Five new species of Minettia (Minettiella) (Diptera, Lauxaniidae) from China

Abstract Five species of Minettia Robineau-Desvoidy, 1830 from the South of China are described as new to science: Minettia (Minettiella) bawanglingensis sp. n., Minettia (Minettiella) clavata sp. n., Minettia (Minettiella) plurifurcata sp. n., Minettia (Minettiella) spinosa sp. n. and Minettia (Minettiella) tianmushanensis sp. n. Minettiella elbergi Shatalkin, 1996 and Minettia japonica Sasakawa, 1995 are treated as junior synonyms of Minettia (Minettiella) dolabriforma (Sasakawa & Kozánek, 1995). A key to five subgenera of Minettia and eleven species of Minettia (Minettiella) is presented.

Actually, all species have pruinosity on the mesonotum and abdomen (only the frons is shining black), so the so-called "glossy" black habitus is not correct. Shatalkin (1996) had elevated the subgenus Minettiella to the genus level when he described Minettiella elbergi Shatalkin, 1996. Shatalkin (2000 discussed that its having genus rank was based on the specialized male genitalia and the above-mentioned diagnosis, and noted that the described species Minettiella acrostichalis (Sasakawa & Kozánek, 1995) was possibly a synonym of Minettiella coracina , and two described species Minettiella elbergi and Minettia japonica  were possibly synonyms of Minettiella dolabriforma (Sasakawa & Kozánek, 1995) (Shatalkin 2000). We examined the male genitalia of some specimens from five subgenera of Minettia and found that the diversity of the male genitalia (that is, there are lots of many different forms among the species) exists in the three subgenera Minettia, Minettiella and Plesiominettia Shatalkin, 2000, which is more diversity of male genitalia than that in two subgenera Frendelia (Collin, 1948) and Scotominettia (Shatalkin, 2008) based on many examined specimens of five genera from the Palaearctic and Oriental regions. The diversity of the male genitalia in Minettiella is the same as that in Minettia and (Sasakawa & Kozánek, 1995), so the species M. (Minettiella) coracina Shatalkin is considered to be a valid species.
The type specimen of M. (Minettiella) atrata (Meijere, 1910) was recorded in Jong (2000) as missing the male genitalia, but fortunately the description and diagnosis is adequate to separate it from other species.
In total, there are eleven known species of the subgenus Minettiella with six currently found in China (see Appendix for species checklist).

Materials and methods
The general terminology follows Gaimari and Silva (2010). Genitalia preparations were made by removing and macerating the apical portion of the abdomen in cold saturated NaOH for 6 hours. After examination, they were transferred to glycerine for examination and stored in a microvial on the pin below the specimen. Specimens examined were deposited in China Agricultural University, Beijing, China (CAUC).

Species descriptions
Unless otherwise specified, the following seven species described below are characterized as follows: Head, thorax and abdomen black. Frons wider than long and parallel-sided. Face and parafacial flat with dense whitish gray pruinosity. Ocellar triangle black; oc developed, shorter than anterior or, anterior or reclinate, shorter than posterior or. Arista black with yellow at base. Scutellum black, with brown grayish pruinosity. All femora black or blackish brown. Wing slightly yellow, hyaline. Halter yellow.
Head. Frons slightly concave with narrow yellow anterior margin. Gena about 1/4 eye height. Antenna scape and pedicel yellowish brown to brown, 1st flagellomere blackish brown with yellow at base and nearly 2.3 times longer than high; arista bare. Proboscis black with dark yellow at apex. Palpus black.
Thorax with brownish gray pruinosity. Mesonotum with 1+3 dc, acr in 2 rows with 1+3 long acr in front of prsc and one pair of prsc as long as 1st postsutural dc. Legs: fore tibia mostly yellowish brown with yellow at base and black at apex; mid tibia yellow and hind tibia yellow with brown at apex; fore tarsi with basitarsus yellow on basal 3/4 and tarsomeres 2-5 brown, mid and hind tarsi with tarsomeres 1-2 dark yellow and tarsomeres 3-5 pale brown. Fore femur with 4 pv and 6 pd, fore tibia with 1 long preapical ad and 1 short apv. Mid femur with 4 a and 1 app; mid tibia with 1 strong preapical ad and 1 strong apv. Hind femura with 1 preapical ad, and hind tibia with 1 weak preapical ad and 1 short apv. Wing with costa with 2nd (between R 1 and R 2+3 ), 3rd (between R 2+3 and R 4+5 ) and 4th (between R 4+5 and M 1 ) sections in proportion of 6.7:1:1, r-m at middle of discal cell; ultimate and penultimate sections of M 1 in proportion of 1:1.1; ultimate section of CuA 1 about 1/6 of penultimate section.
