 134.199° E; altitude ca 560 m and 1220 m; 19 Sep. 2018; A. Kuprin leg.; mixed cedar forest and spruce forest, rotten wood. Partizanski District , Olkhovaya Mt. ; 43.347° N, 133.656° E; altitude ca 1380 m; 20 Aug. 2018; M. Potapov, Y. Shveenkova and A. Kuprin leg.; spruce forest, rotten wood and litter .

Russia, Far East, Khabarovski Krai. Khekhtsyr Range (ca 25 km S Khabarovsk), near Korfovsky; 25 Apr. 2010; M. Potapov and E. Sokolova leg.; poplar forest, mosses on lower part of tree trunk. Verknebureinski area , western Badjal Range , Irungda River ; altitude about 1900 m; 23 Jun. 2014; A. Brinev leg.; alpine belt, moss and lichens. Lazo District , Ko Mt. ; 47.124° N, 136.611° E; altitude ca 500 m and 970 m; 01 Jul. 2018; A. Brinev leg.; mixed cedar forest (middle part of Katen spring) and spruce forest (upper part of Katen spring). Lazo District , Arsenyevskiye Granity Range, Arsenyeva Mt. , junction of Malinovy and Maly Katen; 46.844° N, 136.703° E; altitude ca 500 m and 900 m; 08 Jul. 2019; A. Brinev leg.; mixed cedar forest (500 m) and spruce forest (900 m), rotten wood .

Russia, Far East, Amurskaya Region. Amurskaya Region, Arkharinsky District, Khingansky Reserve; 10 km E Uril; 07 Oct. 2009; M. Babykina leg.; coniferous litter.

China, Jilin province, Fusong County, Manjiang town forest (foothills of Changbai Mts ); 41.96° N, 127.59° E; Mar. 2018; D. Wu leg.; Changbai Mts ; 42.086° N, 128.074° E; Sep. 2018; Z. Xie, M. Potapov and L. Chang leg.; coniferous forest .

Type material of Semicerura bishopi Maynard, 1951 . Holotype collected in the New York State of U.S.A. under the label “Type, Clifton N.Y., 22 Apr. 1947, on mossy log, E.A. Maynard. Semicerura bishopi ”. The slide is also labelled and listed under USNMENT 01539202 code on the website of Department of Entomology Collections of Smithsonian National Museum of National History.

Description. Body size 1.0– 1.3 mm. Body shape more stout than common for the subfamily, head large (Fig. 1). Abd. V and VI fused, without a wrinkle and with unclear break in chaetae cover. With strong black-blue pigment on corpus. Legs white (yellow in alcohol), posterior and lateral parts of head paler, often almost unpigmented, antennae moderately pigmented (Fig. 38). Integument smooth, without visible granulation. 8+8 ocelli, two anterior (A and B) enlarged and well visible, other with weak corneae and hardly visible ( Fig. 5 ). PAO smaller than nearest ocellus, 0.3–0.4 as long as Claw III. Ant. I on ventral side with 3–7 long thin s-chaetae and 2–3 short ones in more distal position. Ant. II and III with few s-chaetae. Ant. III organ normal, with a pair of blunt rods in a groove. Ant. IV without thickened s-chaetae, apical bulb absent. Subapical pin chaeta simple, subapical organite small, subapical micro s-chaeta as common for the family. Labrum with 4/554 chaetae, apical edge with 4 broad ridges. Maxillary outer lobe with trifurcate palp and 4 sublobal hairs. Labial palp with all apical papillae (A–E) and 15 guards, e7 absent. 5 proximal chaetae, of which 2 placed at medial line, posterior to papilla A ( Fig. 3 , marked as “Semic.”). Hypostomal chaeta H longer than h1 and h2. Basal fields of labium with 5 (rarely 6) median and 5 lateral chaetae ( Fig. 3 ). With 5–7+5–7 postlabial chaetae along ventral line. Mandibles strong. Capitulum of maxilla with 3 teeth and 6 unmodified lamellae, without long denticles, not projecting beyond tip of capitulum.

Tibiotarsi with 8, 9, 9 acuminate apical chaetae on Leg I–III, respectively: with T1 (on all legs) and T4 (on Leg II and III), without T2 and T3. Claws as common for the genus, inner tooth present, not strong, without outer and with two large lateral teeth. Unguiculus 0.5–0.6 as long as inner edge of claw, with minute inner tooth, sometimes hardly developed or absent ( Fig. 6 ). Base of Leg I with 3 outer chaetae (coxa with 2 and subcoxa with 1 chaeta, Fig. 11 ). Ventral tube with 3–4+3–4 anterior, 8–11+8–11 latero-distal and 6–7 posterior chaetae. Posterior side with 4 chaetae arranged in transversal row and 2–3 in proximal part. Retinaculum with 4+4 teeth and 7–10 chaetae. Ventral chaetae on thorax absent. Ventroapical thickening of manubrium generally bispinose, usually also with 1–2 additional minute teeth on main part (multispinose) ( Fig. 12 ). Anterior side of manubrium with 2+2 spine-like chaetae and 3+3 long in distal row; central group with 4–8 chaetae ( Figs 12, 13 ). Thickness of medial spine-like chaetae variable ( Fig. 12 ). One chaeta of lateral row on manubrium enlarged. Dens tapering, with annulated posterior side, often slightly expanded in area of spines. Anterior side of dens with 23–28 chaetae, with 1–2 minute and 1 long chaetae at apex ( Fig. 8 ). Posterior side normally with 4 chaetae and 8 spines arranged as: 2 basal chaetae (1 of which much longer than others), 2 shorter chaetae in more distal position (inner chaeta in proximal half thickened) and 4 pairs of spines (in the most proximal pair spines weaker and one can be absent). Inner side of dens normally with 3 spine-like chaetae ( Figs 7, 8 , 16, 17 ). Mucro tridentate, teeth subequal, mucronal chaeta absent.

