Match Montana Lichen Taxon Codes to References and Interpret Observation Charts

Each Montana Field Guide species account and its "Obs. by Month" chart share one element code, such as NLT0009720. To match a chart to the right species, compare that code with the scientific name and any synonyms in the species account, then add up the monthly bars and compare the result with the chart total. The nine lichen charts below all resolve to a single species, and every chart's monthly values add up to its own displayed total. The charts count database records by month. They do not show when a lichen is most abundant, the best month to look for it, or whether it grows at a particular place such as Medicine Lake.

The nine codes and the species they belong to

The common names come from the chart titles, which is often how people first find these pages. The element code is the reliable link between the chart and the account. If a common name looks unfamiliar, use the code and the scientific name rather than the common name.

Chart common name	Element code	Scientific name	Synonym listed in account
Earthy Button Lichen	NLT0032210	Tetramelas terricolus	Buellia terricola
Hidden Dot Lichen	NLT0042690	Bacidina contecta	none listed
Alpine Finger Lichen	NLT0009720	Allocetraria madreporiformis	Dactylina madreporiformis
Light Stubble Lichen	NLT0007860	Chaenotheca laevigata	none listed
Silver Patch Lichen	NLT0028200	Sporastatia polyspora	none listed
Varying Rim Lichen	NLT0013230	Lecanora argopholis	none listed
Obscure Cobblestone Lichen	NLT0000820	Acarospora obnubila	none listed
Breuss's Speck Lichen	NLVER04070	Verrucaria breussii	none listed
Membranous Pelt Lichen	NLTEST5140	Peltigera membranacea	none listed

Synonyms matter when you search older literature. A paper on Buellia terricola or Dactylina madreporiformis may describe the same organism that the current account files under Tetramelas terricolus or Allocetraria madreporiformis.

Monthly values, checked

Months not listed in the table below show zero on the chart. The "Account total" column is filled in only where the species account reports its own observation count.

Code	Species	Months with records	Sum of months	Chart total	Account total
NLT0032210	Tetramelas terricolus	May 1, Sep 1, Nov 1	3	3	not shown
NLT0042690	Bacidina contecta	Aug 1	1	1	not shown
NLT0009720	Allocetraria madreporiformis	Jun 2, Jul 9, Aug 6, Sep 1	18	18	19
NLT0007860	Chaenotheca laevigata	Aug 1	1	1	not shown
NLT0028200	Sporastatia polyspora	Jul 3, Aug 3	6	6	not shown
NLT0013230	Lecanora argopholis	Mar 1, Apr 1, May 1, Jun 3, Jul 23, Aug 12, Sep 3, Oct 1, Nov 3	48	48	not shown
NLT0000820	Acarospora obnubila	Sep 1	1	1	not shown
NLVER04070	Verrucaria breussii	Apr 1	1	1	not shown
NLTEST5140	Peltigera membranacea	Apr 1, May 4, Jun 10, Jul 9, Aug 12, Sep 4	40	40	41

Four of the nine charts rest on a single record: Bacidina contecta, Chaenotheca laevigata, Acarospora obnubila and Verrucaria breussii. For these species the chart records one dated observation and nothing about seasonal pattern.

When the chart total and the account total differ

Two species show different numbers on the chart and in the account. Allocetraria madreporiformis has 18 records on the chart (2 + 9 + 6 + 1) and 19 in the account. Peltigera membranacea has 40 on the chart (1 + 4 + 10 + 9 + 12 + 4) and 41 in the account. The time charts leave out records that span more than one month or year, so the chart and the account are not required to match. The pages do not say which record accounts for either gap. Write down both numbers with their sources and the date you viewed them, and don't change one to agree with the other.

How to audit an observation chart

Copy the element code from the chart and confirm that the species account uses the same code.
Record the scientific name, any synonyms, and the source of the name used in the account.
Copy each month's value, including the zeros.
Add the months and compare the sum with the chart total.
Record the account's observation total separately if it has one.
Note the chart's exclusion rule: records spanning multiple months or years are not charted.
Record the date you viewed each page, because both the chart and the account can change as new records are added.

What a monthly count can and cannot support

The Montana Natural Heritage Program database combines records from research and monitoring projects with incidental submissions. A record is accepted when it has a credible identification, a date, an observer and a location with stated spatial precision. Nothing requires the same search effort in every month. A tall July bar can mean more lichen fieldwork took place in July. It does not show that the species is easier to find or more common then.

For example, Lecanora argopholis has 23 of its 48 charted records in July and 12 in August. That supports the statement that most of the database's dated records for this species fall in midsummer. It does not support the statement that July is the best month to see it, that the population peaks in summer, or that it occurs in northeastern Montana prairie. The same reasoning applies to the single August record for Chaenotheca laevigata, which documents one dated observation and nothing more.

The Field Guide's maps follow the same logic. Relative-density maps sort areas by the number of observations submitted. Recency maps sort areas by the age of the newest report. Neither type of map measures seasonal abundance. Neither the maps nor the monthly charts can tell you whether a lichen grows at Medicine Lake or in any specific grassland or wetland. That question needs location records for the site itself.

Following the references in each account

Several accounts include bibliography entries. The Tetramelas terricolus account cites McCune and colleagues, Montana Lichens: An Annotated List (2014), which is a statewide checklist. The Lecanora argopholis account lists Salix (2004), a study of lichens at Lewis and Clark Caverns, and Schubloom (1995), a study of southwestern Montana lichens. The Peltigera membranacea account also lists Schubloom (1995), but the account itself contains no descriptive text. A listed reference tells you where to read next. It does not show that the reference covers your area or supports any particular statement in the account. For Medicine Lake, note that the two regional studies come from southwestern Montana.

A reusable worksheet

Element code:
Scientific name:
Synonyms:
Name authority / source:
Bibliography listed in account:
Geographic scope of each reference:
Chart viewed (date):
Years covered (if documented):
Jan  Feb  Mar  Apr  May  Jun  Jul  Aug  Sep  Oct  Nov  Dec
Sum of months:
Chart total:
Account total:
Exclusions noted:
Effort information available:
Supported interpretation:

Filled in for Allocetraria madreporiformis, the monthly row reads 0 0 0 0 0 2 9 6 1 0 0 0. The sum is 18, the chart total is 18, and the account total is 19. Under exclusions, note that records spanning multiple months are not charted. Under effort, enter none documented. Under supported interpretation, write that the charted records fall between June and September.