Abdomen with sparse brownish gray pruinosity. Male genitalia : syntergosternite semicircular with three pairs of dorsal setulae, epandrium narrow basally and broad apically, with a deep concave on anterior ventral margin and a digitiform anterior process, triangular apically in lateral view; surstylus separated from epandrium, elliptical in lateral view but crescent-shaped in posterior view; hypandrium nearly Y-shaped; postgonite forming a complete sclerite, with a median ridge; aedeagus consisting of a pair of clavate inner sclerites with short setulae and a pair of dorsolateral concaves, rounded apically; height of aedeagal apodeme nearly as long as aedeagus and broad in ventral view. Female terminalia (Figs  Head. Frons slightly concaved with yellow anterior margin. Gena about 1/6 eye height. Antenna blackish brown, 1st flagellomere yellow at base, and 1st flagellomere nearly 1.6 times longer than high; arista pubescent, with longest rays about 1/4 height of 1st flagellomere. Proboscis black with dark yellow at apex and palpus black. Thorax with brownish gray pruinosity. Mesonotum 0+2 dc (anterior dc far behind transverse scutal suture), acr in 6 rows; two pairs of long acr present in front of prsc, prsc slightly shorter than 1st post-sutural dc. Legs: tibia black with yellow at base, mid and hind tarsi yellow. Fore femur with 4 pv and 8 pd, fore tibia with 1 short preapical ad and 1 short apv. Mid femur with 3 a and 1 app; mid tibia with 1 strong preapical ad and 1 strong apv. Hind femura with 1 weak preapical ad, hind tibia with 1 weak preapical ad and 1 short apv. Wing with costa with 2nd (between R 1 and R 2+3 ), 3rd (between R 2+3 and R 4+5 ) and 4th (between R 4+5 and M 1 ) sections in proportion of 7:1.3:1; r-m beyond middle of discal cell; ultimate and penultimate Abdomen with sparse brownish gray pruinosity. Male genitalia (Figs 6-10): syntergosternite circular with a weak ventral bridge, epandrium with a tiny subapical concave, surstylus separated from epandrium, consisting of a long claviform process with setulae in lateral view and with a long triangular process in posterior view; hypandrium slender, projecting medially and nearly V-shaped; postgonite contorting, consisting of an acute triangular apical process and three apical setae; aedeagus columnar, truncate basally and blunt rounded apically, consisting of a triangular dorsal process subapically in lateral view and a black bottle-shaped inner process with an elliptical incision and many spiculate processes in ventral view; aedeagal apodeme narrow and short, projecting forwards, nearly right angle between hypandrium and aedeagus. Female terminalia (Figs 33-34): sternite 7 trapeziform with long setae on posterior margin, sternite 8 semicircular with three pairs of long setae on posterior margin and sternite 9 with a groove; spermathecae 2+1, round and all stems leading to the three spermathecae narrow apically.
Remarks. The new species is very similar to M. (Minettiella) dolabriforma from the Palaearctic region in the following characteristics: mesonotum 0+2 dc, legs black with base of tibia yellow and mid and hind tarsi yellow, but it can be separated from the latter in the following characteristics: surstylus consisting of a long claviform process with setulae in lateral view and with a long triangular process in posterior view; hypandrium projecting medially and nearly V-shaped; aedeagus consisting of a triangular dorsal process subapically in lateral view and a black, bottle-shaped inner process with an elliptical incision and many speculate processes in ventral view. In M. (Minettiella) dolabriforma, the surstylus has a spatulate process, narrow ventrally and pointed at apex in lateral view; the hypandrium is U-shaped; the aedeagus is pointed dorsoapically with a lobate dorsal process in lateral view, and is spinulose and brownish-striated on the median ventral membrane in ventral view . The new species is also similar to M. (Minettiella) atrata from Indonesia (Java) in mesonotum with 0+2 dc and a pair of long acr present in front of prsc, but it can be separated from the latter in the arista having microscopic setulae, and the mid and hind tarsi being yellow. In M. (Minettiella) atrata, the arista is short plumose and only the hind tarsi are yellow (Meijere 1910 Diagnosis. Antenna yellow with 1st flagellomere brown on apical 2/3; arista plumose, with longest rays slightly shorter than height of 1st flagellomere. Mesonotum 0+3 dc, anterior dc weak, hair-like; acr in 6 rows. All tibiae black with pale yellow at base; fore tarsi black, mid and hind tarsi dark yellow. Mid femur with 5 a.