Chaetae cover sparse. Axial chaetotaxy of Abd. I–IV as 2(3), 3(2), 3, 3 (for half of tergite). Macrochaetotaxy as: 2,2/3,3,3,3 in number on Th. II, III /Abd. I–IV ( Fig. 4 ). Macrochaetae long and rather thick, sparsely but distinctly serrated, number of denticles varies, normally 3–7, fewer on two last abdominal segments. On Abd. V 3.7–4.9 as long as Claw of Leg III, and ca. 3 times longer than tergite length. Sensillar chaetotaxy as 5,5/4,4,4,4,6 (s) and 1,1/1,1,1 (ms) ( Fig. 4 ). S-chaetae shorter than common chaetae, differing well from common chaetae. Th. II with 3 middle-sized accp-s and 2 short al-s, Th. III with 3 middle-sized and 1 short accp-s and 1 short al-s. Abd. I–IV each with 3 middle-sized and 1 short accp-s. Abd. V with 2 middle-sized as-s and 2 accp-s in common position, lateral side with 2 short al-s set together in longitudinal line ( Figs 9, 10 ). Accp-s in front of p-row on Th. II and III, in p-row on Abd. I–III, behind p-row on Abd. I. Ms-chaetae well visible, resembling very short lateral s-chaetae, on Abd. I in front position, on Abd. III usually at p-row, together with short lateral accp-s. Formula Formula of s-chaetae on Th.II–Abd.V: 3+2+ms, 3+2+ms/ 3+1+ms, 3+1+ms, 3+1+ms, 3+1, 4+2, considering middle-sized s-chaetae, short s-chaetae and ms-chaetae. Males present, sexual dimorphism in adult males in reproductive stage absent.

Discussion. The new species resembles S. bishopi which is distributed in eastern U.S.A. ( Christiansen & Bellinger 1998). Both species share specific contrast coloration (deeply black corpus, paler head, and yellow-white extremities), the number of spines on the dens, and sparsely ciliated strong macrochaetae. We had an opportunity to study holotype of S. bishopi kept in the collection of Smithsonian National Museum of National History. It was possible to see the chaetotaxy of the extremities ( Figs 14, 15 ) and outer mouth parts. Holotype of S. bishopi (adult male) has 24 and 26 anterior chaetae on the right and left parts of the dens, 5+5 postlabial chaetae, labial palp with 5 proximal (as for the genus), 4 basomedian (vs. 5 in S. bryophila sp. nov.) and 5 basolateral chaetae, Ant. I with 1–2 long thin s-chaetae (vs. 3–7 S. bryophila sp. nov.) and 3 short ones, 8, 8, 8 acuminate apical chaetae on Leg I–III (vs. 8, 9, 9 in S. bryophila sp. nov.). After Christiansen & Bellinger (1998) and our observations, the North American species has only 1+1 short spine-like chaetae in medial area of distal row. The Asiatic species invariably shows 2+2 such chaetae. Christiansen & Bellinger (1998) also mentioned “3+3 distal ventral chaetae” on the manubrium which was not in the holotype, which factually has 4+4 chaetae of which 3+3 long and 1+1 medial short ( Fig. 15 ). The posterior and anterior sides of dens of the two species are similar. The strong geographical gap and the differences mentioned above validates to describe the Asiatic form as a new species. Many essential morphological characters of S. bishopi remain unknown and call for modern examination, as well for S. multispinata , the second representative of the genus in North America. S. bryophila sp. nov. is well distinguished from sympatric S. draconis sp. nov. and S. goryshini by general appearence, sensillar chaetotaxy, macrochaetae, spines on dens, PAO, axial chaetae, and number of ocelli.

Under low magnification the new species can be easily recognized by contrast coloration (black trunk vs. yellow-white legs) and the huge macrochaetae.

Distribution and ecology. The species is distributed widely in eastern Asia (Fig. 40). It occurs from lowlands to alpine belt and prefers mosses on rotten wood, stones and lower part of tree trunks but is also recorded in forest litter.

Etymology. It is named after its ecological preference to moss.

Figures

FIGURES 3–8. Semicerura bryophila sp. nov.: 3, labial palp (guards not shown); 4, macro- and s-chaetae on body; 5, ocelli and PAO; 6, apical part of tibiotarsus and claw III; 7–8, posterior (7) and anterior (8) sides of dens; Is-nae—two chaetae indicating the subfamily Isotominae, ms—ms-chaeta, ss—small s-chaeta, Semic.—two chaetae indicating the genus Semicerura.

FIGURES 9–15. Semicerura bryophila sp. nov. (9–13) and holotype of S. bishopi (14–15): 9, Abd. III–VI; 10, Abd. IV–V (dorsal area); 11, basal part of Leg I; 12, anterior side of manubrium, central group of chaetae and spine-like chaetae marked; 13, chaetae of central group, another specimen; 14, posterior side of proximal part of dens; 15, anterior side of manubrium. ms—ms-chaeta, s—s-chaeta of middle size, ss—small s-chaeta.

FIGURES 16–19. Outer (16, 18) and inner (17, 19) views of dens in Semicerura bryophila sp. nov. (16, 17) and S. draconis sp. nov. (18, 19). So, Spo, Spi, Si—spines of outer, posterior-outer, posterior-inner, and inner rows.