Head. Face slightly shining. Frons with yellow anterior margin. Gena about 1/6 eye height. Antenna yellow with brown on apical 2/3 of 1st flagellomere, 1st flagellomere nearly 1.7 times longer than high; arista plumose, with longest rays slightly shorter than height of 1st flagellomere. A blackish brown rectangular spot present between eye and base of antenna. Proboscis and palpus black.
Thorax with brownish gray pruinosity. Mesonotum 0+3 dc (anterior dc weak, hair-like, far behind transverse scutal suture), acr in 6 rows; prsc longer than 1st post-sutural dc; anepisternum with setulae on lower margin. Legs: all tibiae black with pale yellow at base; fore tarsi black, mid and hind tarsi dark yellow. Fore femur with 4 pv and 6 pd, fore tibia with 1 short preapical ad and 1 short apv. Mid femur with 5 a and 1 app; mid tibia with 1 strong preapical ad and 1 strong apv. Hind tibia with 1 weak preapical ad and 1 short apv. Wing with costa with 2nd (between R 1 and R 2+3 ), 3rd (between R 2+3 and R 4+5 ) and 4th (between R 4+5 and M 1 ) sections in proportion of 4:1.7:1; r-m at middle of discal cell; ultimate and penultimate sections of M 1 in proportion of 1:1.1; ultimate section of CuA 1 about 1/5 of penultimate section.
Remarks. The new species is very similar to M. (Minettiella) plurifurcata sp. n. (see discussion under M. (Minettiella) plurifurcata sp. n.) from China (Hubei). This new species is also similar to M. (Minettiella) atrata from Indonesia (Java) in having the arista short plumose and the mesonotum with acr 6 rows, and without other strong acr in front of strong prsc, but it can be separated from the latter by the mid and hind tarsi being yellow. In M. (Minettiella) atrata, only the hind tarsi are yellow (Meijere 1910;Malloch 1929 Etymology. Latin, pluri-, meaning many, and furcata, meaning forked; referring to the aedeagus with forked and acute processes in different lengths; a feminine adjective. Diagnosis. Arista plumose, with longest rays slightly shorter than height of 1st flagellomere. Thorax with whitish gray pruinosity, sparse on anterior 1/2 and dense on posterior 1/2. Mesonotum 0+3 dc (anterior dc far behind transverse scutal suture), acr in 6 rows. All tibiae pale yellow at base; fore tarsi black, mid and hind tarsi dark yellow. Mid femur with 4 a.
Description. MALE. Body length 3.7 mm, wing legth 4.2 mm. Head. Frons with yellow anterior margin. Gena about 1/7 eye height. Antenna yellow with brown on apical 2/3 of 1st flagellomere, 1st flagellomere nearly 2.0 times longer than high; arista plumose, with longest rays slightly shorter than height of 1st flagellomere. A black round spot present between eye and base of antenna. Proboscis and palpus black.
Thorax with whitish gray pruinosity, sparse on anterior 1/2 and dense on posterior 1/2. Mesonotum 0+3 dc (anterior dc far behind transverse scutal suture), acr in 6 rows; prsc as long as 1st postsutural dc; anepisternum with setulae on lower margin. Legs: tibia black with pale yellow at base; fore tarsi black, mid and hind tarsi dark yellow. Fore femur with 5 pv and 8 pd, fore tibia with 1 short preapical ad and 1 short apv. Mid femur with 4 a and 1 app; mid tibia with 1 strong preapical ad and 1 strong apv. Hind tibia with 1 weak preapical ad and 1 short apv. Wing with costa with 2nd (between R 1 and R 2+3 ), 3rd (between R 2+3 and R 4+5 ) and 4th (between R 4+5 and M 1 ) sections in proportion of 5.2:4:1; r-m at middle of discal cell; ultimate and penultimate sections of M 1 in proportion of 1:1.2; ultimate section of CuA 1 about 1/5 of penultimate section.
Abdomen with sparse whitish gray pruinosity. Male genitalia : syntergosternite circular with dorsal setulae, epandrium with a wide median incision on dorsal margin in lateral view; surstylus short subuliform and originating from inner side of epandrium in lateral view and convergent apically in posterior view; hypandrium nearly W-shaped; postgonite slender, slightly curved with 2-3 short apical setulae; aedeagus slender, columnar and rounded apically, with furcated acute processes in different length; aedeagal apodeme short, as long as 1/3 length of aedeagus.
FEMALE. Unknown. Remarks. The new species is very similar to M. (Minettiella) clavata sp. n. from China (Hubei) in the following characteristics: acr in 6 rows; all femora black and tibiae black with pale yellow at base; fore tarsi black, mid and hind tarsi dark yellow; wing yellow at base, but it can be separated from the latter in the following characteristics: the mesonotum having whitish gray pruinosity, sparse on anterior half and dense on posterior half, and 0+3 dc, anterior dc strong; the surstylus being long triangular and originating from the inner side of the epandrium. In M. (Minettiella) clavata, the mesonotum has 0+3 dc with anterior dc weak, hair-like; the epandrium is nearly rectangular; the surstylus is fused with the epandrium, and claviform with a triangular basal process a projecting apical process, a small acute ventroapical process and a tiny incision in lateral view.
Distribution. China (Hubei). Diagnosis. Body black with brownish gray. Face and parafacial black flat with dense whitish gray pruinosity. Antennal 1st flagellomere blackish brown except yellow at base. Mesonotum 0+2 dc (anterior dc far behind transverse scutal suture), acr in 4 rows; a pair of long acr present in front of prsc. Legs mostly black except fore basal tarsus dark yellow on basal 3/4 and mid and hind tarsi dark yellow. Basal part of wing yellow. Abdomen shining black with sparse brownish gray pruinosity.
Head black. Frons shining black except yellow, slightly concaved anterior margin; oc slightly longer than anterior or. Gena about 1/6 height of eye. Antenna scape and pedicel yellowish brown, 1st flagellomere blackish brown except yellow on basal part, 1st flagellomere nearly 1.8 times longer than high; arista with microscopic setulae. Proboscis black except yellow at apex; palpus black.
Thorax black with brownish gray pruinosity. Mesonotum with 0+2 dc (anterior dc far behind transverse scutal suture), acr in 4 rows; a pair of long acr present in front of prsc, prsc nearly as long as 1st postsutural dc; 1 ia, 1 kepst. Legs with fore basal tarsus dark yellow on basal 3/4 and mid and hind tarsi dark yellow. Fore femur with 5 pv, 8 pd, fore tibia with 1 long preapical ad and 1 short apv. Mid femur with 4 a and 1 app; mid tibia with 1 strong preapical ad, 1 strong apv. Hind femura with 1 weak preapical ad, hind tibia with 1 weak preapical ad and 1 short apv. Wing: costa with 2nd (between R 1 and R 2+3 ), 3rd (between R 2+3 and R 4+5 ) and 4th (between R 4+5 and M 1 ) sections in proportion of 6:1.7:1; r-m at middle of discal cell; ultimate and penultimate sections of M 1 in proportion of 1:1.1; ultimate section of CuA 1 about 1/6 of penultimate section.
Abdomen black with sparse brownish gray pruinosity. Male genitalia: protandrium semicircular (with a weak ventral bridge in a few specimens), narrow under spiracle; epandrium slender, with dorsal setae in lateral view; surstylus separated from epandrium, slender, narrow apically with a falcate apical process in lateral view; hypandrium very narrow at middle and broad on two lateral sides; postgonite columnar with two long setae; aedeagus acute apically with a tiny incision in ventral view but oblique truncate apically in lateral view; aedeagal apodeme nearly as long as aedeagus. Female terminalia: tergite 6 with a pair of long dorsal setae on posterior margin; spermathecae 2+1, round.
Remarks. The species is very similar to Minettia (Minettiella) tianmushanensis sp. n. from Zhejiang (see M. (Minettiella) tianmushanensis sp. n.). The new species is also similar to Minettia (Minettiella) atrata from Indonesia (Java) in the following characters: mesonotum with 0+2 dc and a pair of long acr present in front of prsc, but it can be separated from the latter by the arista having microscopic setulae, the mesonotum having the acr in 4 rows, and the legs mostly black except the fore basal tarsus dark yellow on basal 3/4 and the mid and hind tarsi dark yellow. In Minettia (Minettiella) atrata, the arista is short plumose, the mesonotum has acr in 6 rows and the hind tarsi is yellow (Meijere 1910). Etymology. Latin, spinosa, meaning spinose or with spinules; referring to the aedeagus with many short ventral spinules; a feminine adjective.

Minettia
Diagnosis. Face with a yellow triangular median spot or only slightly yellow in center of face. Arista with microscopic setulae, longest rays shorter than 1/3 height of 1st flagellomere. All tibiae dark yellow and tarsi dark yellow with tarsomeres 3-5 pale brown (apex of fore tibia pale brown in a few specimens); mid femur with 3 a. Wing black at base. Head. Face with a yellow triangular median spot or only slightly yellow in center of face, and parafacial brown with dense whitish gray pruinosity. Frons with yellow anterior margin (sometimes with a wide yellow median stripe in a few of specimens). Gena about 1/6 eye height. Antenna yellow with pale brown on apical 2/3 of 1st flagellomere, 1st flagellomere nearly 1.7 times longer than high; arista with microscopic setulae, longest rays shorter than 1/3 height of 1st flagellomere. An indistinct brown spot present between eye and base of antenna. Proboscis black with dark yellow at apex and palpus black.
Thorax with sparse whitish gray pruinosity. Mesonotum 0+3 dc (anterior dc far behind transverse scutal suture), acr in 6 rows; prsc slightly longer than 1st postsutural dc. Scutellum with dense yellowish brown pruinosity. Legs: all tibiae dark yellow and tarsi dark yellow with tarsomeres 3-5 pale brown (apex of fore tibia pale brown in a few specimens). Fore femur with 5 pv and 8 pd, fore tibia with 1 short preapical ad and 1 short apv. Mid femur with 3 a and 1 app; mid tibia with 1 strong preapical ad and 1 strong apv. Hind femura with 1 weak preapical ad, hind tibia with 1 weak preapical ad and 1 short apv. Wing slightly yellow with black at base; costa with 2nd (between R 1 and R 2+3 ), 3rd (between R 2+3 and R 4+5 ) and 4th (between R 4+5 and M 1 ) sections in proportion of 11:1.5:1; r-m at middle of discal cell; ultimate and penultimate sections of M 1 in proportion of 1:1.2; ultimate section of CuA 1 about 1/6 of penultimate section.
Abdomen with sparse whitish gray pruinosity. Male genitalia (Figs 21-25): syntergosternite circular with a setula near spiracle, epandrium with a small subapical incision in lateral view and acute apically in posterior view, and surstylus contorting with apical setulae and originating from inner side of epandrium in lateral view; hypandrium slender, nearly H-shaped and hypandrial apodeme indistinct; pregonite tiny, slightly curved with two setulae; aedeagus broad, with dorsal sclerite round apically, membranous parts beyond apex of dorsal sclerite with short spinules and a pair of long hook-like basal processes; aedeagal apodeme slender. Female terminalia (Figs 39-40): sternite 7 rectangular, slightly concave on prosterior margin, sternite 8 semicircular with a pair of processes on anterior margin and a wide groove between processes; spermathecae 2+1, round.
Remarks. The new species is similar to M. (Minettiella) plurifurcata sp. n. from Hubei in the following characteristics: mesonotum 0+3 dc, acr in 6 rows; fore femur with 5 pv and 8 pd, but it can be separated from the latter in the epandrium having a small subapical incision in lateral view and acute apically in posterior view and the surstylus being contorting with apical setulae in lateral view. In M. (Minettiella) plurifurcata, the epandrium has a wide median incision on the dorsal margin in lateral view and the surstylus is short subuliform in lateral view and convergent apically in posterior view.
Distribution. China (Hubei). Etymology. The new species is named after the type locality Tianmushan National Nature Reserve, Zhejiang Province Diagnosis. Frons slightly upturned with yellow anterior margin and short brownish yellow median stripe. Antenna brown with 1st flagellomere yellow at base; arista pubescent, with longest rays about 1/3 height of 1st flagellomere. Mesonotum 0+2 dc, acr in irregular 4 rows. Mid tarsi dark yellow and basitarsus with 1 subbasal pv, and hind tarsi dark yellow.
Head. Frons with yellow anterior margin, slightly upturned and short brownish yellow median stripe. Gena about 1/10 eye height. Antenna brown with 1st flagellomere yellow at base and 1st flagellomere nearly 1.8 times longer than high; arista pubescent, longest rays about 1/3 height of 1st flagellomere. Proboscis and palpus blackish brown.
Thorax with brownish gray pruinosity. Mesonotum with 0+2 dc, acr in irregular 4 rows, a pair of long acr in front of prsc, prsc longer than 1st postsutural dc. Legs: tibia black, fore tarsi black, mid and hind tarsi dark yellow. Fore femur with 4-5 pv and 8 pd, fore tibia with 1 long preapical ad and 1 short apv. Mid femur with 3-4 a and 1 app; mid tibia with 1 strong preapical ad and 1 strong apv, mid basitarsus with 1 subbasal pv. Hind femur with 1 preapical ad, hind tibia with 1 weak preapical ad and 1 short apv. Wing with costa with 2nd (between R 1 and R 2+3 ), 3rd (between R 2+3 and R 4+5 ) and 4th (between R 4+5 and M 1 ) sections in proportion of 5:1:1; r-m beyond middle of discal cell; ultimate and penultimate sections of M 1 in proportion of 1:1.1; ultimate section of CuA 1 about 1/6 of penultimate section.
Abdomen with sparse brownish gray pruinosity. Male genitalia (Figs 26-30): syntergosternite circular; epandrium slender, nearly rhombic and narrow apically; surstylus separated from epandrium, contorted claviform in lateral view and subuliform in posterior view with two acute apical teeth; hypandrium nearly U-shaped in ventral view, hypandrial apodeme distinct; postgonite S-shaped with two apical setulae in lateral view; aedeagus subuliform, narrow apically with a small incision in ventral view and wide rectangular, slightly projecting subapically with a small acute apical process in lateral view; aedeagal apodeme long, as long as height of aedeagus. Female terminalia (Figs 41-43): ternite 7 concave in lateral view, tergite 8 constricted medially; sternite 9 semicircular, sternite 8 slender, sternite 7 concave apically with a pair of triangular apical processes, curved outward; spermathecae 2+1, elliptical. Remarks. The new species is very similar to M. (Minettiella) sasakawai from China (Hainan) and Vietnam in the following characteristics: mesonotum with 0+2 dc, acr in 4 rows, and a pair of long acr present in front of prsc; wing pale yellow at base, but it can be separated from the latter in the syntergosternite being circular, the surstylus being contorting and claviform in lateral view and subuliform in posterior view with two acute apical teeth, and the female abdominal tergite 6 having no long dorsal setae on the posterior margin. In M. (Minettiella) sasakawai, the syntergosternite is semicircular and narrow under the spiracle; the surstylus is slender, narrow apically with a falcate apical process in lateral view and the female abdominal tergite 6 has a pair of long dorsal setae on the posterior margin.
Distribution. China (Zhejiang). Basal part of wing black; arista long plumose, with longest rays longer than height of 1st flagellomere (rarely shorter than height of 1st flagellomere); male genitalia: ventral hypandrial appendages represented by two pairs of sclerites (including some Palaearctic and Oriental species Mesonotum with brownish grey pruinosity, 1st postsutural dc weak, hairlike, prsc longer than 1st postsutural dc; male genitalia: surstylus fused with the epandrium, claviform with a triangular basal process, a projecting apical process, a small acute ventroapical process and a tiny incision in lateral view (Figs 11, 13)  Face with a yellow triangular median spot or only slightly yellow at middle of face, and parafacial with dense whitish gray pruinosity; arista with microscopic setulae, longest rays shorter than 1/3 height of 1st flagellomere; mid femur with 3 a; male genitalia: epandrium with a small subapical incision in lateral view and acute apically in posterior view, surstylus contorted with apical setulae and originating from inner side of epandrium in lateral view (Figs 21,23); female sternite 8 semicircular with a pair of processes on anterior margin and a wide groove between processes (Fig 39)